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Development of the application of photogrammetry to highway design in the period 1964–1968
Photogrammetria
-
Elsevier Publishing Company, Amsterdam - Printed in The Netherlands
DEVELOPMENT OF THE APPLICATION OF PHOTOGRAMMETRY TO HIGHWAY DESIGN IN THE PERIOD 1964-1968 C.-O. T E R N R Y D
Statens Viigverk, Stockholm (Sweden) (Received August 8, 1968)
SUMMARY
The intention of this paper is to discuss experiences from the development of the application of photogrammetry during the period 1964-1968 in principle. The development in the different countries is not discussed in detail as it has been reported in different papers and at different occasions. Some of these reports are given in the reference list. Another intention of the paper is to emphasize the importance of steering the development of photogrammetry into a system, that, in an effective way, combines photogrammetry, geodesy, data processing and automatic drawing. The systems and procedure must be logical and simple in order to be accepted by the engineers. The importance of concentrating the further photogrammetric research work around the problems of systematic errors is also strongly underlined. INTRODUCTION
The application of photogrammetry to highway design on an international level is now about ten years old. The first time the application was really discussed within the I.S.P. was during the London congress in 1960. Several countries had, however, before that occasion already introduced the use of photogrammetric methods in their routines of highway design. The development of the application was from the beginning quite intensive due to the strong requirements in all countries of increasing the quality and capacity of the result of the highway design. The engineers found that air-photographs were an excellent source of terrain information at least for the preliminary design-phase. The development was also increased by the development of geodetic equipments and methods and of data processing. The construction of electronic length-measurement devices, tellurometer, geodimeter, electrotape etc., meant a very great step forward for the photogrammetric methods as the problems of control measurements were diminished. The time-consuming, and in covered terrain, complicated geodetic triangulation principles could with an acceptable result be replaced by polygon traverses as the measurements of longer lengths was facilitated. The possibilities of transforming the photogrammetric data into engineering Photogrammetria,
24 (1969) 175-181
176
C.-O. TERNRYD
data were greatly increased by the development of computers and computing systems. Also the quality of the photogrammetric data became more advanced with the possibilities of correcting for systematic errors of photographs and equipment by using data processing at the transformation. The great trouble was, however, that knowledge of the character of the systematic errors was too limited. During the period 1960-1964 the application was stabilized in several countries and different working procedures or systems were developed. There were no longer any questions on the possibilities of using photogrammetry in highway design. Instead the problems of fitting the information sources into the design procedure occupied a great deal of the development capacity. Today, the procedure of highway design all over the world is separated into three different phases, namely preliminary location survey, preliminary design and
final design. The requirements of terrain information differ between these three phases. It is easily understood that the requirements of details become stronger towards the last phase and also that in the first and second phase, a survey of the area in question is more adequate. From these points of view it is quite obvious that photogrammetry has been more utilized in location survey and in preliminary design. The requirements of accuracy in planimetry and in elevation have been quite fulfilled and the photographs themselves have afforded all necessary terrain details. In the Swedish system for example, the Balplex-model has become an excellent aid for locating different alternative centrelines, without time-consuming and expensive mapping. (BLASCHKE et al., 1965; TERNRYD, 1966). FINAL DESIGN
In the phase of final design, however, the development of the application has been more weak. This fact may be due to several reasons. One reason is that it is very difficult to fix accuracy specifications for the terrain data in the final phase. These specifications must fulfil requirements of accuracy for mass-quantities as well as for construction elements. Requirements have been published in some countries, e.g., U.S.A., but on an international level the specifications still remain unsolved. The extremely rapid growth of computers and computing systems has also meant a great step forward in rationalizing the design procedure and perhaps most of the development capacity has been devoted to that field, and therefore the remaining capacity has not been enough for activity in the field of photogrammetry. A third reason is that there still remains a large amount of research work into controlling the systematic errors of the photogrammetric process. As mentioned above, the combination of photogrammetry and data processing affords a good possibility of increasing the geometrical quality by adding corrections for systematic errors, provided that their mathemathical form is known. A great deal of the errors Photogrammetria, 24
