Impressions of the 1956 Stockholm congress of the international society of photogrammetry

PHOTOGRAMMETRIA

Nr. 1

Impressions of the 1956 Stockholm Congress of the International Society of Photogrammetry by W. S C H E R M E R H O R N , Delft, Holland.

1. Introduction. A l t h o u g h it is a t e m p t a t i o n to me to compare m y f i r s t i n t e r n a t i o n a l conference on p h o t o g r a m m e t r y , now exactly 30 y e a r s ago, w i t h the situation in p h o t o g r a m m e t r y as shown on the I n t e r n a t i o n a l C o n g r e s s in Stockholm, I will not r e p e a t the historical review I gave in m y article about the i m p r e s s i o n s of the 1952 W a s h i n g t o n Congress in t h i s review [1]. One of the g r e a t e s t d i f f e r e n c e s is w i t h o u t a n y doubt t h a t the Stockholm confe.rence was really i n t e r n a t i o n a l : 41 countries were represented either as a m e m b e r c o u n t r y or by guests. This proves t h a t p h o t o g r a m m e t r y n o w a d a y s is accepted a n d recognized all over the world as a n o r m a l s u r v e y technique. It m a y be t h a t m a n y of these countries only contributed to t h e conference by their presence and by the participation of their r e p r e s e n t a t i v e s in personal discussions, b u t this is due to t h e r a t h e r recent estab l i s h m e n t of p h o t o g r a m m e t r i c services in several of these countries. We t h e r e f o r e expect t h a t on the n e x t Congress m a n y of these countries will participate not only in a passive way, b u t also more actively by p r e s e n t i n g national i~eports c o n t r i b u t i n g to Commission reports a n d by papers. This will h a v e consequences for the organization of the n e x t cong r e s s as I will explain in the l a s t p a r a g r a p h .

2. Organization and character of the Stockholm Congress. Our Swedish colleagues h a v e done their u t m o s t to organize the Congress in such a w a y t h a t a s a t i s f a c t o r y discussion and exchange of views could t a k e place. Their aim h a s been to publish p a p e r s in advance and to m a k e the r e p o r t s of the commissions available to all p a r t i c i p a n t s before the congress. In order to reach t h i s aim the Swedish B u r e a u of the I n t e r n a t i o n a l Society announced a strict time table for all technical communications and required s u m m a r i e s of all p a p e r s before the 1st of March 1956. These summ a r i e s reached several of us, in p a r t i c u l a r in the E u r o p e a n countries, in time to be studied before the Congress. F r o m t h i s point of view the Swedish organization w a s an i m p o r t a n t i m p r o v e m e n t compared w i t h previous congresses. E a c h p a r t i c i p a n t of the C o n g r e s s could now obtain some impression about the subject of t h e p a p e r s and sometimes p r e p a r e h i m s e l f in the few weeks or d a y s left before his d e p a r t u r e for Stockholm. We, in the ITC, for instance h a v e been m o s t g r a t e f u l to our Swedish f r i e n d s for this, because bl this w a y we were able to organize a p r e p a r a t o r y discussion of congress subjects in a one week's s u m m e r course j u s t before the conference. The set-up r e g a r d i n g the detailed m a t e r i a l provided to the congress in the f o r m of r e p r i n t s of articles w a s less succesful. These r e p r i n t s were required three m o n t h s in advance, b u t could not be distributed a m o n g s t the p a r t i c i p a n t s before the Congress. T h i s was done d u r i n g the Congress and each of the p a r t i c i p a n t s h a d to f o r w a r d by special marl a h e a v y load of p a p e r f r o m Stockholm to his home c o u n t r y w i t h o u t h a v i n g the chance for a p r o p e r ' s t u d y of these papers. A f u r t h e r consequence of t h i s c h a n g e in organization w a s the alteration in the publication of the I n t e r n a t i o n a l Archives for which the Swedish Congress B u r e a u as such h a s taken the initiative ~ d t h e responsibility. The intention w a s to organize the publicat:on of t h e A r c h i v e s in such a w a y t h a t a two y e a r s ' delay could be avoided. It is t r u e t h a t this delay w a s a g r e a t d i s a d v a n t a g e of the method applied in the past. Therefo e the, C o n g r e s s B u r e a u decided to d i s t r i b u t e a t the Congress volume II and III containing the 1,

2 national reports and the reports of the seven technical commissions. F u r t h e r m o r e we received in a stiff cover all loose reprints which f o r m P a r t IV of the Archives. This cover however cannot be used by libraries or institutions and by many private persons and they are obliged to order a more costly binding t h a n required for the previous volumes. Still greater is the disadvantage t h a t in the p a r t containing the papers no continuous numbering of the pages will be made. This makes the use more difficult than of previous volumes. In conclusion we find t h a t only the publications of the summaries which will be included with the records of the meetings in p a r t I of vol. XII are a real improvement. This cannot be said of the other changes in the method of publication of the International Archives. We believe t h a t in the future such changes in the method of publication of the Archives can only be allowed a f t e r an authorisation of the general assembly of the ISP. Other characteristics of this Congress were the enormous number of papers, partly read by title and the almost complete lack of a real discussion. Many of the highly specialized subjects, such as for instance problems of adjustment of aerial triangulation, could perhaps have been discussed if, f i r s t of all, more time had been available for explanation of the paper and secondly if the audience had been much smaller and consisting only of those really interested in this particular subject. Now the whole climate of the commission meetings w a s such t h a t discussions could only be very brief and not thoroughly enoug h. This was the c o n t r a r y to the experience we gained in the ITC's second summer course week, which was used for a thorough discussion of the most important subjects of the Congress. There was a possibility for the discussion which should have taken place in many of the commission meetings. The difference, however, was t h a t in this one week's course the number of subjects was limited to the most important items from the Congress in Stockholm. A f u r t h e r characteristic is that for the f i r s t time the Congress of the I S P was attended by guests from behind the iron curtain. There was quite an i m p o r t a n t delegation from Russia and Poland. Although these guests were not announced in advance the Congress Bureau gave the Russian delegation the chance to make a few communications which, however, came not f a r above general remarks; the audience learned nothing t h a t was not already known from recent publications de'dyed directly from Russian sources. In a private conversation, however, one of the leading Russian representatives supposed t h a t p e r h a p s during the next conference in London the Russian delegation would be able to speak not only in general terms, but above all to show instruments and work used in t h a t country. This time the benefit of the participation of the guests was more on the Russian side than on t h a t of the member countries. The organization of the Congress was made very difficult to our Swedish friends by the f a c t t h a t so many members of the Congress did not announce t h e i r p a r t i c i p a t i o n at all or at the last moment. The number of p a r t i c i p a n t s was much larger than expected in advance.

3. Comm. I. Photography. As a general remark it must be stated t h a t in the field of navigation, flight planning and flight operations only few presentations of importance were made. Worse perhaps was the lack of the products of the American industry in this commission. In particular the absence of the new American cameras of Fairchild with Bausch and Lomb Planigon Lens left a gap in the remarkable exhibit of the mainly European firms. The important new features were the Wild-Bertele super wide-angle lens, which combined a large angle of field with an excellent quality of the image (the Super Aviogon). There were as new creations an improved Ross lens and the Zeiss wide-angle Pleogon lens, competitors of the now already famous Wild-Bertele Aviogon, which was present together with the Wild-Bertele Aviotar in cameras RC5, RC7, RC8 and with the well-known Zeiss Topar standard angle lens. There is no doubt t h a t these latest develop-

3 m e n t s in lens design s i g n i f y a g r e a t step f o r w a r d in the general quality of photographic images. The expression of image q u a l i t y by m e a n s of the definition of resolving power, resolution or s h a r p n e s s becomes more a n d more doubtful, n o t w i t h s t a n d i n g the g e n e r a l use of these in p h o t o g r a m m e t r y . The resolution is a v e r y weak description of w h a t h a p p e n s in image f o r m a t i o n a n d in h u m a n vision. We d r a w t h e a t t e n t i o n to the work presented by I n g e l s t a m m on c o n t r a s t t r a n s m i s s i o n a n d c o n t r a s t ]'eduction values in i m a g e f o r m a tion. In this i m p o r t a n t work the modern t r e n d of d e f i n i n g " s h a r p n e s s " in a physicalm a t h e m a t i c a l w a y is demonstrated. P e r h a p s t h a t by f u r t h e r development along this line it will be possible to create n e w m e a n s to e x p r e s s image quality a n d t h u s come to a more objective comparison of the quality of p h o t o g r a m m e t r i c c a m e r a s a s used nowadays. R e g a r d i n g these photographic qualities of i m a g e s we m u s t bear in m i n d t h a t photographic m a t e r i a l s a n d techniques show n o w a d a y s a better resolution with a g r e a t e r speed t h a n those available 10-20 y e a r s ago. A g r a d u a l p r o g r e s s h a s been m a d e since. O u r pers.onal experience in v a r i o u s p a r t s of the world gives us the impression t h a t the difficulties in air p h o t o g r a p h y do n o t arise f r o m lack of good m a t e r i a l , b u t more f r o m a lack of well-trained s t a f f and personnel. In several o r g a n i z a t i o n s a i r p h o t o g r a p h y is not treated as a science, b u t m o r e like a chemical h a n d i c r a f t . T h e r e is a n e n o r m o u s discrepancy between the h i g h scientific s t a n d a r d of the factories of photographic m a t e r i a l s and t h a t of the organizations who u s e these m a t e r i a l s . R e g a r d i n g photographic m a t e r i a l s the question film v e r s u s plate r e m a i n e d unsolved. The n u m b e r of complications increases on both sides. The difficulties with f l a t n e s s of glass plates become more and more known a n d a recent s t u d y in the British P h o t o g r a m metric Record [2] d r a w s the a t t e n t i o n to the influence of the flexion of the plate u n d e r the influence of its own weight. This, however, is a theoretical s t u d y because the tensions of the n e g a t i v e s in their f r a m e s will r e m a i n d i f f e r e n t f r o m those a s s u m e d by this author. There are moreover results, which cause a preference for g l a s s plate n e g a t i v e s and others which show no i m p o r t a n t difference. The Stockholm C o n g r e s s h a s left this problem in entirely the s a m e position a s before. P e r h a p s f r o m the i n v e s t i g a t i o n s u n d e r w a y we m a y expect a clarification of t h i s problem in a not too d i s t a n t f u t u r e . We consider as i m p o r t a n t the n e w electronic s c a n n i n g spot printer. T h i s was shown for the f i r s t time and will enable i m p r o v e m e n t of i m a g e r e p r e s e n t a t i o n in m a n y cases. The creation w a s announced of the U S A Log Etronic and of the Cintel I n s t r u m e n t m a d e by Cinema-Television Ltd., in E n g l a n d . The E n g t i s h prototype w a s shown; of the American i n s t r u m e n t s only the technical d a t a were available, b u t t h e i n s t r u m e n t itself w a s not exhibited. R e g a r d i n g enlargers, rectifiers, reduction p r i n t e r s etc. we h a v e to mention t h e Zei~s SEG ¥ Rectifier and t h e Wild E n l a r g e r VG I. The importance of both i n s t r u m e n t s lies in the f a c t t h a t the lenses used in these reproductio n i n s t r u m e n t s are adapted to the modern s t a n d a r d s of precision a n d image quality of the m o d e r n c a m e r a s of t h e s a m e f i r m s . It h a s no sense to u s e a h i g h q u a l i t y Pleogon or Aviogon lens to spoil a f t e r w a r d s the r e s u l t s in an e n l a r g e r or rectifier which h a s a lens of a m u c h lower quality. W i t h such a combination a mosaic for i n s t a n c e can never be u p to s t a n d a r d n o t w i t h s t a n d i n g the h i g h q u a l i t y of the negatives. The reduction p r i n t e r s , such a s those of Zeiss a n d Wild (which could be better called " t r a n s f o l ' m i n g p r i n t e r s " ) will become m o r e a n d m o r e important. T h e i r f u n c t i o n is not to ]'educe, but to c a r r y out a t r a n s f o r m a t i o n of t h e original p h o t o g r a p h into another, in order to m a k e r e s t i t u t i o n more independent f r o m sizes, principal distances and distersions of the air camera. A d e m a n d m a d e upon t h i s t r a n s f o r m i n g p r i n t e r is t h a t it should fulfill v e r y strict specifications r e g a r d i n g mechanical a n d optical precision. In this section Nistri presented his telescopic p r i n t e r - r e c t i f i e r which is a t r a n s f o r m i n g p r i n t e r , acting a t t h e s a m e time as rectifier. T h i s i n s t r u m e n t m a y be used in such cases where the elements of c a m e r a orientation are obtained with s u f f i c i e n t reliability by m e a n s of

4 a gyroscope o r horizon picture. The production of such diapositives can be i m p o r t a n t if we p r e f e r r e s t i t u t i o n of our p h o t o g r a p h s in a t h i r d - o r d e r a p p r o x i m a t e plotting i n s t r u m e n t (see our discussion of this subject u n d e r Comm. II). R e g a r d i n g the d e t e r m i n a t i o n of c a m e r a orientation at the m o m e n t of exposure there w a s not m u c h news of Spectacular character. "A new method, introduced by P a l m e r and developed in C a n a d a , d e t e r m i n e s the strip b e n d i n g s in a z i m u t h by m e a n s of f o r w a r d oblique i n f r a r e d p h o t o g r a p h y . It is a kind of f o r w a r d alignmen~ in successive obliques. (See our discussion about commission III.) Other methods such a s Shoran, H i r a n , Decca, airborne profile recorder ( A P R ) statoscope and gyroscope are g r a d u a l l y being improved. I believe, however, t h a t it is doubtful w h e t h e r t h i s i m p r o v e m e n t can also be obtained for the gyroscope. In t h i s respect I consider it necessalW to m a k e a few r e m a r k s r e g a r d ing t h i s subject. D u r i n g the 10 y e a r s since the w a r , m a n y e f f o r t s h a v e been m a d e to develop the gyroscope to a reliable precision i n s t r u m e n t which can solve the problem of orientation of the camera. E v e r y b o d y knows t h a t this, if it could be realized, would be of the u t m o s t importance f o r p h o t o g r a m m e t r y . We could m a k e a direct use of tilt a n d tip in rectifying, a s well a s improve the a c c u r a c y of radial t r i a n g u l a t i o n with these values or use t h e m for limiting t h e p r o p a g a t i o n of e r r o r s in aerial t r i a n g u l a t i o n in space. We all expected t h a t this powerful tool would be m a d e available. One of the results of this expectation w a s t h a t no more a t t e n t i o n w a s paid to the p r e - w a r m e a n s used for the s a m e purpose, in p a r t i c u l a r the horizon camera. The r e s u l t is t h a t only in the c o u n t r y in which the cradle of this horizon c a m e r a s t a n d s ( F i n l a n d ) t h e use of it h a s been f u r t h e r developed. The succesful use of the s a m e inst~mment in the N e t h e r l a n d s became impossible because of the loss of all Zeiss c a m e r a s with horizon d u r i n g t h e w a r [3]. We believe t h a t it h a s now become a n u r g e n t problem to take up a g a i n t h e horizon c a m e r a a n d develop it t o g e t h e r with the Santoni Solar Periscope as the m o s t reliable a n d precise m e a n s for the dete~mination of the elements of orientation d u r i n g exposure. F u t u r e e x p e r i m e n t s will show which of these two available tools is the best, i.e. which is t h e easiest to handle, the m o s t reliable a n d which gives t h e m o s t precise results. We hope t h a t in t h i s respect the next congress will show a g r e a t improvement. T h e f i r s t step would be to convince the f~ctories of the g r e a t i m p o r t a n c e of the horizon picture, in p a r t i c u l a r for aerial t r i a n gulation. W i t h some alteration of the p r e - w a r type it m i g h t even be extended in such a w a y t h a t also the P a l m e r a z i m u t h control of a strip could be obtained with the s a m e horizon camera. The resolutions proposed by Comm. I a n d accepted by the General A s s e m b l y as f a r as they are of a technical n a t u r e h a v e stressed in No. 5 the desirability to extend the tests on r e g i s t r a t i o n of the horizon to some countries which h a v e no experience so far. It is i m p o r t a n t t h e r e f o r e t h a t some f a c t o r y t a k e s ' u p a g a i n t h e t a s k to build a good horizon c a m e r a it/ order to enable those who believe in its value to fulfill the wish expressed in point 5 of the resolutions. 4. Comm. II. Instruments and methods of restitution. In 1. 2. 3.