(1969) 175-181
PHOTOGRAMMETRY APPLIED TO HIGHWAY DESIGN
177
have been investigated; better film-bases etc., have reduced the systematic errors and also the photogrammetric equipment is more stable than before. The knowledge of the systematic errors is, however, still far from acceptable. The influence of the systematic errors can quite obviously be compensated for by using a lower photographing altitude, but then the economy and the efficiency of photogrammetry will be decreased. Another problem when using photogrammetry in the final design arises from vegetation, bushes, trees etc. The photographs should be taken without leaves on the trees, but in some cases problems still arise. Therefore it might be an idea to uncover the vegetation before photography. This can, however, become somewhat complicated as the right of way area depends on the horizontal, as well as on the vertical alignment of the road, and some changes may be made due to the detailed data of the terrain in the final design. Therefore the computing systems must be so designed that photogrammetric, as well as terrestrial terrain-data, combined will be accepted as input. In other words, possibilities of completing the photogrammetric data with terrestrial data must be included. This requirement has also been met in most of the existing systems. Test works have been carried out in several countries and they have clearly shown that the quality of the photogrammetric data is fully comparable to that of terrestrial data, when the mass quantities are discussed. Within the different crosssections, the deviations between photogrammetrically measured data and terrestrial data, may become larger than the tolerances of the coordinates. Experience has shown that this depends partly on the difficulties of referring photogrammetric crosssections to the terrestrial ones and partly to the fact that the choice of points within a cross-section is essential for the shape of the whole section. The system of crosssection is, unfortunately, not a good method for describing a terrain surface, but it is so far. the principle most in use. The problem of referring photogrammetric data to thc terrain is overcome by marking the horizontal control before the photography. Therefore the discussion of extending the photogrammetric control by photogrammetric methods, aerial triangulation etc., is not only a question of accuracy but also a practical problem. Premarked control-points for the detail-photography are also used as references or supports for the staking of the centreline. As an example, may be mentioned the French system (BAusSART, 1967) and the Swedish one (BLASCHKE et al., 1965; TERNRYO, 1966). Experience has shown that if the direct reference between photogrammetric data and terrain data is not in order, trouble will arise at the construction of the road when staking out the road body and the constructor will not accept the photogrammetric data. Another problem is the connection of borings to the photogrammetrieally measured cross-sections in areas where it is necessary from the construction point of view to separate between rock and soil. Different normal road-sections are very commo,n for rock and soilcut. The computer-programs for the mass-computation Photogrammetria, 24 (1969) 175-181
178
C.-O. TERNRYD
must be so designed that the interpolation at the connection between the borings and the terrain surface is facilitated. In the reports (BLASCHKEet al., 1965; TERNRYD, 1966) the different flying heights, cameras and evaluating equipments for the different phases of highway design was discussed for the period 1960-1964. These figures are still valid, as the development of photogrammetry has not contributed to any change. This fact may further underline the need of research work for increasing the photogrammetric quality. The development of the highway designing procedure has resulted in methods that combine photogrammetry, geodesy, data processing and automatic plotting in a good way. As an example may be mentioned the system developed and utilized in France and presented by BAUSSART (1967) which gives an excellent possibility for transforming the terrain data into a form that is acceptable from a highway engineering point of view. By using this system, the engineer gets necessary information for judging the results of his alternative solutions. As another example may be mentioned the Swedish system (BLASCHKE et al., 1965 TERNRYD, 1966) which has been developed mostly along equal principles. This system allows, e.g., computations of mass disposition plan for the construction, or drawn-perspectives based upon terrain information, recorded automatically from the photographs using precision-equipment and registering devices, without touching the figures by a human hand during the whole process. DIGITAL TERRAIN MODEL
During the period 1964-1968 great attention has been given to the development of the digital terrain model. This system means that information of the terrain surface and the borings, is stored in the computer in a way that allows a direct cutting out of the road-body from the model. The result can then be presented in a conventional manner using cross-sections if required. The procedure entails measuring of characteristic breakpoints in the model, which by an interpolating system, are used for determining the shape of the surface. There exist today some different systems for digital terrain models. The development of some of the systems was discussed at an I.S.P. meeting in Paris in 1967 and short presentations of the French model (called "Semis de points"), the M.I.T.-model, the Finnish model and two Swedish models are given by DELIGNY (1967), BEASCHKE (1967), WIITA (1967), HALLM~N (1967) and NORD~N (1967, respectively. The difference between the existing models consists mainly in different principles for the choice of model points and in different way of interpolation. There is also a discussion on the required density of points for an acceptable accuracy of the interpolation. The accuracy quite obviously depends on the interpolation system and, at last, the question becomes a problem of optimization. The cost of computation must be compared with the cost of measuring. Photogrammetria, 24 (1969) 175- ! 81
179
PHOTOGRAMMETRY APPLIED TO HIGHWAY DESIGN
The development of the digital terrain model is to be regarded as a great step forward in the development of highway design. This is especially true for the design of interchanges and of highways in sidesloping and rough terrain, as the system presents an effective way for checking different alternative combinations of horizontal and vertical alignments, using the same input terrain-data. When using crosssections, new information must be measured for almost all alternatives. One must. however, keep in mind that there exist many cases, maybe the majority, where the use of the digital terrain model is of a limited interest. In many cases there are other facts than the masses that influence the choice among alternatives. The problems of aesthetics and traffic-safety are often more delicate than other ones. To master these problems it is essential that the design system includes possibilities of automatic drawing of perspectives. These drawings must include the roadbody as well as the surrounding terrain, and some of the existing systems today include this possibility, using either the digital terrain model or the cross-section system. AUTOMATIC DESIGN
Questions of developing a fully automatic system for highway design are at present being discussed in several countries. In order to build up a system where the design-parameters are programmed it will become necessary to use a digital terrain model system for procuring the terrain information. The author believes, however, that it becomes more efficient to carry on the development in steps and to therefore concentrate the efforts for the immediate future upon further developments of a system to facilitate engineering judgements by taking care of the source of information, transforming the information into a form that is acceptable from designing point of view and by computing and drawing the result of the alternative solutions that are based upon engineering experience and imagination. THE FUTURE
The introduction of the combination of photogrammetry, data processing and automatic drawing in highway design has so far attained different levels in different countries. In some countries the systems are very advanced, not only theoretically, but also in practice, while in other countries, the methods are only in their initial stage, if they exist at all. The reasons for this difference in the level of development may be many, but one true reason, however, is the lack of engineers with a combined background of photogrammetry, computation and civil engineering. Experience has clearly shown that the best results of development are obtained when the methods and systems are developed and introduced by engineers, who also know the highway problems. Experience has also shown that for the introduction of the new aids, it is essential to keep in mind that the systems must be simple and logical to be accepted as aids in a complicated process. Photogrammetria,
24 (1969) 175 18l
180
C.-O. TERNRYD
T h e d e v e l o p m e n t of systems for terrain i n f o r m a t i o n is t o d a y acceptable for the two first phases of the design, a n d therefore, further efforts can be c o n c e n t r a t e d t o w a r d s the final design phase. T h e existing systems will, u n d o u b t e d l y be m o r e a d v a n c e d in the future as the d a t a processing technique develops, p r o v i d e d that the d e v e l o p m e n t of the p h o t o g r a m m e t r i c principles is increased. T h e research w o r k for increasing the quality o[ the p h o t o g r a m m e t r i c data, by correcting for systematic errors, should be actively stimulated. T h e possibilities of introducing analytical p h o t o g r a m m e t r i c methods are facilitated by the digital terrain m o d e l a n d as these principles can be of an essential value for increasing the p h o t o g r a m m e t r i c accuracy, they should be m o r e d e v e l o p e d in the c o m i n g period. T h e international interest a n d need for utilizing p h o t o g r a m m e t r y , c o m b i n e d with other sciences in highway design is very intensive. T h e r e f o r e it w o u l d be a great u n d e r t a k i n g for the I.S.P. to assist in the i n t r o d u c t i o n of existing results in countries w h e r e the m e t h o d s are not yet utilized to a full extent and also to contribute to the further d e v e l o p m e n t t o w a r d s m o r e a d v a n c e d system principles.