Comm. II we can d i s t i n g h u i s h between v a r i o u s subjects. A n n o u n c e m e n t of new i n s t r u m e n t s . D e t e r m i n a t i o n of precision and a n a l y s i s of e r r o r s of i n s t r u m e n t s . Problems about relative and absolute orientation.

R e g a r d i n g new i n s t r u m e n t s we m u s t a d m i t t h a t the h a r v e s t is r a t h e r poor. There were p a p e r s about the P h o t o s t e r e o g r a p h N i s t r i Beta II and the Stereotop of Zeiss. These, however, are not new because t h e y were already exhibited in W a s h i n g t o n , a l t h o u g h it m u s t be borne in m i n d t h a t the Stereotop w a s s u b s t a n t i a l l y redesigned and t h a t also the Nistri Beta II is improved compared to the 1952-model. The s a m e holds good f o r several other i n s t r u m e n t s , even for the f i r s t - o r d e r m a c h i n e s of t h e classical type. I have sometimes the impression t h a t w i t h our plotting m a c h i n e s we go t h e s a m e w a y as with auto-

mobiles which e v e r y y e a r s h o w so-called i m p r o v e m e n t s , b u t which, f r o m the technical point of view are complications. A n o t h e r c o m p a r i s o n can be m a d e w i t h a m a t e u r c a m e r a s which are r e g u l a r l y i m p r o v e d in such a w a y t h a t a n o r m a l u s e r h a s so m a n y tricks on his camera, t h a t only in exceptional cases he can use it. The only f a c t which a l w a y s counts is the increase in price. A r e we g o i n g t h e s a m e w a y w i t h o u r p l o t t i n g m a c h i n e s ? Modern techniques can m a k e better i n s t r u m e n t s f o r less money. I n s t e a d of this, these techniques a r e used to add n e w a u x i l i a r y i n s t r u m e n t s to the e x i s t i n g types, k e e p i n g t h e i n s t r u m e n t s at best on the s a m e price, b u t sometimes m a k e t h e m m o r e expensive. I believe t h a t a b e t t e r solution would be to s i m p l i f y t h e i n s t r u m e n t s as m u c h as possible and m a k e t h e m available at a m o r e reasonable price. I t m a y be t h a t some d e s i g n e r s of the i n s t r u m e n t s and even some v i s i t o r s of the exhibits, who have a d m i r e d the i n g e n u o u s n e w tools on the i n s t r u m e n t s c a n n o t a p p r e c i a t e these r e m a r k s too well. I m u s t a d m i t t h a t n a t u r a l l y t h e y are not t r u e f o r all additional tools, because some of t h e m have a g r e a t influence on th~ efficiency of the i n s t r u m e n t and p a r t l y on the reliability of the results. The r e g i s t r a t i o n of the c o o r d i n a t e s is an example of an essential i m p r o v e m e n t , the value of which is m o s t a p p a r e n t on the S t e r e o t o p o g r a p h e Poivilliers type B., w i t h the r e a d i n g of the c o o r d i n a t e s on long v e r n i e r s a t an u n e a s y place in the older models. The mechanical coordinate r e g i s t r a t i o n of the Zeiss C8 w a s s h o w n ; it seems however, t h a t in the n e a r f u t u r e not only in the Wild A7 will it be possible to connect its r e c o r d i n g device w i t h a p u n c h e d c a r d p r i n t e r , b u t also in the Zeiss C8. These are i m p r o v e m e n t s which cost quite some money, b u t which have a f a v o u r a b l e influence on the efficiency of t h e entire p h o t o g r a m m e t r i c p l o t t i n g procedure. We believe however, t h a t t h i s c o m p u t i n g s y s t e m is also still in its e a r l y beginning. So f a r we used only t h e n o r m a l IBM punched card c o m p u t e r s . I t is an open question w h e t h e r the day will come t h a t w i t h an increased production of f i r s t - o r d e r p l o t t i n g m a c h i n e s and an increased application of the e n t i r e l y analytical m e t h o d in p h o t o g r a m m e t r y , a special c o m p u t i n g m a c h i n e will be designed which is in p a r t i c u l a r a d a p t e d to p h o t o g r a m m e t r i c w o r k and specially suitable f o r combination w i t h a f i r s t - o r d e r machine. We u n d e r s t a n d however, t h a t so f a r the use of conventional t y p e s which have a m u c h l a r g e r m a r k e t , is the c h e a p e s t solution f o r p h o t o g r a m m e t r i s t s . My critical r e m a r k , however, is m u c h m o r e directed t o w a r d s a n o t h e r e l e m e n t which is introduced n o w : the t r a n s m i s s i o n devices. So f a r we h a v e m a i n l y mechanical t r a n s missions. We c h a n g e the elements of o r i e n t a t i o n ~ a n d w and the base c o m p o n e n t s by m e a n s of s c r e w s and w o r m wheels w h i c h are moved b y f r e e hand. At the exhibition we have seen applications of electro-mechanical devices. N i s t r i s t a r t e d , as we know, w i t h the electrical t r a n s m i s s i o n and he h a s applied now the s a m e principle to his model B e t a I I in such a w a y t h a t the s c a n n i n g m o v e m e n t is c h a n g e d into the o p e r a t i o n of the steer wheel like in a car. Wild h a s a kind of column control f o r t h e s c a n n i n g m o v e m e n t on the A7 which is handled in a s i m i l a r w a y as the control column of an airplane. It. seems, however, t h a t this increases t h e price of the A7 w i t h a n a m o u n t of s o m e t h i n g like Sw. F r . 20.000.-- I doubt v e r y m u c h w h e t h e r t h i s kind of " i m p r o v e m e n t " c a n ever be justified f r o m a n economic point of view. I f I t h e n see t h a t f a c t o r i e s in t h e i r o f f e r s to countries, in w h i c h m a i n t e n a n c e of i n s t r u m e n t s a s such is a l r e a d y a problem, p r o p a g a t e all these remote control devices as i m p r o v e m e n t s , I d o u b t w h e t h e r it is really r i g h t to introduce in services, which are f a r a w a y f r o m the f a c t o r y , such e l e m e n t s which m a k e the i n s t r u m e n t m o r e v u l n e r a b l e a n d i n c r e a s e the chance t h a t it will be o u t of order. A l r e a d y the electrical r e g i s t r a t i o n of coordinates is difficult, enough. I do not t h i n k t h a t by m a k i n g the i n s t r u m e n t s in this direction still m o r e complicated we would r e n d e r a g r e a t service to m a n y institutes, n o r do I consider it necessary. A l t h o u g h the m o v e m e n t of b z and b v by f r e e h a n d in the S t e r e o p l a n i g r a p h r e q u i r e s some time, I p r e f e r , f r a n k l y s p e a k i n g , f o r the use in an o v e r s e a s c o u n t r y , the "old f a s h i o n e d " C8 above the C8 w i t h all these i m p r o v e m e n t s which a r e j u s t as m a n y w e a k spots. I f such a remote control is a n essen-

6 tial element in the design of i n s t l u m e n t s such as the v a n i s h i n g point control by electric drive on the Zeiss SEG V Rectifier, I can fully agree and I believe we m u s t t a k e the risk. If, however, it is only to avoid the f r e e h a n d m o v e m e n t of a bx-handwheel, we go too f a r because we replace an operation which does not cost v e r y much, by a risk. This does not count if we keep s i m u l t a n e o u s l y on the i n s t r u m e n t s the traditional possibilities for the movements, b u t t h e n t h e new elements will certainly have an i n c r e a s i n g influence on the price. I fully reMize a s I said before, t h a t not everybody will agree with these r e m a r k s w h i c h have the tendency t h a t in the design of i n s t r u m e n t s we m u s t d i s t i n g h u i s h between tools and toys. I accept the risk to he considered a n old-fashioned p h o t o g r a m m e t r i s t . The background of m y t h o u g h t s is only t h a t we m u s t p u t in the h a n d s of t h e m a n y n~w p h o t o g r a m m e t r i c services w i t h a n e n o r m o u s n u m b e r of h a r d l y t r a i n e d o p e r a t o r s i n s t r u m e n t s which are as simple as possible and which have no more complications t h a n necess a r y for an efficient solution of the problems. R e g a r d i n g i n s t r u m e n t s of the Multiplex and Kelsh types, we found t h a t N i s t r i h a s replaced his F o t o c a r t o g r a f o IV by No. V which m e a n s t h a t N i s t r i h a s abandoned the a d v a n t a g e of observation on the screen in t h e direction of the p r o j e c t i n g r a y s a n d now observes reflected i m a g e s f r o m a white painted screen like all Multiplex a n d s i m i l a r i n s t r u m e n t s . Also f r o m other points of view we believe t h a t the F o t o c a r t o g r a f o V is a n o t h e r type t h a n the F o t o c a r t o g r a f 0 IV. To a certain e x t e n t V is a simplification of IV, although also in t h i s i n s t r u m e n t we find, like in the Williamson L S P , the tendency to add all kinds of complications to t h e original simple t y p e of Kelsh plotter w i t h o u t changing a n y t h i n g in the f u n d a m e n t a l limitation of the capacity of t h i s i n s t r u m e n t which lies in its s y s t e m of observation of w h a t is sometimes called "dull-sighted" images. We believe t h a t the Kelsh plotter m u s t be kept as simple a s possible because t h i s is the g r e a t a d v a n t a g e of t h i s t y p e of i n s t r u m e n t . F r o m t h a t point of view I can accept the Gamble Plotter a s a real i m p r o v e m e n t on the multiplex i n s t r u m e n t s as f a r as t h e y are not used f o r bridging. The Gamble Plotter which projects a network of dots directly on the m a p sheet, gives the possibility to d r a w contour lines by f r e e h a n d directly on the map. We believe t h i s m u s t considerably improve the efficiency of plotting. This is a kind of i m p r o v e m e n t in one of the essential elements of the operation of a n i n s t r u m e n t and t h e r e f o r e t h e little complication of the device for projecting the grid of dots is fully acceptable. In the series of f i r s t - o r d e r i n s t r u m e n t s consisting (in alphabetical order) of the well-known Galileo-Santoni Stereocartografo IV, SOM-Poivilliers Stereotopographe Type B, Wild A u t o g r a p h A7 a n d Zeiss S t e r e o p l a n i g r a p h C8 we m u s t add N i s t r i ' s Fotostereog r a p h B e t a II which h a s now found its definite form. Still more justified to be considered a really new type is the T h o m p s o n W a t t s Plotter which w a s shown for the f i r s t t i m e to an i n t e r n a t i o n a l public a t t h i s conference. Both thes~ n e w i n s t r u m e n t s use the PorroKoppe s y s t e m b u t above all t h e T h o m p s o n W a t t s Plotter is based on a principle of design which is entirely d i f f e r e n t f r o m all e x i s t i n g i n s t r u m e n t s . We do not consider it n e c e s s a r y to go here into f u r t h e r details [4]. A special position is held by the new A u t o g r a p h Wild A9. The design of t h i s i n s t r u m e n t became n e c e s s a r y because none of the e x i s t i n g f i r s t - o r d e r m a c h i n e s can take photog r a p h s f r o m the Super Aviogon lens. T h i s A9 m u s t w i t h o u t a n y doubt be considered as a first-order plotting i n s t r u m e n t , n o t w i t h s t a n d i n g the f a c t t h a t the i n s t r u m e n t takes only p h o t o g r a p h s of h a l f the original size. T h i s a u t o g r a p h m u s t therefore be used in combination with the Wild U3 t r a n s f o r m e r . Because of this necessity it will be preferable to p u t correction plates for distortion in t h i s t r a n s f o r m e r a n d work in the A9 w i t h distortion-free diapositives. T h i s m a k e s it u n n e c e s s a r y to use in the i n s t r u m e n t itself a p a i r of c o m p e n s a t i n g plates which, due to t h e reduction of the size, would require twice the precision of the n o r m a l c o m p e n s a t i n g plates. The new Wild A9 A u t o g r a p h not only t a k e s p h o t o g r a p h s m a d e with the super wide angle, b u t also w i t h all kinds of n o r m a l wide-angle cameras. }~ecause the r a n g e of prin-