REFERENCES
ADOLFSSON, B. and TERNRYD, C.-O., 1968, The use of modern methods in highway planning in Sweden during the years 1964-1968. Svensk Lantmiiteritidskr., 2: 233-240. BAUSSART, M., 1967. La photographie a6rienne dans les 6tudes d'autoroutes. B,ll. Soc. Fran~'. Photogrammetrie, 27: 20-36. BLASCHKE, W., 1966a. Problems of the practical application of photogrammetry to highway design and construction. Proc. Intern. Syrup. Photo~rammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:10 pp. BLASCHKE,W., 1966b. A summary on the introduction of photogrammetry into highway design. Proc. Intern. Syrup. Photogrammetry, Tokyo.--J. Japan Soc. Photogrammetry, 2:18 pp. BLASCHKE, W., 1967. La Mod61e digital M.I.T. Bull. Soc. Franf. Photogrammetrie, 27: 37-40. BLASCHKE,W., TERNRYD, C.-O. and ZARZYCKI,J. M., 1965. Photogrammetry and data processing in highway work. Congr. Intern. Soc. Photogrammetry; lOth, Lisbon--Arch. Photogrammetry, 15(6): 24 pp. DELIGNY, J.-L., 1967. La m6thode du "Semis de points" et les programmes frangais de calcul 61ectronique de trac6s. Bull. Soc. Franf. Photogrammetrie, 27: 61-67. Goni~t, P., 1967. Le calculation 61ectronique et le dessin automatique darts 1'61aboration des projects d'autoroutes en France. Bull. Soc. Franf. Photogrammetrie, 27: 68-74. HALLMFzN, B., 1967. La repr6sentation Nordisk A.I.B. du terrain. Bull. Soc. Franf. Photogrammetrie, 27: 57-60. KAJI, H., KAMYA, R. and NASU, M., 1966. Applicability of analytical aerial triangulation to staking out of highways. Proc. Intern. Syrup. Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:20 pp. KASPER, H., 1966a. Report on the results of the international experiment "Wiesentheid". Proc. Intern. Syrup. Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:16 pp. KASPER. H., 1966b. Photogrammetry and the digital terrain model. Proc. Intern. Syrup. Photogrammetry, Tokyo~]. Japan Soc. Photogrammetry, 2:5 pp. KASPER. H., 1967. L'essai control6 international ,,Wiesentheid". Bull. Soc. Franf. Photogrammetrie, 27: 13-19. MORITO, H. and SmMAZAKI,K., 1966. A method for route location and project design induced from combination of computer with contoured orthophoto or topo map. Proc. Intern. Syrup, Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:12 pp. NAKAMURA, H., 1966. A photogrammetric technique applied to making highway perspective Photo,~rammetria, 24 (1969) 175- l 81
PHOTOGRAMMETRY APPLIED TO HIGHWAY DESIGN
18 1
drawings. Proc. lntern. Syrup. Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:21 pp. NORDIN, H., 1967. La representation digitale du terrain. Bull. Soc. Frang. Photogrammetrie, 27: 41-43. PRYOR, W. T., 1967. Engineering acceptance of interpretation and measurements. Photogrammetric Eng., 221-230. S~e~um-, L., 1966. The application of photogramrnetry to civil engineering and industry in Czeckoslovakia. Proc. Intern. Syrup. Photogrammet13', Tokyo--). Japan Soc. Photogrammetry, 2 : 4 pp. TERNRYD, C.-O., 1966. Photogrammetry, electronic computation and automatic drawing in highway planning and design today and tomorrow. Proc. Intern. Symp. Photogrammetry, Tokyo--J. Japan Soc. Photogrummetry, 2 : 1 4 pp. WHTA, ~;., 1967. La mise au point en Finlande de la m6thodes par surfaces. Bull. Soc. Fran~:. Photogrammetrie, 27: 44-56.
Photogrammetria, 24 (1969) 175-181
-
Elsevier Publishing Company, Amsterdam - Printed in The Netherlands
DEVELOPMENT OF THE APPLICATION OF PHOTOGRAMMETRY TO HIGHWAY DESIGN IN THE PERIOD 1964-1968 C.-O. T E R N R Y D
Statens Viigverk, Stockholm (Sweden) (Received August 8, 1968)
SUMMARY
The intention of this paper is to discuss experiences from the development of the application of photogrammetry during the period 1964-1968 in principle. The development in the different countries is not discussed in detail as it has been reported in different papers and at different occasions. Some of these reports are given in the reference list. Another intention of the paper is to emphasize the importance of steering the development of photogrammetry into a system, that, in an effective way, combines photogrammetry, geodesy, data processing and automatic drawing. The systems and procedure must be logical and simple in order to be accepted by the engineers. The importance of concentrating the further photogrammetric research work around the problems of systematic errors is also strongly underlined. INTRODUCTION
The application of photogrammetry to highway design on an international level is now about ten years old. The first time the application was really discussed within the I.S.P. was during the London congress in 1960. Several countries had, however, before that occasion already introduced the use of photogrammetric methods in their routines of highway design. The development of the application was from the beginning quite intensive due to the strong requirements in all countries of increasing the quality and capacity of the result of the highway design. The engineers found that air-photographs were an excellent source of terrain information at least for the preliminary design-phase. The development was also increased by the development of geodetic equipments and methods and of data processing. The construction of electronic length-measurement devices, tellurometer, geodimeter, electrotape etc., meant a very great step forward for the photogrammetric methods as the problems of control measurements were diminished. The time-consuming, and in covered terrain, complicated geodetic triangulation principles could with an acceptable result be replaced by polygon traverses as the measurements of longer lengths was facilitated. The possibilities of transforming the photogrammetric data into engineering Photogrammetria,
24 (1969) 175-181
176
C.-O. TERNRYD
data were greatly increased by the development of computers and computing systems. Also the quality of the photogrammetric data became more advanced with the possibilities of correcting for systematic errors of photographs and equipment by using data processing at the transformation. The great trouble was, however, that knowledge of the character of the systematic errors was too limited. During the period 1960-1964 the application was stabilized in several countries and different working procedures or systems were developed. There were no longer any questions on the possibilities of using photogrammetry in highway design. Instead the problems of fitting the information sources into the design procedure occupied a great deal of the development capacity. Today, the procedure of highway design all over the world is separated into three different phases, namely preliminary location survey, preliminary design and
final design. The requirements of terrain information differ between these three phases. It is easily understood that the requirements of details become stronger towards the last phase and also that in the first and second phase, a survey of the area in question is more adequate. From these points of view it is quite obvious that photogrammetry has been more utilized in location survey and in preliminary design. The requirements of accuracy in planimetry and in elevation have been quite fulfilled and the photographs themselves have afforded all necessary terrain details. In the Swedish system for example, the Balplex-model has become an excellent aid for locating different alternative centrelines, without time-consuming and expensive mapping. (BLASCHKE et al., 1965; TERNRYD, 1966). FINAL DESIGN