cipal d i s t a n c e is b e t w e e n 40 a n d 77 m m , t h e A9 does n o t t a k e t h e n o r m a l s t a n d a r d a n g l e p h o t o g r a p h s w i t h p r i n c i p a l d i s t a n c e s l a r g e r t h a n 150 m m . ( W e do n o t c o n s i d e r a 3 X r e d u c t i o n o f t h e n e g a t i v e s in o r d e r to become a p r i n c i p a l d i s t a n c e s m a l l e r t h a n "/7 m m as a n acceptable solution.) T h e A 9 is a good e x a m p l e of t h e p r e s e n t t e n d e n c y to c r e a t e i n s t r u m e n t s f o r special p u r p o s e s . W e believe t h a t in f u t u r e t h e i m p o r t a n t p h o t o g r a m m e t r i c services will h a v e a t t h e i r d i s p o s a l a c e r t a i n v a r i e t y of i n s t r u m e n t s o f w h i c h e a c h is a d a p t e d to t h e solution of a special problem. A n o t h e r n e w i n s t r u m e n t is t h e S O M - B a b o z Stereophot. I t is a s e c o n d - o r d e r p l o t t e r with l i m i t e d precision. I t is second o r d e r b e c a u s e it realizes g e o m e t r i c a l l y s p e a k i n g , a p e r f e c t solution. T h e a i m o f t h i s i n s t r u m e n t is to s i m p l i f y t h e s y s t e m of o b s e r v a t i o n to a t y p e of f i x e d m i r r o r stereoscope. T h e r e f o r e a f l o a t i n g m a r k in t h e f o r m o f a l i g h t spot is p r o j e c t e d in t h e p l a n e o f t h e n e g a t i v e s . T h i s p r o j e c t i o n is c a r r i e d o u t in a d i f f e r e n t w a y t h a n in t h e K u y p e r s L i g h t Spot P l o t t e r , b u t t h e u s e of t h i s p r i n c i p l e of p r o j e c t i n g a light s p o t in t h e p l a n e of t h e n e g a t i v e , w h i c h goes b a c k to P r 6 d h u m e a u in 1926, b o t h i n s t r u m e n t s h a v e in c o m m o n . T h e S t e r e o p h o t c o m b i n e s t h i s idea w i t h a m e c h a n i c a l projection a n d t h e K u y p e r s P l o t t e r w i t h a n optical projection. B a b o z f o u n d a n i n g e n u o u s solution f o r t h e i n t r o d u c t i o n of t h e e l e m e n t s o f r e l a t i v e o r i e n t a t i o n b y m e a n s of r o t a t i o n of a s m a l m i r r o r , t h e c e n t r e o f r o t a t i o n of t h e collimators. A w e a k n e s s o f t h i s i n s t r u m e n t is t h a t so f a r t h e stereoscope h a s o n l y two t i m e s e n l a r g e m e n t . W e believe t h i s e n l a r g e m e n t is d e t e r m i n e d b y t h e size of t h e l i g h t s p o t in t h e p l a n e o f t h e n e g a t i v e , w h i c h is t h e i n t e r s e c t i o n of t h i s p l a n e w i t h a b u n d l e of p a r a l l e l l i g h t c o m i n g f r o m a l i g h t s o u r c e in t h e focal p l a n e of t h i s collimator. I t m a y be t h a t t h i s s m a l l m a g n i f i c a t i o n l i m i t s t h e possibilities of a p p l i c a t i o n o f t h i s r e m a r k a b l e i n s t r u m e n t . T h e solution o f t h e p r o b l e m o f t h i r d - o r d e r i n s t r u m e n t s s e e m s to be r a t h e r difficult. T h i s c a n be d e r i v e d f r o m t h e f a c t t h a t no n e w s o l u t i o n s f o r t h i s p r o b l e m w e r e s h o w n in Stockholm. T h e r e w e r e a g a i n t h e Z e i s s Stereotop, t h e N i s t r i Model 90 S t e r e o g r a f o m e t e r a n d G a l i l e o - S a n t o n i C a r t o g r a p h i c S t e r e o m i c r o m e t e r . M u c h a t t e n t i o n h a s been paid to t h e s e i n s t r u m e n t s d u r i n g t h e exhibition. T h a t is f o r o b v i o u s r e a s o n s : m a n y i n s t i t u t e s , w h i c h need a g r e a t n u m b e r of i n s t r u m e n t s m e e t d i f f i c u l t i e s w i t h t h e cost of i n v e s t m e n t , l~ecessary e v e n f o r s e c o n d - o r d e r m a c h i n e s . T h e y a r e all w a i t i n g f o r t h i r d - o r d e r p l o t t i n g i n s t r u m e n t s w h i c h c a n be b o u g h t a t a r e a s o n a b l e price. W e h a v e t h e i m p r e s s i o n , h o w e v e r , t h a t t h e v a r i o u s s o l u t i o n s of t h i s p r o b l e m , w h i c h so f a r a r e n o t m o r e t h a n p r o j e c t s on p a p e r , will come a s f a r a s t h e i r p r i c e s a r e concerned, too close to t h e s i m p l e s t possible v e r s i o n of a K e l s h P l o t t e r . T h e cost o f t h e e x i s t i n g t h i r d - o r d e r i n s t r u m e n t s ( t h i r d - o r d e r b e c a u s e of t h e a p p r o x i m a t e solution by it) w h i c h lies b e t w e e n P o u n d S t e r l i n g 800 a n d 1000 m a y be r e a s o n a b l e , b u t is still a l a r g e a m o u n t of m o n e y . T h e s e i n s t r u m e n t s , h o w e v e r , c a n in m a n y c a s e s r e n d e r e x c e l l e n t services. It w o u l d be desirable, t h a t a c o m p l e t e t h e o r y of t h e s e i n s t r u m e n t s w e r e be p u b l i s h e d in o r d e r to d e t e r m i n e t h e i r l i m i t a t i o n s . T h e y a r e n o t u n i v e r s a l a n d it is w e l l - k n o w n t h a t a c o m b i n a t i o n of a c o n s i d e r a b l e tilt o f t h e optical a x i s of abt. 3 d e g r e e s a n d l a r g e d i f f e r e n c e s in h e i g h t in t h e t e r r a i n c a n c a u s e e r r o r s in h e i g h t Which a r e f a r above t h e n o r m a l t o l e r a n c e s . W e believe, h o w e v e r , t h a t t h e u s e of t h e s e i n s t r u m e n t s will become still m o r e g e n e r a l a n d t h a t t h e i r p r e s e n t l i m i t a t i o n c a n be overcome a s soon a s we c a n d e r i v e t h e tilt f r o m f o r i n s t a n c e h o r i z o n p i c t u r e s a n d as soon as we h a v e a u n i t r e c t i f i e r a t o u r d i s p o s a l w h i c h p r o v i d e s u s w i t h d i a p o s i t i v e s or print~ on n o n - s h r i n k a b l e m a t e r i a l on t h e scale of t h e o r i g i n a l n e g a t i v e , b u t w h i c h a r e rectified. H e r e a g a i n we m e e t a r e a s o n w h y t h e c o n s t r u c t i o n of a good horizon c a m e r a is one of t h e m o s t u r g e n t n e e d s in p h o t o g r a m m e t r y . T h a t t h e stereoscopic o b s e r v a t i o n is still a c o n t i n u o u s s u b j e c t of s t u d y a n d e f f o r t s for i m p r o v e m e n t w a s p r o v i d e d by t h e p a p e r s a t t h i s c o n g r e s s . T h e m o s t i m p o r t a n t w a s p e r h a p s t h a t of Mr. Y z e r m a n , " t h e SDI, a n e w m e t h o d f o r stereoscopic m e a s u r e m e n t s a n d p l o t t i n g " , a m e t h o d of o b s e r v a t i o n developed by Mr. Y z e r m a n d u r i n g his period of s t u d y a t t h e I T C on a K e l s h P l o t t e r . H i s m e t h o d p r o m i s e s a p r e c i s i o n w h i c h a h ' e a d y in

8 t h e o r y is twice t h a t of t h e n o r m a l stereoscopic o b s e r v a t i o n . Mr. Y z e r m a n p r o v e d in h i s p r e s e n t p o s i t i o n in t h e K e r n f a c t o r y , in S w i t z e r l a n d , t h a t h e o b t a i n e d on a n i n s t r u m e n t of t h e m i r r o r s t e r e o s c o p e - t y p e a n a v e r a g e d e c r e a s e o f t h e m e a n s q u a r e e r r o r in h e i g h t of 50% by m e a n s of h i s Stereo D i r e c t I n v e r s e e q u i p m e n t . W e c o n s i d e r t h e a p p l i c a t i o n of t h i s p r i n c i p l e of s u f f i c i e n t i m p o r t a n c e to c a r r y o u t f u r t h e r e x p e r i m e n t s in t h i s direction. E s p e c i a l l y f o r t h e M u l t i p l e x - t y p e of i n s t r u m e n t s t h i s could be of i m p o r t a n c e , a l t h o u g h h e r e it is also t r u e t h a t t h e a d d i t i o n of a n electrical device m a k e s t h e i n s t r u m e n t m o r e v u l n e r a b l e . F u r t h e r m o r e we d r a w t h e a t t e n t i o n to a n i m p o r t a n t article b y P r o f . B a e t s l 6 f r o m B e l g i u m r e g a r d i n g t h e a p p a r e n t e x a g g e r a t i o n of t h e relief in stereoscopic observation. He comes to t h e conclusion t h a t c o o p e r a t i o n o f p h o t o g r a m m e t r i s t s a n d p h y s i o l o g i s t s is n e c e s s a r y in o r d e r to come to a b e t t e r solution t h a n a t p r e s e n t . R e g a r d i n g t h e second g r o u p of s u b j e c t s " T h e d e t e r m i n a t i o n of p r e c i s i o n a n d a n a l y s i s of e r r o r s of i n s t r u m e n t s " o n l y a f e w p a p e r s w e r e p r e s e n t e d . I n t h e Geodetic I n s t i t u t e of t h e U n i v e r s i t y of M i l a n a s i m i l a r r e s e a r c h a s c a r r i e d o u t b y v. d. W e e l e in D e l f t d u r i n g t h e w a r on two s t e r e o p l a n i g r a p h s , w a s p u b l i s h e d f o r a S a n t o n i S t e r e o c a r t o g r a f o IV. In t h e conclusion t h e a u t h o r s g i v e p r o v i s i o n a l v a l u e s of t h e m e a n p r o j e c t i o n e r r o r s o b t a i n e d f r o m t e s t s c o n d u c t e d d u r i n g p l o t t i n g m~ = 6 ~ my = 4 ~, ml~ = 0.080/00 of t h e f l y i n g h e i g h t . It is r e g r e t t a b l e h o w e v e r , t h a t t h e y do n o t i n d i c a t e w h a t k i n d o f p l o t t i n g t h i s h a s been, w h e t h e r it is a c e r t a i n t y p e of p h o t o g r a p h y or w h e t h e r it is t h e p l o t t i n g Gf g r i d s , w h i c h m a k e s a g r e a t d i f f e r e n c e . T h e f i g u r e s give m e t h e i m p r e s s i o n t h a t t h e y a r e derived from grid measurements. S e v e r a l S w e d i s h p u b l i c a t i o n s a r e b a s e d on t h e m e t h o d s as described b y H a l l e r t f o r t h e d e t e r m i n a t i o n of r a d i a l d i s t o r t i o n . H a l l e r t a n d R a i n l u n d m a k e a s u g g e s t i o n f o r a s t a n d a r d i z e d t e s t of t h e p r o j e c t i o n s y s t e m in p h o t o g r a m m e t r i c p l o t t i n g i n s t r u m e n t s in w h i c h t h e y also e x p r e s s t h e e r r o r s of p r o j e c t i o n in a k i n d of r a d i a l d i s t o r t i o n curve. A f t e r t a k i n g into a c c o u n t , h o w e v e r , t h e i n f l u e n c e of t h e x - i n c l i n a t i o n a n d t h e l a t i t u d e d i s t o r t i o n in t h e AT, t h e r e w a s n o t h i n g l e f t b u t a n i r r e g u l a r line w h i c h s h o w s n e g l i g i b l e e r r o r s . It is d o u b t f u l w h e t h e r it h a s a n y s e n s e to e x p r e s s p r o j e c t i o n e r r o r s in t h i s c a s e in t h e f o r m of a r a d i a l d i s t o r t i o n . T h e i n f l u e n c e o f l a c k of i n t e r s e c t i o n o f g i m b l e a x i s etc. will n o t show u p in a c i r c u l a r f o r m a r o u n d t h e n a d i r line, a l t h o u g h t h e f l e x i o n of s p a c e r o d s of a s y s t e m of m e c h a n i c a l p r o j e c t i o n m a y be t h e c a u s e of t h i s t y p e o f d e f o r m a t i o n . F u r t h e r ~ m o r e I do n o t believe t h a t it is j u s t i f i e d to s u b t r a c t t h e i n f l u e n c e o f x - i n c l i n a t i o n a n d l a t i t u d e d i s t o r t i o n in a n A7 f r o m t h e d e f o r m a t i o n s in t h e pencil of r a y s . T h e m e t h o d i n d i c a t e d by L y c k e n f o r t h e d e t e r m i n a t i o n of t h e s e e r r o r s is excellent. It will be n e c e s s a r y , however, to i n c l u d e t h e i n f l u e n c e of t h e r e s i d u a l e r r o r s o f t h e a d j u s t m e n t of x - i n c l i n a t i o n a n d l a t i t u d e d i s t o r t i o n in t h e f i n a l d i a g r a m of e r r o r s in a g r i d m e a s u r e m e n t a s u s u a l in n o r m a l practice. T h e s t u d y of H o t h m e r a b o u t e r r o r s in g i m b a l a x i s is v e r y u s e f u l b e c a u s e it g i v e s a n u m e r i c a l i m p r e s s i o n a b o u t t h e i n f l u e n c e of t h e e r r o r s in one of t h e m o s t v i t a l e l e m e n t s of all p h o t o g r a m m e t r i c r e s t i t u t i o n m a c h i n e s . H i s d i a g r a m s c a n help to f i n d a d i a g n o s i s in t h e e v a l u t i o n of r e s u l t s of g r i d m e a s u r e m e n t s . I a g r e e f u l l y w i t h h i s w a r n i n g t h a t a n o r m a l u s e r of a n i n s t r u m e n t s h o u l d n o t s t a r t w i t h c o r r e c t i o n s of g i m b a l axis. T h e t h i r d p a r t of t h e p u b l i c a t i o n s in t h i s section d e a l s w i t h t h e p r o b l e m s of r e l a t i v e a n d a b s o l u t e o r i e n t a t i o n . T h e y a r e m a i n l y S w e d i s h , all b a s e d on t h e f u n d a m e n t a l w o r k of H a l l e r t w h i c h w a s d e m o n s t r a t e d in a g r e a t n u m b e r of p u b l i c a t i o n s , a p a r t of w h i c h h o w e v e r w a s a l r e a d y k n o w n f r o m p u b l i c a t i o n s in v a r i o u s periodicals in t h e p a s t . N e v e r t h e l e s s p a r t 4 of Vol. X I I g i v e s a v e r y good r e v i e w a b o u t t h i s i m p o r t a n t S w e d i s h work. O n e of t h e r e s o l u t i o n s o f C o m m . II, a c c e p t e d b y t h e G e n e r a l A s s e m b l y w a s a b o u t t h e r e q u e s t to f a c t o r i e s a n d a u t h o r s to a c c e p t a s t a n d a r d i z e d c o o r d i n a t e s y s t e m . T h e a p p r o v a l of t h i s p r o p o s a l is of p r a c t i c a l v a l u e a n d we will e x p l a i n t h e c o n s e q u e n c e s in a special s h o r t a r t i c l e in t h i s review.

9 5. Comm. III. Aerial triangulation and its application to geodesy. If we s t a r t h e r e with radial triangulation we meet f i r s t a new Wild Radial Triangulator according to the design of Roelofs. In this publication Roelofs studies the systematic errors i n scale- and azimuth t r a n s f e r , using as a measure of comparison the standard accidental errors of aerial triangulation in space. It is proved t h a t the former are generally much smaller than the latter, a p a r t from a few exceptional cases of topography. The drawback naturally is, t h a t it gives only two coordinates. In flat or almost flat terrain, ilowever, the third coordinate will never have sufficient precision if we use aerial survey in an economic way. Therefore in all those cases radial triangulation can be excellent for the determination of the planimetric control. The appearance of this precision radial triangnlator again laid stress on the necessity to develop f u r t h e r means for the determination of the n a d i r point either by horizon cameras of special design or by means of the soiar periscope. Fagerholm f r o m Sweden continued his efforts to increase the precision of the slotted templet'method. In the Swedish exhibit prototypes were shown for f a s t and accurate point t r a n s f e r and for templet slottingi Not only in Sweden but also in Austria efforts are made for the design Of a stereoscopic i n s t r u m e n t for the t r a n s f e r Of points f r o m one photograph to the otiaer. These instruments must r e p l a c e the classical, now over 20 year s old Dutch method to t r a n s f e r such points by the use of floatifig marks which are moved by free,hand. Several Dutch investigations have shown t h a t this can be executed with a mean square error of 0.02--0.03 r a m . According to the experience we obtained with the device for stereoscopic t r a n s f e r in the radial,.triangulator of 1935 built by de Koningh, it is doubtful whether this precision can be increased considerably [5]. All movable mechAnical p a r t s are sources Of errors which very easily surpass a few hundredths of a millimeter. Regarding the a d j u s t m e n t of aerial triangulation again a n u m b e r Of p'ublications, dealing with the compensation of single strips according to the method of least squares, were presented. I have the impression t h a t f u r t h e r development along this line, a f t e r what is known so far, has not much sense. A long single strip has a very weak structure. The improvement of it b y - m e a n s of a perfect method of compensation does not change the principle of this structure. Moreover it is questionable whether there i s a good proportion between this improvement and the ,cost in time and money of such a C0mpensation: We believe therefore t h a t with aerial triangulation the same wilt happen as with the traverse in groilnd survey: in almost all' c~ases we are satisfied with an approximate method'of adjustment. The method published by the French IGN at the 1952 Washington Congress is a very satisfactory parallel with the computation of~ a normal traverse. There is f i r s t an a d j u s t m e n t of the elements of orientation by linear distribution of the closing errors. Based on these adjusted elements of orientation the closing e r r o r s in coordinates are computed and then these errors are distributed along the strip by means of a secondorder binomium. Another well-known example is the graphical method of Zarcicky, Van tier Weele tried successfully to simplify the least square method of adjustmen t by deriving the coefficients of the third-order binomium of the correction equation f r o m the seven closing errors of a strip which equation was based on the publication of Roelofs~ of 1952 in this review. We have the impression, however, t h a t a least square method for the adjustment of a strip limits its practical value to the derivation of the correction formula$ as carried out by Roelofs and of the mean square errors in the compentated coordinates. The various publications show t h a t they all come to the same result but along d i f f e r e n t lines: a third-order correction curve. I personnaly like the method of Vermeir which, in particular f o r long strips, gives a very rapid solution for the principal points. Corrections for points outside the centre line of the strip can be found by interpolation. This may be an approximation: we believe, however, t h a t this method which in this way takes only a very short time will give satisfactory results [6].

10 If we r e a l l y w i s h to a p p l y t h e m e t h o d of l e a s t s q u a r e s we m u s t n o t consider t h e s t r i p but each individual photograph with its surrounding overlaps and express the conditions f o r each of t h e c o m m o n p o i n t s , b o t h in t h e s a m e s t r i p a n d in t h e a d j a c e n t s t r i p s . W e know, h o w e v e r , t h a t t h i s m e t h o d r e s u l t s in s u c h a n u m b e r of condition e q u a t i o n s , t h a t t h e solution of t h i s s y s t e m , e v e n w i t h electronic c o m p u t i n g m a c h i n e s , is v e r y difficult. W e believe t h a t V a n d e r W e e l e in t h i s c o n g r e s s m a d e a c o n t r i b u t i o n to a v e r y p r a c t i cal a n d , also f r o m t h e t h e o r e t i c a l p o i n t o f view, s o u n d solution. H e f o r m s blocks o f a l i m i t e d n u m b e r of p h o t o g r a p h s , f o r i n s t a n c e 3 s t r i p s of 7 p h o t o g r a p h s each, or 4 s t r i p s w i t h 9 p h o t o g r a p h s , d e p e n d i n g on t h e r e q u i r e m e n t of precision. T h e s e s h o r t s t r i p s a r e c o n n e c t e d w i t h each o t h e r b y l i n e a r t r a n s f o r m a t i o n . T h e i n t e r n a l e r r o r s o f each o f t h e s e little blocks c a n be n e g l e c t e d a n d t h e a v e r a g e of t h e two v a l u e s of t h e c o o r d i n a t e s o f c o m m o n p o i n t s a r e u s e d inside e a c h s m a l l block. V a n d e r W e e l e p r o p o s e s to m a k e t e m p l e t s f o r e a c h of t h e s e blocks a c c o r d i n g to t h e m e t h o d of t h e s t e r e o t e m p l e t s p r o p o s e d b y s o m e A m e r i c a n a u t h o r s . A slotted t e m p l e t l a y - o u t of t h e s e blocks will p r o v i d e u s w i t h a m e c h a n i c a l a d j u s t m e n t of t h e w h o l e block. I f t h e "errors c a u s e d b y t h e u s e of t h e m e c h a nical m e a n s f o r t h e slotted t e m p l e t l a y - o u t a r e n o t a c c e p t a b l e it is possible to a p p l y a l e a s t s q u a r e block a d j u s t m e n t on a s e t of s u c h blocks. T h e i n t r o d u c t i o n o f s u c h blocks m e a n s t h e n t h a t we g r e a t l y l i m i t t h e n u m b e r of c o n d i t i o n e q u a t i o n s a n d t h a t t h e l e a s t s q u a r e a d j u s t m e n t m e t h o d c o m e s p e r h a p s w i t h i n t h e r a n g e of p r a c t i c a l possibilities. W e believe t h a t in a d d i t i o n to t h e e x i s t i n g m e t h o d s f o r block a d j u s t m e n t s u c h a s t h a t o f Zeller, it will be d e s i r a b l e to c a r r y o u t f u r t h e r e r p e r i m e n t s w i t h block a d j u s t m e n t s a l o n g t h e s e lines. A r e m a r k a b l e m e t h o d f o r a d j u s t m e n t of h e i g h t s w a s o f f e r e d to t h e c o n g r e s s b y t h e F r e n c h I G N . I t is a p a r a l l e l of t h e slotted t e m p l e t m e t h o d s f o r h e i g h t s , viz. a m e c h a n i c a l solution. W e h a v e t h e i m p r e s s i o n , h o w e v e r , t h a t t h e e x e c u t i o n of t h i s m e c h a n i c a l c o m p e n s a t i o n is less s i m p l e t h a n t h e s l o t t e d t e m p l e t f o r p l a n i m e t r y . R e g a r d i n g t h e m e a n s to d e t e r m i n e s o m e o f t h e e l e m e n t s Of a b s o l u t e o r i e n t a t i o n o f e a c h e x p o s u r e we h a v e to m e n t i o n f i r s t a C a n a d i a n p u b l i c a t i o n in t h e C o n g r e s s ~ u m ] 0 e r of " P h o t o g r a m m e t r i a " w h i c h g i v e s a d e s c r i p t i o n of t h e methQd of P a l m e r w h i c h t r i e s to keep t h e f l e x i o n in a z i m u t h o f each s t r i p u n d e r control. A t e a c h 5 t h e x p o s u r e o f a v e r t i c a l p h o t o g r a p h h e t a k e s a low obliclue of t h e h o r i z o n on i n f r a r e d film. On t h i s h o r i z o n photo= g r a p h a s t r a i g h t line is i d e n t i f i e d b y m e a n s o f a point, close to t h e h o r i z o n a n d a n o t h e r p o i n t close to t h e n a d i r of t h e p h o t o g r a p h . T h i s line is t r a n s f e r r e d to t h e n e x t low oblique p h o t o g r a p h a n d to all v e r t i c a l p h o t o g r a p h s a n d k e e p s t h e y - v a l u e in e a c h s t r i p u n d e r control. T h e r e m a r k a b l e a c c u r a c y o b t a i n e d in a s t r i p of 120 k m , w h i c h g a v e a m a x i m u m e r r o r in y - d i r e c t i o n o f 7.9 m a n d of 15.3 m in a n o t h e r s t r i p o f 250 k m , is a n i n d i c a t i o n o f t h e g r e a t v a l u e of t h i s m e t h o d . T h i s p u b l i c a t i o n b r i n g s u s a g a i n to t h e g r e a t i m p o r t a n c e of h o r i z o n p h o t o g r a p h y . W e i n d i c a t e d t h i s a l r e a d y in s e v e r a l places in t h i s c o n g r e s s r e p o r t a n d w e h a v e to m e n t i o n in t h i s r e s p e c t in p a r t i c u l a r t h e r e s u l t s o b t a i n e d b y t h e F i n n i s h M i l i t a r y Topog~-aphic Service a s g i v e n in t h e N a t i o n a l R e p o r t of F i n l a n d a n d as will be e x p l a i n e d in a special a r t i c l e b y Lt. Col. L S f s t r S m in t h i s review. P h o t o g r a p h y o b t a i n e d w i t h old p r e w a r Z e i s s P-10 T o p o g o n c a m e r a s i n t h e scale o f 1 : 40,000 in s t r i p s of a l e n g t h o f 20 k m w i t h full control on b o t h e n d s w e r e t r i a n g u l a t e d in a p r e w a r S t e r e o p l a n i g r a p h . T h e a v e r a g e m e a n ~ q u a r e e r r o r in h e i g h t w a s b e t w e e n 2.0 a n d 2.5 m a n d in x- a n d y = c o o r d i n a t e s b e t w e e n 3 a n d 4 m. T h i s is w i t h o u t a n y d o u b t a r e m a r k a b l e r e s u l t w h i c h is d u e to t h e u s e of t h e h o r i z o n c a m e r a w h i c h , in t h i s case, e n a b l e d i t s u s e r to d e t e r m i n e t h e e l e m e n t s of o r i e n t a t i o n w i t h a m e a n s q u a r e e r r o r of abt. 3 c e n t e s i m a l m i n u t e s , w h i c h is a b o u t 1 : 2,000. There was not very much news about the direct determination of the coordinates of :the e x p o s u r e s t a t i o n b y electronic m e a n s . Dr. Z a r c i c k y e x p l a i n e d a g a i n in a v e r y good p a p e r t h e a p p l i c a t i o n o f S h o r a n to e s t a b l i s h h o r i z o n t a l c o n t r o l f o r p h o t o g r a m m e t r i c m a p p i n g in i n a c c e s s i b l e a r e a s . AS f a r a s r e s u l t s a r e m e n t i o n e d h e g i v e s a m e a n s q u a r e e r r o r of abt: 20 m in t h e position of a n a d i r p o i n t in a f l i g h t line; a b o u t h a l f t h i s v a l u e

11 if a certain point in the t e r r a i n is tied in between two trig. stations. Regarding theoretical block adjustments a remarkable article of the Belgium professor Baetsl~ "Compensation des blocs photogramm~triques en altim~trie p a r relaxation" must be mentioned. A very important p a r t of the activities of Comm. III was devoted to two closely related experiments. The f i r s t was t h a t r e g a r d i n g the "essai contrSl~" (controled experiment) No. 1 organized by the International Society of P h o t o g r a m m e t r y as a consequence of a resolution of the 1952 congress. Although this resolution originally expressed something of a spirit of competition of methods and instruments, the meeting of Comm. II, III and IV in 1954 in Gunten, Switserland, changed this character into t h a t of a controled experiment. The French IGN has made a g r e a t e f f o r t to make these experiments a success. The f i r s t dealth with aerial triangulation over a Swiss t e r r i t o r y "Hutwil" (50 X 50 km). Photographs were taken with an automatic plate camera Poivilliers SOM ~ f 125 ram. The area was covered with 7 strips of abt. 15-18 photographs each. A t the edges and in the middle were cross s t r i p s . Scale of photography 1 : 50,000. So f a r only results of the French IGN have been published. These results however, are of a remarkable high quality. The method of triangulation was t h a t published by the IGN a t the 1952 Congress. Computation was carried out in different ways, with and without the use of the cross strips, with complete numerical treatment, with mechanical compensation with stereotemplets for planimetry and with the mechanical adjustment of heights according to Masson d'Autume. The most remarkable results were obtained by the method which uses none of the cross strips and full control at the ends of all filling strips with one isolated point in the middle of three strips and as additional height control one series of points in the middle of all filling strips. The mean square errors in planimetry are m~ ~ 2.83 m, m x = 2.95 m and m z = 3.72 m. The method with cross strips gives for these values 3.31 m, 2.89 m and 3.43 m. A f t e r the mechanical compensation of heights this last figure was reduced to 2.56 m. In this case the o n l y ground control consisted of three pairs with full control at the ends and in the middle of each cross strip. These r e s u l t s w e r e obtained from photographs on glass plates without the use of any auxiliary instrument. All observations were carried out in the Stereotopograph type B. applying the Porro Koppe system with the use of the original negatives. This result proves t h a t on 2500 sq.km with only 9 pairs with full ground control results can be obtained which are entirely sufficient for a 1:20,000 topographic map. This shows w h a t can be reached with a system of photog r a p h y and restitution which is organized as one complete chain, in which all links have the same strength. It is not in particular the quality of instruments or operators, but the result of a perfect organization taking good care of all details of the complete procedure. We believe t h a t this consideration is not always taken into account. The second experimental triangulation which was introduced to the congress was t h a t of the European Organization for Experimental Photogrammetric Research (OEEP E ) . This European organization published in " P h o t o g r a m m e t r i a " a special report regarding its activities. The Congress was informed about programme and progress of this organization. There were, however, still no results available. They will be published in a future number of P h o t o g r a m m e t r i a a f t e r a thorough study of the f i r s t computations by the scientific committee, dealing with aerial triangulation in this organization. Its value has been explained sufficiently in this review and therefore it is not necessary to repeat t h a t the advantage of its activity is t h a t we, for the f i r s t time in the history of photogrammetry, will obtain a g r e a t quantity of figures and results based on material and observations which can really be compared. P e r h a p s it is also for the f i r s t time t h a t not only the good results, but a l l results, good and bad, will be discussed and later on published.

12 6. Comm. IV. Application of Photogrammetry and aerial photography for surveying the earth's surface. In the meetings of Comm. IV the results were presented obtained by applying photo~ g r a m m e t r y to the production of maps. The task of this commission was distributed over three subcommissions: the f i r s t dealt with the application to cadastral surveys, reporter Dr. H[irry from Switzerland, the second with the application to the survey of urban areas, reporter Dr. Dubuisson from F r a n c e and the third with the production of topographic maps, reporter Prof. Dr. Bachmann._ The f i r s t subcommission obtained important results from various institutes which took p a r t in the comparative mapping of the testfield Oberriet in Switserland with groundcontrol points of very high precision which was made available by the Swiss Federal Cadastral Service with the assistance of the Wild Factory. The same material consisting of photographs in d i f f e r e n t scales on film and plates were used by Comm. C of the O E E P E . The r e p o r t on the work, until t h a t moment achieved by Comm. C was presented by Prof. G. Lehmann from Hannover. This report, however, did not contain more than the programme of work, the regulations for the execution without indication of the results in time and precision. Much more important was the report of Dr. Hfirry who published results obtained by four different institutes: the Photogrammetric Institute in Jerusalem, Rikets Alm~nna Kartverk Stockholm, Kungl. Landm~iteristyrelsen, Stockholm and the National Photogrammetric Research Institute in Ottawa. F u r t h e r m o r e Prof. Hallert from the Royal Technical University in Stockholm has carried out with the same material certain experiments to solve special problems. The value of this test field lies partly in the very high precision of the ground control points which have a mean square e r r o r in position of 0.5 cm and in height of 0.47 cm. F o r the determination of the accuracy of photogrammetric restitution such a high precision of the test points is necessary. One important result mentioned by Dr. H~irry is t h a t the identification of boundaries between parcels which are not indicated by stones, shows errors between 10 and 15 cm. These differences are larger than in accordance with the precision of photogrammetric plotting. This is a result which confirms my own experience already published over 20 years ago. It means t h a t the full capacity of photogrammetric plotting in cadastral surveys can only be achieved in cases in which the boundaries are marked by stones and signalized. In all other cases the precision of our instruments will not be used to its utmost. I m p o r t a n t are also the comparisons with d i f f e r e n t sizes of signals. Regarding this problem we mention the experiments carried out in A u s t r i a by Hlawaty and Stickler with signals of different size, different colours on different background. Comparison of the result of the Oberriet area as mentioned in Dr. H~irry's report with the Austrian result shows t h a t it is highly worthwhile to continue these A u s t r i a n experiments. Regarding the computation of the results, Dr. H~irry mentions t h a t all participating centres have computed the coordinates of all signalized points by means of a linear t r a n s formation. Dr. Hfirry is for cadastral photogrammetry, in which the relative precision is of still more importance than the absolute precision of the position of points, in favour of the application of an affine transformation, dividing the surface a r e a of each pair into triangles. The advantage in t h i s case will be t h a t the residual errors in the control points will be zero and t h a t disagreeable discrepancies between adjacent pairs are practically avoided. Regarding precision, Dr. Hfirry computed, independently from the participating centres, the mean square e r r o r in planimetry and height for each pair. This was possible because the number of test points in each pair was sufficient viz. between 19 and 231. A study of his statistics however shows t h a t it is r a t h e r dangerous to d r a w conclusions from his figures. The mean square e r r o r in coordinates m R is reduced to the value m c in the plane of the negative. He finds values between 9 and 21 ~. Dr. H ~ r r y computed

~3 f u r t h e r m o r e the m e a n s q u a r e e r r o r m d in distances of points between 2 a n d 30 m a n d found as an a v e r a g e f o r m a = 0.496 X m~. T h i s proves t h a t the accuracy of the relative position of points is m u c h h i g h e r t h a n in the coordinates. This is of the u t m o s t i m p o r t a n c e for the application of p h o t o g r a m m e t r y to c a d a s t r a l surveys. A f u r t h e r conclusion which is n o t too dangerous, is t h a t the m e a n s q u a r e e r r o r m c decreases with the scale. Dr. H i i r r y gives f o r the scale 1 : 6,000 m c = 15 .~ which value decreases r e g u l a r l y to 11 ~t for the scale 1 : 21,500. A n o t h e r r e s u l t is t h a t about the precision of t h e d e t e r m i n a t i o n of heights. F o r the restitution of A v i o t a r p h o t o g r a p h s in f i r s t - o r d e r machines, Dr. H~irry found 0.120/00 of z for film a n d 0.1150/0 o for plates, with r e s t i t u t i o n in first-order machines. F o r the Aviogon 10 cm these f i g u r e s a r e in f i r s t - o r d e r m a c h i n e s 0.165O/o o a n d in second-order i n s t r u m e n t s 0.196°/00 of ~. Dr. H~irry f i n i s h e s h i s report w i t h a few s u g g e s t i o n s which should be t a k e n into account when continuing the experiment. One of these is t h a t for t h e comparison of film and plates it will be n e c e s s a r y to use two d i f f e r e n t c a m e r a s u n d e r the s a m e c i r c u m s t a n c e s , which in o u r opinion m e a n s t h a t we m u s t use t h e m s i m u l t a n e o u s l y in the s a m e plane. A f u r t h e r r e m a r k of Dr. H~irry is t h a t increase in a c c u r a c y can be expected f r o m the use of convergent p h o t o g r a p h y with 100% overlap in each pair. Both Dr. H~irry a n d the a u t h o r of t h i s article h a v e been in f a v o u r of the use of t h i s s y s t e m f o r m a n y years. We believe t h a t the more f a v o u r a b l e b a s e - h e i g h t ratio a n d the l a r g e r scale of photog r a p h y which is possible with t h e s a m e n u m b e r of p a i r s because of the g r e a t e r overlap, are all considerations which s t r e n g t h e n the tendency t o w a r d s the u s e of convergent p h o t o g r a p h y f o r c a d a s t r a l large-scale work. This point h a s been discussed in d i f f e r e n t ways. Brucklacher presented his paper in Comm. I describing the new Zeiss T w i n c a m e r a which replaced the p r e - w a r c a m e r a of Zeiss used in Switzerland by B o s s h a r d t and in the N e t h e r l a n d s by K L M and the Delft services. The convergent p h o t o g r a p h y w a s discussed in still a n o t h e r w a y in a p a p e r by George D. W h i t m o r e : "Economic f a c t o r s in the i n t e g r a t e d p h o t o g r a m m e t r i c s y s t e m of t h e U S Geological Survey." He m e n t i o n s the economic a d v a n t a g e s of t h e use of wide-angle low oblique photography, either t r a n s v e r s e or convergent. The point of discussion r e g a r d i n g the use of wide-angle for c o n v e r g e n t p h o t o g r a p h y a s w a s u s u a l in Europe before the w a r with s t a n d a r d angle, is, w h e t h e r t h e v e r y large base h e i g h t ratio of 1.23 instead of 0.63 with vertical wide-angle will not d i s t u r b the stereoscopic image. It seems t h a t the US Geological S u r v e y h a s no difficulty in this respect, because in a discussion about the role which can be played by a super wide-angle W h i t m o r e even s a y s : " a practicable u l t r a wide-angle c a m e r a would provide the m e a n s of exploiting the convergent p h o t o g r a p h y technique f u r t h e r , to obtain still l a r g e r model coverage". This m a y be t r u e in a t r a n s verse position of such a twin camera. We do not believe, however, t h a t t h i s method can be applied to convergent photography, r e s u l t i n g in a" base h e i g h t ratio which would be still l a r g e r t h a n the 1.23 with the n o r m a l wide-angle. Such t y p e of p h o t o g r a p h y would give too m a n y so-called dead spots of which no stereoscopic i m a g e can exist because objects are only visible f r o m one exposure station. We have personal experience with the Muenchen p a n o r a m a c a m e r a which in i t s stereoscopic image with n o r m a l overlap, h a s about t h e s a m e base h e i g h t ratio. Such a m u l t i t e n s vertical c a m e r a however can be used with a much l a r g e r overlap w i t h o u t d i s t u r b i n g the economy of the system. This, however, is not possible with the convergent p h o t o g r a p h y which requires exposure in such a w a y t h a t we have full overlap of each photograph. I t would be of i m p o r t a n c e to find out w h a t is the compromise between the economic considez'ations for reduction of the n u m b e r of overlaps and the quality of the stereoscopic image. It is obvious t h a t this will be d i f f e r e n t for different scales and for d i f f e r e n t types of t e r r a i n . A v e r y i n t e r e s t i n g publication is the " R a p p o r t s u r l'essai contr61~ No. 2 Verco~s. E t a b l i s s e m e n t p h o t o g r a m m ~ t r i q u e s d'une carte h l'~chelle 1 : 50.000". This report present2

14 ed by t h e P r e s i d e n t a n d b y S e c r e t a r y of C o m m . II ( P r o f . B a c h m a n n a n d Ing. H ~ b e r l i n ) i n f o r m s u s a b o u t t h e r e s u l t s of t h e p r o d u c t i o n of a r e g u l a r t o p o g r a p h i c m a p in t h e scale 1 : 50,000 of a n a r e a in F r a n c e o f abt. 170 sq.km. E a c h p a r t i c i p a t i n g service w a s allowed to u s e its o w n special m e t h o d s a n d t h e F r e n c h I G N h a s t a k e n p h o t o g r a p h s as r e q u i r e d b y t h e p a r t i c i p a t i n g services. T h e r e f o r e t h e F r e n c h I G N h a s u s e d p h o t o g r a p h s in t h e scale 1 : 50,000 w i t h SOM f i l m c a m e r a a n d a n S O M w i d e - a n g i e p l a t e c a m e r a . T h e S w i s s h a v e u s e d W i l d RC 7 p h o t o g r a p h s in t h e scale 1 : 80,000 a n d t h e I t a l i a n E I R A p h o t o g r a p h s f r o m 4000 m h e i g h t t a k e n w i t h t h e G a l i l e o - S a n t o n i T r i p l e c a m e r a o f w h i c h t h e two oblique c a m e r a s h a v e a n i n c l i n a t i o n o f 45 ° . R e s t i t u t i o n w a s c a r r i e d o u t b y t h e F r e n c h in t h e Poivilliers T y p e B a n d a second r e s t i t u t i o n in t h e P o i v i l l i e r s t y p e D. T h e B e l g i a n M i l i t a r y T o p o g r a p h i c Service u s e d t h e s a m e p h o t o g r a p h s a s t h e F r e n c h I G N a n d c a r r i e d o u t t h e r e s t i t u t i o n also in t h e P o i v i l l i e r s t y p e B. T h e S w i s s r e s t i t u t i o n w a s done in t h e W i l d A 7 a n d t h e W i l d A 8 b u t o n l y f o r One p a i r ; t h e I t a l i a n r e s t i t u t i o n in t h e Galileo S a n t o n i S t e r e o c a r t e g r a f o IV. T h e r e p o r t c o n t a i n s f u l l d e t a i l s a b o u t t i m e a n d p r e c i s i o n b u t we will i n d i c a t e o n l y t h e m o s t i m p o r t a n t f i g u r e s . T h e m e a n s q u a r e e r r o r of h e i g h t s derived f r o m c o n t o u r s in t e r r a i n s w i t h slopes of o v e r 5% is F r a n c e t y p e B 2.3 m, a n d in t y p e D 2.4 m ; f o r B e l g i u m 3.0 m ; ' f o r S w i t z e r l a n d in t h e A 8 1.5 m a n d f o r t h e I t a l i a n r e s t i t u t i o n 2.7 m. T h e m e a n s q u a r e e r r o r a f t h e o b s e r v a t i o n in h e i g h t of isolated p o i n t s in t h e s a m e s u c c e s s i o n : 1.1 m a n d 2.2 m ; 1.7 m (in t h e AT) a n d 1.7 m. A v e r y p e c u l i a r c o n s t a n t e r r o r w a s f o u n d in t h e B e l g i a n a n d S w i s s r e s t i t u t i o n b y t a k i n g t h e a v e r a g e of all e r r o r s in h e i g h t . T h e s e f i g u r e s a r e + 0 . 2 m a n d + 0 . 5 m f o r F r a n c e , - - 2 . 0 m f o r B e l g i u m , + 0 . 7 m f o r I t a l y a n d + 1 . 4 m f o r S w i t z e r l a n d in t h e AT. T h e r e p o r t e r s did n o t f i n d a n y exp l a n a t i o n f o r t h i s c o n s i d e r a b l e s y s t e m a t i c e r r o r in t h e d e t e r m i n a t i o n o f h e i g h t s . T h e o n l y p o i n t o f objection a g a i n s t t h i s v e r y v a l u a b l e r e p o r t , f o r w h i c h we a r e v e r y g r a t e f u l , lies in i t s conclusion. W e believe t h a t t h e s t a t e m e n t t h a t t h e p r e c i s i o n o f t h e c o n t o u r l i n e s i s i n d e p e n d e n t o f t h e u s e o f e i t h e r 1st o r 2 n d o r d e r i n s t r u m e n t s a n d of t h e scale o f p h o t o g r a p h y w i t h i n t h e l i m i t s of t h i s e x p e r i m e n t is n o t j u s t i f i e d . It will be n e c e s s a r y to collect m u c h m o r e m a t e r i a l b e f o r e s u c h a conclusion will be acceptable. R e g a r d i n g t h e u s e of 2 n d o r d e r i n s t r u m e n t s t h i s c a n o n l y be b a s e d on t h e r e s u l t of t h e r e s t i t u t i o n o f t h e S w i s s p h o t o g r a p h s 1 : 80,000 in t h e A 8 w h i c h is c a r r i e d o u t only f o r one p a i r . B e t w e e n t h e P o i v i l l i e r s t y p e D a n d B t h e r e is a c o n s i d e r a b l e d i f f e r e n c e , in paL-t i c u l a r in t h e m e a s u r e m e n t o f isolated points. A l t h o u g h it is in a c c o r d a n c e w i t h m y o w n e x p d r i e n c e t h a t t h e p r e c i s i o n of m e a s u r e m e n t of h e i g h t in t h e W i l d A 8 is a b o u t t h e s a m e a s in t h e W i l d A7, we do n o t believe t h a t it is j u s t i f i e d to g i v e s u c h a s t a t e m e n t in s u c h g e n e r a l t e r m s , a s done b y P r o f . B a c h m a n n . W e d r a w t h e a t t e n t i o n to t h e special p u b l i c a t i o n of E I R A w h i c h g i v e s a full descript i o n of i t s p a r t i c i p a t i o n in t h e c o n t r o l e d t e s t V e r c o r s . No. 2. O u r r e p o r t a b o u t t h i s i n t e r e s t i n g t e s t w o u l d n o t be c o m p l e t e if we did n o t m e n t i o n t h e n u m b e r o f d e t a i l s w h i c h s h o u l d be r e p r e s e n t e d on a r e g u l a r t o p o g r a p h i c m a p a n d w h i c h w e r e n o t s h o w n in t h e p r o d u c e d m a n u s c r i p t s . W e h a v e to realize, h o w e v e r , t h a t t h i s r e s t i t u t i o n is c a r r i e d o u t w i t h o u t a n y r e c o n n a i s s a n c e in a d v a n c e . B a c h m a n n s t a t e s t h a t 55% of t h e o b j e c t s w h i c h a r e e x a m i n e d in t h e field, a r e r e p r e s e n t e d v e r y correctly, 13% is m i s s i n g , a n o t h e r 13% w h i c h is indicated, should n o t be r e p r e s e n t e d a n d f o r a n o t h e r 19% d i f f e r e n t t y p e s of e r r o r s in t h e i d e n t i f i c a t i o n a r e m a d e . W e n o w come to t h e second s u b c o m m i s s i o n of C o m m . IV, w h i c h d e a l s w i t h s u r v e y s of u r b a n a r e a s . R e p o r t e r Dr. B. L. Y. D u b u i s s o n . T h i s is in f a c t t h e s a m e t y p e o f l a r g e scale w o r k a s c a r r i e d o u t f o r c a d a s t r a l p u r p o s e s , a l t h o u g h s o m e t i m e s w i t h lower requir e m e n t s f o r precision. T h e m o s t i m p o r t a n t p a r t of t h i s r e p o r t is t h e d i s c u s s i o n b e t w e e n two F r e n c h i n s t i t u t e s , e a c h a p p l y i n g t h e i r o w n special s y s t e m . T h e f i r s t is t h e service of Dr. D u b u i s s o n of t h e M i n i s t r y o f R e c o n s t r u c t i o n a n d H o u s i n g a n d t h e second of t h e F r e n c h IC-N. Dr. D u b u i s s o n a p p l i e d t h e r e c t i f y i n g m e t h o d . H e t h e r e f o r e u s e d a c a m e r a w i t h a p r i n c i p a l d i s t a n c e of 50 cm, f i l m 30 X 30 cm, w h i c h is p r o v i d e d w i t h t h r e e g y r o scopes in o r d e r to o b t a i n s u c h d a t a f o r r e c t i f i c a t i o n , t h a t h e n e e d s in t h e t e r r a i n only a

15 distance for scaling. F o r plotting it is n e c e s s a r y to use a n i n s t r u m e n t like his restitution p a n t o g r a p h in order to eliminate the displacement caused by d i f f e r e n c e s in height. The a d v a n t a g e of this method is the possibility to decentralize t h e construction of his m a p s in the various s u r v e y o r s offices a n d to m a k e u s e of p r i v a t e surveyors. The IGN of F r a n c e h a s carried out a p h o t o g r a m m e t r i c s u r v e y of a certain a r e a a p p l y i n g t h e i r n o r m a l method u s i n g the Stereotopograph Poivilliers T y p e B. This work h a s been reported in a special publication. Dr. Dubuisson s t a t e s in his conclusion t h a t the use of f i r s t - o r d e r photogrammetric e q u i p m e n t reduces t h e importance of field work w i t h o u t i n c r e a s i n g the quantity of office work. He believes however, t h a t his restitution method with its v e r y small financial i n v e s t m e n t is m o r e suitable f o r the u s e by small s u r v e y i n g organization. We believe t h i s to be a g e n e r a l problem in p h o t o g r a m m e t r y which even comes back in the article of Mr. W h i t m o r e , mentioned above, as he opposes the g e n e r a l use of w h a t he calls "the heavy i n s t r u m e n t s " for n o r m a l plotting work. In t h i s respect the F r e n c h IGN with its g r e a t q u a n t i t y of f i r s t - o r d e r i n s t r u m e n s t a k e s p e r h a p s an exceptional position.

7. Comm. V. Non-topographic applications of photogrammetry. This commission which h a s been e n t r u s t e d to I t a l y with Prof. Giovanni Boaga a s president h a s distinguished in its r e p o r t between t h e following subjects: a. b. c. d. e. f. g.

a r c h i t e c t u r e and general technique archeology a n d fine a r t s n a t u r a l sciences m i l i t a r y applications medicine a n d anthropology criminal applications other applications

2 1 9 4 9 0 3

The last column indicates the n u m b e r of p a p e r s presented to the Congress. The two papers mentioned u n d e r g. of Mr. L e m a i r e a n d H u b e n y are both of a general character, discussing the possibilities of m i c r o - s t e r e o p h o t o g r a m m e t r y . The paper of Mr. L e m a i r e deals with the precision in a l t i m e t r y and p l a n i m e t r y and the paper of Mr. H u b e n y gives t h e limitation of the possibilities of t h i s method. We believe these p a p e r s are w o r t h while to read f o r all those who s t a r t u s i n g t h i s method for the solution of v a r i o u s problems. Also a n o t h e r Belgian publication is h i g h l y i n t e r e s t i n g : C a t t e l a i n a n d V e r m e i r m a k e p r o p a g a n d a for the old idea to set u p an i n t e r n a t i o n a l photo archive of all f a m o u s buildings a n d sculptures of the civilized world. As w a s to be expected m u c h work is done in the field of electronic microscopy. FrQf. B u r k h a r d t built a special i n s t r u m e n t for this work. The s i t u a t i o n in t h i s Comm. V is expressed in a r a t h e r critical w a y in point 2 of its resolutions: one will find no new method of f u n d a m e n t a l i m p o r t a n c e in t h e received p a p e r s : some new i n s t r u m e n t s for m a k i n g p h o t o g r a p h s and f o r special p u r p o s e s are made. There is no n e w s in the realization of special r e s t i t u t i o n i n s t r u m e n t s . . . . The a u t h o r of t h e resolutions does not need a n y c o m m e n t f r o m our side, b u t we strongly s u p p o r t a f u r t h e r p a r t of h i s resolution: it would be good if every national society f o r m s a special section of wihch everybody interested in these m a t t e r s will be a member. T h a t m e a n s t h a t the kind of specialization in accordance w i t h the c h a p t e r s mentioned above will be desirable. On the other h a n d I believe t h a t only by a s y s t e m a t i c cooperation between p h o t o g r a m m e t r i s t s and v a r i o u s specialists of for i n s t a n c e medicine etc. Comm. V can become a really i m p o r t a n t commission of the ISP.

16 8. Comm. VI. Education, Terminology and Bibliography. This commission is entrusted to Austria, President Prof. Neumaier, Secretary Prof. Barvir. The most important subjects of this commission are the polyglot dictionary and the project of the bibliography. The Austrian Society of P h o t 0 g r a m m e t r y presented to the congress proof copies of its dictionary of which the text in English, French, German, Italian, Spanish, Swedish and Polish is now available. The dictionary will have for each language a special volume of about 100 pages. The contents of each volume is abt. 5000 words in alphabetical order in the language* concerned. Behind each word are columns for the 6 other languages with the numbers under which the translation in each of these languages in the other volumes can be found. One blank column makes it possible to add another language. The price of this very useful piece of work, for which the photogrammetric world is most grateful to the Austrian Society and to those gentlemen in the various countries who have assisted A u s t r i a in the translations, is r a t h e r low, viz. 2 U S dollars for each volume 1). As f a r as the bibliography is concerned it may be mentioned t h a t the proposal made by Comm. VI to e n t r u s t this p a r t to the Inter. Training Centre in Delft was accepted. The author of this article however mentioned t h a t he only could take the responsibility for this publication if the cooperation of several of the national societies can be obtained. He promised to send a circular letter to the national societies before the end of this year mentioning the financial consequences of this enterprise with some more details about the necessary cooperation. With respect to terminology no special decisions were taken. I have the impression however t h a t it would be of g r e a t advantage if at least for the main photogrammetric symbols a certain standardisation could "be obtained. We would welcome any effort of the new council to prepare proposals which could be accepted at the next International Congress. A small committee might be appointed for the preparation of proposals regarding definitions and standardization of symbols of the main features of photogrammetry. Regarding t r a i n i n g there is not much news. In the report is mentioned t h a t most of the t r a i n i n g in photogrammetry is combined either with engineering courses like in the English speaking world, or with the study for geodetic engineer like in several European countries. The only institute specialized in the use and application of air photographs to map production and in the interpretation for geological and agricultural purpose is still the Delft International Training Cent?e. Several universities find t h a t the purchase of sufficient equipment is r a t h e r expensive and f u r t h e r m o r e t h a t the time necessary for a real practical t r a i n i n g cannot be made available in most of the courses with which the study of photogrammetry is combined.

9. Comm. VII. Photographic interpretation. This commission was entrusted to the American Society of Photogrammetry which appointed Charles G. Coleman as its President an4 Earl J. Rogers as reporter. This commission, established a t the proposal of the US before the Washington Congress, had found in the American Society such an excellent representation t h a t this commission in Stockholm has again been entrusted to the USA. The report which was also published in Photogrammetric Engineering, shows the material in four major sections: General, Natural Resources Application, Engineering Application and Military Application. U n d e r par. "General" attention is paid to the photographic interpretation techniques, the equipment, personnel and training. Amongst the instruments various devices are mentioned for the determination of slopes in stereoscopic images. In particular the US Geological Survey has been active in

1) Please order this dictionary before the end of this year at the adress of Prof. Barvir, Techn. Univ. Graz, Austria.

17 this respect and we draw attention to the stereo-slope comparator of Hackman, the socalled Super-Duper-Dipper. Two papers were delivered about the t r a i n i n g of geologists in the USA. They deal, however, more with the t r a i n i n g in elementary p h o t o g r a m m e t r y for geologists t h a n with the real t r a i n i n g of geological interpretation of photographs. In accordance with the g r e a t activity in the field of photo-interpretation in t h a t country he American Society has expressed the desire to publish a Manual of PhotoInterpretation. We all would welcome such a useful textbook. We hope, however, t h a t an editorial board will be constituted which will review the contents of the book in order to avoid a certain lack of equilibrium in the t r e a t m e n t of various subjects and the kind of duplications which exist in the American Manual of Photogrammetry. A f u r t h e r wish regarding this important publication would be t h a t the editors receive such international cooperation t h a t a real international textbook published by the American Society is the result. I am fully aware however t h a t this depends mainly on the willingness of experts from abroad to answer in a positive sense the request for help from all those interested in photo-interpretation as mentioned in the report of Comm. VII on page 10. Regarding the interpretation techniques I have the impression t h a t colour photography is mentioned more frequently in this report than in 1952. Even for geology colour photographs were taken from the air and used with some success for locating lightly looking mineral deposits. Also in f o r e s t r y colour photography is used more and more, in particular for the determination of damage by insects, diseases etc. Another feature is t h a t notwithstanding the improved quality of photographic images, there is still a tendency to use r a t h e r large-scale photographs. Even in geology for which type of work the oil geologists use always photographs in the scales 1 : 4 0 , 0 0 0 - - 1 : 5 0 , 0 0 0 vertical photography of abt. 1 : 20,000 and sometimes of even larger scale are nowadays used for detailed analysis of special outcrops. This example shows t h a t the method of the early days of aerial survey to use for interpretation the same photographs made f o r instance for topographic m a p p i n g loses ground. Together with the recognition of the possibilities of photo-interpretation for d i f f e r e n t purposes and of its g r e a t economic value comes the tendency to take special photographs for each special purpose. The cost o f photography may be r a t h e r high, but the advantage of photography in a scale adapted to the special kind of i n t e r p r e t a t i o n required, will pay in m a n y cases. An example of this tendency is also the geologic m a p p i n g carried out by the US Geological Survey from high altitude photography in the scale 1 : 60,000 by means of a Kelsh Type plotter. This method combines the coverage of large areas in one stereomodel, 5 X enlargement of the original scale of photography and perfect plotting of the geological map. I cannot yet see in how f a r the combination of this high altitude flying with a 6 inch lens could be improved for interpretation purposes by the combination with transverse oblique photography with two 12 inch cameras covering the same strip of the wide-angle camera. This type of photography would give a scale which is twice as large, the base length would be half. The advantage would be the l a r g e r size of certain details. The study under a normal stereoscope of these obliques in combination with Kelsh plotting of the small-scale verticals could p e r h a p s give a very good solution for geological interpretation and geological mapping. In the f o r e s t r y section t h e r e is a remarkable p a p e r presented by H a n s Axelson regarding the effect of photo-scale on the use of aerial photographs in Swedish forestry. His conclusion, d r a w n f r o m a g r e a t number of test fields and d i f f e r e n t interpretors is, that the photography in a scale 1 : 33,000 is not appreciabl:y inferior to 1 : 16,000 f o r measurements of tree heights and estimations of various Stand f a c t o r s when enlarged pictures at 1:15,000 are utilized. This conclusion is a contradiction of the American methods as indicated on several places in litterature. We are inclined, however, to accept this Swedish statement in particular for density estimations. Whether it is true for measurement and in particular for identification of specimen, is an entirely different problem. Axelson recommends for Sweden scales not smaller t h a n 1 : 30,000 of photo2"

18 g r a p h s which should enlarged to 1:20,000. I have the impression t h a t j u s t like the author says it is not wise to conclude too much f r o m his work concerning ±he practicaI photo-scale in forestry. It would be highly interesting however, to c a r r y out research work about this important economic problem. Anotker question is the difference between the use of enlarged original photographs and the observation o f p r i n t s with stereoscopes with strong magnification, such as made by Wild now with an 8 X magnification. This commission did not p r e s e n t very much about soil survey. The report does not mention many applications of this method and only one p a p e r by Dr. J. S. Veenenbos of the Delft ITC w a s presented. I believe, however, t h a t the ITC-Buringh method, developed in Delft during recent years, is gaining ground rapidly. I t is applied nowadays already in several countries, in particular in the Middle E e a s t and in Africa. I consider this as one of the most important contributions of the Delft institute to the economic use of air photographs. 10. Decision of the Congress. Various delegate meetings and two meetings Of the General Assembly were held. We will mention only the most i m p o r t a n t decisions. The f i r s t is t h a t the Brock Award (see " P h o t o g r a m m e t r i a " Vol. XII, page 3 9 ) w a s g r a n t e d to Dr. Bertele of the Wild firm. His successive creations of the Aviotar, Aviogon and his latest. Super Aviogon have improved the quality of the raw material of the photogrammetrists and interpre= tors to such an extent t h a t we really can speak of "an outstanding and proven contribution to photograrmnetry". These optical tools put into the h a n d s of all of us and the stimulance which these lenses are for other optical designers, fully j u s t i f y the g r a n t i n g of this f i r s t Brock Award to Dr. Bertele. It does not change anything of the merits of Dr. BelC~ele however to say t h a t Dr. Richter, the creator of the Topogen lens, which is the mother of all wide-angle lenses made a f t e r 1934 also has been considered b y the Council of the I S P as a very serious candidate for the Brock Award. His death hn February 1956 required a reconsideration of the problem by the Council of the I S P which without any hesitation came to the nomination of Dr. Bertele. While dealing with a w a r d s we must mention a few honorary memberships. A few members received this honour for various reasons. Dr. Hiirry as the promotor of the use of photogrammetry in large-scale precise m a p p i n g and the application to cadastral sur')ey; General H u r a u l t as the promotor of the use of photogrammetry in small- and medium scale topographic m a p p i n g ancl as the promotor of w h a t we call the F r e n c h photogrammetric system; Prof. Dr. Cassinis as the man who is responsible for several theoretical and experimental studies which have f u r t h e r e d p h o t o g r a m m e t r y in Italy and as organizer, founder and president of the Italian photogrammetrie group; Mogenaen as the past President of the I S P and responsible for the organization of the I S P and its congress during the past four years. I like to mention specially the honorary membership granted to Prof. Dr. Bauersfeld, the creator of the Zeiss Stereoplanigraph and of m a n y elements of designs o f photogrammetric instruments. Although never taking an active part in discussions in t h e international photogrammetric world and standing in the background, it was fully justified t h a t the I S P honoured this ingenuous designer and scientist in this way because of the g r e a t influence he has had not only on the development of photogrammetry in Germany, but also f a r outside t h a t country. The most i m p o r t a n t decision w a s the acceptance of the invitation of the British Society of P h o t o g r a m m e t r y to hold the n e x t congress (in 1960) in London. The second offer was from Belgium, which it kindly w i t h d r e w in favour of England which already in 1952 invited the congress in case Sweden would not have been in a position to receive the ISP. The British Society announced the nomination of Maj. General R. L. Brown as President of the new Board. Col. R. T. L. Rogers, Director of the F a i r e y A i r Survey Ltd., as secretary-general and Mr. J. E. Odle, Director of Williamson M a n u f a c t u r i n g Co. Ltd., a s treasurer. We believe t h a t everybody can congratulate the International Society

19 with this new executive beard. The General Assembly decided to nominate the members Janicot, Reading and Schermerhorn for another four years. The Swedish Society appointed Mr. Fagerholm as new member of the council representing the outgoing executive board. There was f u r t h e r a discussion about the distribution of the various commissions. The result is as follows: Comm.

I II

France Belgium

III IV

Italy Switzerland

V VI

Germany Austria

VII

USA

More important than this was the discussion in the delegate meetings r e g a r d i n g the organization of the next Congress and the acceptance of the proposals concerned by the General Assembly. The new president, General Brown had several informal talks with the members of the council and with others. This resulted a f t e r w a r d s in a statement made during the delegates meeting. His main aim is to avoid the difficulties experienced at the present congress as described in the f i r s t p a r a g r a p h s o f this article. The president's proposal is 1. publication of a limited n u m b e r of invited papers on special subjects; 2. discussions initiated by a panel of invited persons, one of whom should be the author of the p a p e r ; 3. the marshalling, categorizing and filtering of the multitude of other papers which are presented to the congress. Around the summer of 1958 the national societies and the technical committees will be requested in a circular letter to indicate to t h e council which are the subjects which in their opinion should be thoroughly discussed a t the 1960 congress. The answers will be considered by the boards of the technical committees and by the council. In the beginning of 195.9 one of more authors will be requested to p r e p a r e a p a p e r about each accepted subject" These articles must be received before the end of 1959 in order to make it possible to publish the complete collection in a special number of " P h o t o g r a m m e t r i a " which will be simultaneous a p a r t of the new volume X I I I of the International Archives. This publication must be distributed at least four months before the congress to all those who have announced their intention to participate. Cost of this p a r t of the Archives will be included in the total costs of Vol. :~III. Regarding the publication of the national reports and of the comittee reports no special decisions were taken. In addition to these II, III and IV p a r t s of Vol. X I I I of the Archives there is still the possibility to include in p a r t V those p a p e r s presented to the congress by various authors and accepted by the Committee Boards. These papers can only be included in the Archives if the author for his own account supplies sufficient reprints. It would be highly desirable to take such measures r.egarding the committee reports that they form together p a r t III of the Archives and could be published simultaneously with part IV containing the invited papers. A s these commission reports are sometimes published in national reviews it is not very likely t h a t it will be possible to obtain r e p r i n t s of these reports already five or six months b e f o r e the congress. I have the impression t h a t with an organization as outlined here considerable improvement in the efficiency of the congress could be obtained. I believe however, t h a t the organization is in the able h a n d s of our British colleagues who have sufficient experience with this kind of work as they showed for instance in 1955 a t the British Commonwealth Survey Officers Congress in Cambridge which I had the honour to attend. The next. congress will a g a i n be d i f f e r e n t f r o m its predecessor. It will be still more difficult because of a l a r g e r number of participants and a l a r g e r scientific contribution. Notwithstanding the succes achieved in Stockholm, we all are aware t h a t the International Society of P h o t o g r a m m e t r y cannot stand still. We must develop our congresses step b y step. The outlines given by General Brown are without any doubt a contribution

20 to this future development. One of the most i m p o r t a n t items necessary for this development, however, is the cooperation of all photogrammetrists. This cooperation can be given by accepting the invitation for p r e p a r i n g papers and above all, by sending the material, ~/hatever it may be, within the time limits. It is again this delay which has given our Swedish colleagues the disappointment not to be able to attain the aims put f o r w a r d in 1952. Let us hope t h a t our British colleagues will have a better cooperation from all of u s t h a n we have given our Swedish colleagues.

Technical Resolutions adopted by the General Assembly at the V I I I Inte~national Congress for Photograznmetry in Stockholm Juli 26th 1956.

Commission I (E).

] !

1. Commission I recommends t h a t the Washington d r a f t s t a n d a r d on test methods be amended to take into account the comments received before and during the Congress. A revised d r a f t should be submitted by the Commission Board to the various National Societies for comment and published in Photogrammetria. 2. Commission I considers t h a t closer cooperation between established camera testing laboratories is desirable. Exchange of information on the techniques of testing camera and exchange of air cameras are recommended. 3. In order to ensure continuity of work between Congresses and to meet Maj. General Brown's suggestions, Commission I desires t h a t the National Reporters to the Commission be appointed as soon as possible, be individuals whose attendance at the next Congress is probable and be experienced in the work of the Commission, as defined by resolution 2. 4. Commission I expresses the wish t h a t for the future, the time-table be so a r r a n g e d as to allow the members of the Congress to visit more thoroughly the exhibition and to allow the exhibitors' s t a f f s to attend a p a r t of the Congress sessions without increasing the exhibitors' burdens. 5. Commission I expresses the wish that, because of good results obtained so far, tests on registration of the horizon be extended to some other countries.

Commission I (F). 1. La Commission I recommande que le projet de norme de Washington sur les m~thodes d'essai soit modifi~ pour tenir compte des suggestions revues avant et pendant le Congr~s. Un projet r~vis~ sera soumis p a r le Bureau de la Commission aux diverses Soci~t~s Nationales pour avis a v a n t d'etre publi~ dans Photogrammetria. 2. La Commission I estime qu'il est tr~s d~sirable d'~tablir une collaboration plus 4troite entre laboratoires de eontrole bien equip4s. Elle recommande les 4changes de documents sur les techniques de controle raises en oeuvre et les ~changes de chambres de prise de r u e s a4riennes. 3. Afin d'assurer la continuit4 du tra:~ail entre les Congr~s et d'aller au devant des suggestions du Major G~n~ral Brown, la Commission I d~sire que les r a p p o r t e u r s nationaux ~ la Commission soient design,s d~s que possible, soient des personalit~s qui assisteront probablement au prochain Congr~s et qui connaissent bien les techniques concernant le travail que la Commission se propose de promouvoir, tel qu'il est d~fini dans la r~solution No. 2. 4. La Commission I exprime le d~sir qu'~ l'avenir, l'emploi du temps soit conqu de telle mani~re que les Congressistes puissent visiter plus compl~tement l'exposition et q u e le personnel a p p a r t e n a n t aux firmes exposantes puisse assister partiellement aux

21 sessions du Congr~s, s a n s qu'il en r ~ s u l t e u n a c c r o i s s e m e n t des c h a r g e s s u p p o r t d e s p a r les e x p o s a n t s . 5. L a Commission I ~ m e t le voeu que, en r a i s o n des r ~ s u l t a t s e n c o u r a g e a n t s d~jh o b t e n u s les essais d ' e n r e g i s t r e m e n t de l'horizon soient ~ t e n d u s ~ d ' a u t r e s p a y s .

I

ommission II ( F ) .

I

1. Consid~rant le g r a n d i n t ~ r e t que p r ~ s e n t e l ' e s s a i contrSl~ No. 2 , , V e r c o r s " p o u r l'~tablissement de c a r t e s t o p o g r a p h i q u e s ~ l'~chelle de 1 : 50.000, la C o m m i s s i o n II p r o p o s e : a. que les i n s t i t u t s a y a n t p a r t i c i p ~ ~ l ' e s s a i p u b l i e n t i n t ~ g r a l e m e n t les r ~ s u l t a t s et les d o c u m e n t s q u ' i l s o n t o b t e n u s a i n s i que l'expos~ d e s m d t h o d e s et proc~d~s utilis~s b. que l'ex4cution de n o u v e a u x e s s a i s soit e n v i s a g ~ e c. que la direction de c h a q u e e s s a i de lev~ soit a s s u m ~ e p a r u n e seule c o m m i s s i o n d. que des v a r i a n t e s s o i e n t e n v i s a g ~ e s d a n s l'ex~cution des e s s a i s con{rS14s p o u r faciliter l'~tude de p r o b l ~ m e s i m p o r t a n t s t o u c h a n t a u d o m a i n e i n s t r u m e n t a l . 2. L'activit4 de la C o m m i s s i o n II doit 8tre limit~e ~ l'~tude des a p p a r e i l s et des m ~ t h o d e s de restitution. 3. E t a n t donn4 le rSle i m p o r t a n t que j o u e n t les g r a n d e s m a c h i n e s ~ calculer en g~od~sie e t en p h o t o g r a m m ~ t r i e , il e s t r e c o m m a n d ~ que la C o m m i s s i o n I I S'OCcupe d e s q u e s t i o n s s'y r a p p o r t a n t p o u r a u t a n t qu'elles t o u c h e n t d i r e c t e m e n t a u x a p p a r e i l s et m 4 t h o d e s de restitution. 4. Vu les solutions n o u v e l l e s de r e s t i t u t i o n q u ' o n p e u t encore e n v i s a g e r d a n s le d o m a i n e ~lectronique et le d o m a i n e p u r e m e n t n u m ~ r i q u e , il e s t . s o u h a i t a b t e q u e de nouve]les recherches d a n s ce d o m a i n e soient e n t r e p r i s e . 5. Vu les n o m b r e u s e s d i f f i c u l t ~ s que p r ~ s e n t e l ' a p p l i c a t i o n des m ~ t h o d e s de raise en place num~riques et m ~ c a n o - o p t i q u e s en t e r r a i n s t r ~ s a c c i d e n t , s, i l e s t d~sirable que des dtudes t h ~ o r i q u e s et p r a t i q u e s s o i e n t e n t r e p r i s e s d a n s ce d o m a i n e . 6. Vu les d i f f i c u l t ~ s c a u s ~ e s p a r le choix p l u s ou m o i n s a r b i t r a i r e du s e n s p o s i t i f des ~l~ments d ' o r i e n t a t i o n d a n s les a p p a r e i l s de r e s t i t u t i o n e x i s t a n t s , l ' a s s e m b l ~ e g~n4rale recommande : a. ~ u x c o n s t r u c t e u ~ s d ' i n s t r u m e n t s de choisir p o u r les c o n s t r u c t i o n s f u t u r e s u n syst~me de coordonn~es d~fini p a r u n t r i ~ d r e direct, son o r i g i n e se t r o u v a n t a u centre de p r o j e c t i o n et la v a l e u r de Z i n d i q u a n t la d i s t a n c e de la p r o j e c t i o n b. a u x a u t e u r s de choisir le s i g n e d e s f o ~ n u l e s en adcord a~ec ce s y s t ~ m e de p r o j e c tion et ceci i n d ~ p e n d a m m e n t des a p p a r e i l s de r e s t i t u t i o n qui s o n t ~. leur disposition c. a u x ~coles de n ' u t i l i s e r p o u r l ' e n s e i g n e m e n t que des f o r m u l e s bas~es s u r l ' i n t r o duction du s y s t ~ m e de coordonn~es propose. 7. Vu l'int~r~t que p r ~ s e n ~ e n t les ~tudes e x p ~ r i m e n t a l e s p o u r le p r o g r ~ s des m e t h o d e s et des i n s t r u m e n t s , la C o m m i s s i o n II r e c o m m a n d e q u e les t r a v a u x e x p ~ i m e n t a u x e n t r e pris p a r I ' O E E P E se d ~ v e l o p p e n t d a n s le c a d r e d ' m m c o l l a b o r a t i o n avec la SIP.

[ CommissionIII(F). [ 1. Revenant s u r la r~solution no. 1 adopt~e a u C o n g r ~ s de W a s h i n g t o n , t a C o m m i s s i o n recommande q u ' a v a n t le p r o c h a i n Congr~s, u n colloque a u m o i n s r d u n i s s e les sp~cialistes de l'a(~rotriangulation. Le p r e s i d e n t de la C o m m i s s i o n , a p r ~ s a v o i r recueilli t o u s l e s a v i s qu'il j u g e u t i l e s fixera le lieu et la date, l ' o r d r e du j o u r et la liste d e s p e r s o n n e s invit~es. 2. En r u e d ' a u g m e n t e r le r e n d e m e n t des s~ances de t r a v a i l la C o m m i s s i o n r e c o m m a n d e que la R~solution g~n~rale no. 10 soit appliqude, p a r t i c u l i ~ r e m e n t en ce qui c o n c e r n e : a. la s~lection des c o m m u n i c a t i o n s i m p o r t a n t e s b. la publication "et la d i f f u s i o n a v a n t le C o n g r ~ s

22 c. le t r a i t e m e n t de ces communications, individuellement ou p a r groupes, p a r discussion pr~par~e, dirig~e et s a n s p r d s e n t a t i o n orale. 3. L a Commission recommande que les essais c o n t r o l , s d ' a ~ r o t r i a n g u l a t i o n soient poursuivis p e n d a n t la p~riode 1956-1960 et que le president en fixe le r~glement en s ' a i d a n t de l'exp~rience acquise et apr~s consultation des p r i n c i p a u x intdress~s. D~s ~ pr6sent, la Commission constate qu'il est gdn~ralement souhait~: a. que le caract~re p r a t i q u e donn~ ~ l'essai no. 1 soit m a i n t e n u d a n s les essais ult& rieurs b. que toute latitude soit, comme pr~c~demment laiss~e a u x p a r t i c i p a n t s d a n s le choix des m~thodes et des m o y e n s d'exdcution c. que l'obligation de t r a v a i l l e r s u r polygone ~ t r a n g e r soit supprimde d. que cet a s s o u p l i s s e m e n t du r ~ g l e m e n t air comme contre-partie un r e n f o r c e m e n t de la discipline d'ex~cution eL des possibilit~s de contrSle. D a n s ce but, que la comm u n i c a t i o n des d o c u m e n t s de t r a v a i l a u directeur de l'essai soit fr~quente et r~guli~re e. que chaque p a r t i c i p a n t f o u r n i s s e au d i r e c t e u r de l'essai u n r a p p o r t d~taill~ s u r les t r a v a u x effectu~s. 4. La Commission constate avec s a t i s f a c t i o n q u ' u n e bonne collaboration c'est ~tablie entre I ' O E E P E et la S I P d a n s le domaine de l'a~rotriangulation. Elle r e c o m m a n d e que, d a n s cet esprit de collaboration, les ~tudes exp~rimentales e n t r e p r i s e s soient a c t i v e m e n t poursuivies et ~tendues. 5. Le Commission recommande q u ' u n groupe de t r a v a i l soit constitu~ p o u r l'application la p h o t o g r a m m ~ t r i e de la s t a t i s t i q u e m a t h ~ m a t i q u e et de la th~orie des e r r e u r s . Les m e m b r e s de ce groupe seront d~sign~s p a r le Conseil. Le groupe s e r a consid~ra comme une section de la Commission III a u 9~me Congr~s. I1 a u r a la facult~ de f a i r e a u x a u t r e s commissions ou g r o u p e s de t r a v a i l de la Soci~t~ I n t e r n a t i o n a l e des r e c o m m a n dations c o n c e r n a n t les essais i n t e r n a t i o n a u x .

Commission III (E). 1. R e f e r r i n g to resolution no. 1, adopted a t the Congress of W a s h i n g t o n , the Commission recommends t h a t before the n e x t Congress, at l e a s t one m e e t i n g of specialists in aerial t r i a n g u l a t i o n will be organized. The P r e s i d e n t of the Commission, a f t e r h a v i n g collected all opinions which he t h i n k s useful, fixes place a n d time; a g e n d a and list of invited persons. 2. W i t h the purpose to increase to efficiency of the Congress meetings, the Commission i°ecommends t h a t General Resolution 10 be supported, p a r t i c u l a r l y in respect of a. the selection of i m p o r t a n t p a p e r s b. the publication and distribution before the C o n g r e s s c. the p a p e r s t r e a t e d individually or in g~'oups, by m e a n s of p r e p a r e d discussions without oral presentation. 3. The Commission r e c o m m e n d s t h a t the controlled t e s t s in the field of aerial t r i a n g ulation are continued d u r i n g t h e period 1956-1960 and t h a t the P r e s i d e n t fixes the rules, t a k i n g into account the obtained experience a f t e r consultation of t h e m o s t concerned p a r t i c i p a n t s . A t t h i s m o m e n t , the Commission e s t i m a t e s t h a t it is desirable: a. t h a t the practical c h a r a c t e r , given to t e s t no. 1, be m a i n t a i n e d in f u r t h e r tests b. t h a t every liberty will be left, a s h a s been done f o r m e r l y , to the p a r t i c i p a n t s for the choice of m e t h o d s a n d m e a n s of execution c. t h a t the obligation to work on foreign t e s t fields be cancelled d. t h a t t h i s modification h a s on t h e other h a n d as a consequence t h a t t h e rules for the execution and control of the work will be m o r e strict. F o r t h i s purpose the comm u n i c a t i o n s of w o r k i n g d o c u m e n t s to t h e Director of the t e s t s should be f r e q u e n t and regular

23 e. t h a t each p a r t i c i p a n t provides the Director of the tests with detailed report about the work t h a t h a s been executed. 4. The Commission s t a t e s with s a t i s f a c t i o n t h a t a good cooperation h a s been established between the O E E P E a n d the I S P in t h e field of aerial t r i a n g u l a t i o n . She recommends that, in this sense of collaboration the e x p e r i m e n t a l studies will be actively continued and extended. 5. There shall be a w o r k i n g g r o u p on t h e application of Statistical Science a n d T h e o r y of errors to P h o t o g r a m m e t r y . This group shall be appointed by the Council and shall be considered a section of Comm. III a t the 1960 Congress. It will be authorized to make r e c o m m e n d a t i o n s concerning i n t e r n a t i o n a l e x p e r i m e n t s to other commissions or working g r o u p s of the ISP.

i Commission IV (F). [ 1. La Commission IV c o n t i n u e r a les t r a v a u x e x p ~ r i m e n t a u x et essais contrSl~s en collaboration avec les o r g a n i s a t i o n s int~ress~es. 2. Le P r e s i d e n t de la Commission IV n o m m e r a a u s s i t S t que possible, les P r e s i d e n t s des sous-Commissions IV-l, IV-2 et IV-3. 3. Les P r e s i d e n t s des sous-Commissions p r e n d r o n t contact avec les p a r t i c i p a n t s a u s s i t 6 t que possible pour ~tablir u n p r o g r a m m e provisoire des t r a v a u x e x p 6 r i m e n t a u x et essais contrbl6s qui s e r a discut~ e n t r e e u x ~ u n e r~union sp~ciale t e n u e en E u r o p e et en Am~rique. 4. Les r a p p o r t s s u r les t r a v a u x e x p 6 r i m e n t a u x doivent 6tre termin6s et soumis p a r les participants: une ann6e a v a n t le prochain Congr~s: de cette faqon la derni~re a n n i e sera consacr6e ~ l ' a n a l y s e des r~sultats. .5. U n e conference g6n6rale de la Commission IV s e r a organis6e a u m o m e n t o p p o r t u n entre les deux Congr~s. Recommendations No. 1 .

? Il e s t recommand~ que c h a c u n des p a r t i c i p a n t s ~ l'essai contr61~ no. 2 ,,Vercors" (s'il ne l'a p a s d~j~ fait) adresse au P r e s i d e n t de la Commission IV-3 u n r a p p o r t d~taill~ eomprenant: la mSthode utilis~e et le mode d'ex~cution des t r a v a u x les temps passes a u x diverses operations les plus i m p o r t a n t e s les r ~ s u l t a t s obtenus et, s'il y a lieu, des c o m m e n t a i r e s s u r ces r ~ s u l t a t s une reproduction de la m i n u t e du lev~. Ces r a p p o r t s s e r a i e n t adress~s ~ t o u t e s les d~l~gations des p a y s a d h e r a n t ~ la S I P apr~s avoir ~t~ reproduits int~gTalement. Les conclusions d'ensemble d e v r a i e n t porter s u r tous les t r a v a u x , quelle qu'en soit l'o~rigine, et une f u s i o n serait souhaitabie entre les deux r a p p o r t s pr~sent~s a u Congr~s s u r l'essai no. 2. Recommendations No. 2. I1 est recommand~ que la Commission IV-3 comprenne les lcv4s a u x ~chelles plus petites que le 1 : 5 0 . 9 0 0 dans des experiences a u x petites ~chelles. Commission I V ( E ) . 1. Commission IV will continue e x p e r i m e n t a l work and ,,essais contrSl~s" in cooperation with interested organizations. 2. The P r e s i d e n t s of Commissions IV will n a m e as soon as possible the P r e s i d e n t s of subcommissions IV-l, IV-2 a n d IV-3. 3. The P r e s i d e n t s of subcommissions will contact the p a r t i c i p a n t s as soon as possible to

24 establish a tentative program for experimental work and ,,essais control,s" which will be discussed between them at special meetings held in Europe and America. 4. Reports on experimental work must be completed and submitted by participants one year before the next Congress so t h a t the last year may be devoted to analysis of results. 5. An interim general meeting of Commission IV should be organized at a convenient time. Recon~mendations I.

1. It is recommended t h a t each participant of the "essais control6s" no. 2 "Vercors", (if not already done) submit to the President of Commission IV-3 detailed reports including : a. method and m a n n e r of execution b. time distribution for major p a r t s of the work c. results, with comments, if any d. reproduction of the manuscript. 2. Copies of this report should be distributed to each member country of the ISP. A general report should refer to all submissions, regardless of their origin, and it would be desirable to have a general report of all experimental work, both European and non-European. Recoqn,mendation H .

It is recommended t h a t 1 : 50.000 in its program.

I

Commission IV-3 includes mapping scales smaller t h a n

ommission V (F).

1. Le nombre des m~moires pr6sent6s au VIII~me Congr~s de la SIP d~montre que, depuis 1953, l'int6ret port6 aux applications sp6clules de la photogramm6trie a augment6 dans plusieurs secteurs de la science et de la technique. I1 f a u t n6anmoins observer que les rapports envoy6s h la Pr6sidence pal' les Soci~t6s Nationales int6ress6es n'ont pas toujours ~t6, ni tr~s complete, ni tr~s originaux. Le caract~re de recherche isol6s des ~tudes et des applications sp~ciales de la photog r a m m 6 t r i e - plut6t que d'application reguli~re et g6n~ralis6s de ces proc6d6s - - a 6t6 maintenu pendant tes quatre ann6es qui se sont 6ccul6es depuis le congr~s de Washington. Quoique les applications non-topographiques de la photogramm~trie soient d6j~ tr~s nombreuses et tr~s importantes, le nombre r6duit de sp6cialistes et d'instruments et les difficult~s rencontr6es pour faire entendre aux non initi6s les avantages qu'on peut t i r e r de la Photogramm6trie, sont encore les raisons principales de la modeste diffusion de ces m6thodes dans tous les Pays, m~me les plus ~volu6s. Nous ferons noter cependant la pr6diction de Mr. McNeil, qui croit que les applications non-tepographiques de la photogramm6trie devraient souclasser clans un avenir rapproch~ les applications cartographiques. 2. On ne remarque aucune m6thode nouvelle d'importance fondamentale dans les communications recues: quelques nouveaux appareils pour la prise de vues et pour des buts sp6ciaux aient 6t6 r6alis6s, il n'y a pas de nouveaut6 dans la r6alisation d'appareils sp6ciaux de restitution; de m~me il n'y a pas encore de classification syst6matique d6taill6e des applications sp6ciales de la photogramm6trie et il f a u d r a i t que pendant les quatres prochaines ann6es, cette classification des applications sp6ciales de la photogramm6trie et il f a u d r a i t que pendant les quatres prochaines ann~es, cette classification des applications d6jh employees soit envisag6e.

25 3. Il faut favoriser au maximum les recherches et les exp4riences darts ]e domaine tr~s ~tendu des applications sp4ciales: sans doute les applications topographiques de la photogramm~trie ont - - elles absorb4 jusqu'~ present la plus grande partie des efforts; mais aujourd' hui on peut dire que la photogramm~trie topographique est assez d4veloppde pour ne plus exiger le concours de t o u s l e s photogramm~tres. On pourra donc consacrer clans l'avenir un peu plus de temps, d'~tudes et d'exp~riences aux m4thodes et aux appareils destines ~ la photogramm~trie non-topographique. Nous prions les Soci~t~s Nationales de bien vouloir inviter leurs membres ~ orienter une partie de leurs e f f o r t s dans cette voie. On recommande de recueillir la Iitt4rature existante e t celle que sera prochainement publi~e et on propose d'~tablir un concours international pour un texte de photogramm~trie non-topographique, qui soit en m6me temps th~orique et pratique clair et aussi complet que possible sur les connaissances actuelles dans ce domaine. 4. On souhaite que l'enseignement de la photogramm~trie non-topographique soit introduit dans les ~coles sup~rieures, pour les matri~res o5 ses applications peuvent contribuer au progr&s scientifique et technique (g~ologie, science du sol, g4nie civil, mddicine, m~t4orologie, science foresti~re, etc.). 5. Les recherches et les expdriences dans le domaine des applications sp4ciales de la photogramm~trie devraient trouver l'appui des Soci~t4s Nationales et des industries sp~cialis~es, surtout en vue de la formation d'archives de prises de vues des chef d'oeuvres d'architecture et des recherches prdsentant un int~ret scientifique ou artistique, comme la photogramm4trie radiographique, l'~tude de l'infiniment g r a n d (astronomie) et de l'infiniment petit (molecules), les mesures des vagues et des nuages des glaciers, des fluids en mouvement etc. 6. On dolt constater que pendant les quatre ann~es qui viennent de s'~couter, les travaux effectu~s r4v~lent un manque de coordination, m~me entre les sp4cialistes d'un m~me pays. Souvent m6me, ils ne t i e n n e n t pas compte des connaissances d~j~ acquises. I1 serait donc souhaitable de former dans chacque Soci4t~ Nationale une section sp~ciale qui r4unirait routes les personnes qui s'int~ressent ~ ces questions. Des contacts p~riodiques p e r m e t t r a i e n t de f a i r e mieux connaltre les possibilit~s et les avantages de la photogramm~trie. On peut conclure que les applications non-topographiques de la photogrammdtrie sont en constant p r o ~ s et en tirer la certitude qu'elles s'entendront et s ' a f f i r m e r o n t toujours d'avantage.

I CommissionVI (E). I 1. Since the polyglot dictionary is ready to be published, the Austrian Society of Photogrammetry is requested to s t a r t distribution on the conditions mentioned in the subscription pamphlet. 2. The Board of Commission VI is requested to charge the Intel~national Trainin~ Centre for Aerial Survey (I.T.C.) at Delft with the establishing of a bibliography of photogrammetry in cooperation with the national societies. The bibliography will be organised in accordance with the rules set forward by the new Board of Commission VI. The publication of each title and resum4e will be either in English, French or German. 3. Commission VI of the International Society of Photogrammetry shall encourage and assist schools and universities offering photogrammetric education to increase the proportion of basic sciencies, mathematics and electronic engineering in their curiccula so that photogrammetrists of the future may be better equipped to develop new methods for increasing the speed and accuracy of mapping procedure&

26

CommissionVll (E). I The work of Commission V I I d u r i n g the p a s t reporting period has been conceraed with assessing the rapid advances made by photographic i n t e r p r e t a t i o n in its m a n y fields of application. The growth of this science h a s reached a stage where the present commission reporting mechanism, and the four-year reporting period are inadequate to m a i n t a i n cognizance of the field. The resolutions proposed, therefore, at t h i s time, are designed to improve the ~ervice rendered by Commission V I I as an agency for the i n t e r n a t i o n a l exchange of information on photographic interpretation. Resolved: t h a t a report s u m m a r y i n g the activities in photographic i n t e r p r e t a t i o n on an international level be prepared annually by Commission VII, and published by the national society of the country responsible for the commission. Resolved: t h a t working-groups be set up u n d e r Commission V I I to m a i n t a i n cognizance of and report upon for example the following fields of application of photographic interpretation. Photography (availability of photo coverage, desirable photo specifications etc~). Photographic I n t e r p r e t a t i o n E q u i p m e n t and Techniques. I n t e r p r e t a t i o n of surface configuration, drainage, soils, geology structures. I n t e r p r e t a t i o n of vegetation. I n t e r p r e t a t i o n of urban, r u r a l and industrial structures. I n t e r p r e t a t i o n of ice. Archeology and equivalent applications. Resolved: t h a t national societies be advised of t h e increased interest in photographic interpretation, and t h a t they assist the work of Commission V I I by designating "working group reporters", and by providing technical and bibliographic information on; photographic i n t e r p r e t a t i o n for the a n n u a l reports. Re]erences : [1] W. Schevmerharn, Impressions of the 1952 W a s h i n g t o n Congress of the I n t e r n a t i o n a l Society of Photogrammet~, P h o t o g r a m m e t r i a , 1952-53, page 1-11. [2]

H . L . Oswal, Flexure of photographic plates u n d e r t h e i r own weight and some modes of support and consequent photogrammetrie errors, P h o t o g r a m m e t r i c Record, Vol. 2, Nr. 8, page 130-144.

[3]

W. Schermerhorn and K. Neumaiev, Systematische Fehler bei der Aerotriangulation, P h o t o g r a m m e t r i a , 1939, p. 160.

[4]

E . H . Thompson, Thompson W a t t s plotting machine, The Photogrammetric Record, 1954, Vol. I, No. 3. W. Scherme~horn, Das Thompson W a t t s Stereokartierger~t, P h o t o g r a m m e t r i a , 195354, Nr. 4.

[5]

W. Schermerho~n, Die Luftbildmessung in den Niederlanden und Niederl. Ost-Indien yon 1934 bis 1938, Intern. Archiv. f Photogrammetrie, Vol. VIII.

[6]

P . A . Vermeir, La t r i a n g u l a t i o n a~rienne, Bulletin de la Soci~t~ Belge de Photogramm~trie, Nr. 35, Mars 1954, l~ages 17-57.