In the phase of final design, however, the development of the application has been more weak. This fact may be due to several reasons. One reason is that it is very difficult to fix accuracy specifications for the terrain data in the final phase. These specifications must fulfil requirements of accuracy for mass-quantities as well as for construction elements. Requirements have been published in some countries, e.g., U.S.A., but on an international level the specifications still remain unsolved. The extremely rapid growth of computers and computing systems has also meant a great step forward in rationalizing the design procedure and perhaps most of the development capacity has been devoted to that field, and therefore the remaining capacity has not been enough for activity in the field of photogrammetry. A third reason is that there still remains a large amount of research work into controlling the systematic errors of the photogrammetric process. As mentioned above, the combination of photogrammetry and data processing affords a good possibility of increasing the geometrical quality by adding corrections for systematic errors, provided that their mathemathical form is known. A great deal of the errors Photogrammetria, 24
(1969) 175-181
PHOTOGRAMMETRY APPLIED TO HIGHWAY DESIGN
177
have been investigated; better film-bases etc., have reduced the systematic errors and also the photogrammetric equipment is more stable than before. The knowledge of the systematic errors is, however, still far from acceptable. The influence of the systematic errors can quite obviously be compensated for by using a lower photographing altitude, but then the economy and the efficiency of photogrammetry will be decreased. Another problem when using photogrammetry in the final design arises from vegetation, bushes, trees etc. The photographs should be taken without leaves on the trees, but in some cases problems still arise. Therefore it might be an idea to uncover the vegetation before photography. This can, however, become somewhat complicated as the right of way area depends on the horizontal, as well as on the vertical alignment of the road, and some changes may be made due to the detailed data of the terrain in the final design. Therefore the computing systems must be so designed that photogrammetric, as well as terrestrial terrain-data, combined will be accepted as input. In other words, possibilities of completing the photogrammetric data with terrestrial data must be included. This requirement has also been met in most of the existing systems. Test works have been carried out in several countries and they have clearly shown that the quality of the photogrammetric data is fully comparable to that of terrestrial data, when the mass quantities are discussed. Within the different crosssections, the deviations between photogrammetrically measured data and terrestrial data, may become larger than the tolerances of the coordinates. Experience has shown that this depends partly on the difficulties of referring photogrammetric crosssections to the terrestrial ones and partly to the fact that the choice of points within a cross-section is essential for the shape of the whole section. The system of crosssection is, unfortunately, not a good method for describing a terrain surface, but it is so far. the principle most in use. The problem of referring photogrammetric data to thc terrain is overcome by marking the horizontal control before the photography. Therefore the discussion of extending the photogrammetric control by photogrammetric methods, aerial triangulation etc., is not only a question of accuracy but also a practical problem. Premarked control-points for the detail-photography are also used as references or supports for the staking of the centreline. As an example, may be mentioned the French system (BAusSART, 1967) and the Swedish one (BLASCHKE et al., 1965; TERNRYO, 1966). Experience has shown that if the direct reference between photogrammetric data and terrain data is not in order, trouble will arise at the construction of the road when staking out the road body and the constructor will not accept the photogrammetric data. Another problem is the connection of borings to the photogrammetrieally measured cross-sections in areas where it is necessary from the construction point of view to separate between rock and soil. Different normal road-sections are very commo,n for rock and soilcut. The computer-programs for the mass-computation Photogrammetria, 24 (1969) 175-181
178
C.-O. TERNRYD
must be so designed that the interpolation at the connection between the borings and the terrain surface is facilitated. In the reports (BLASCHKEet al., 1965; TERNRYD, 1966) the different flying heights, cameras and evaluating equipments for the different phases of highway design was discussed for the period 1960-1964. These figures are still valid, as the development of photogrammetry has not contributed to any change. This fact may further underline the need of research work for increasing the photogrammetric quality. The development of the highway designing procedure has resulted in methods that combine photogrammetry, geodesy, data processing and automatic plotting in a good way. As an example may be mentioned the system developed and utilized in France and presented by BAUSSART (1967) which gives an excellent possibility for transforming the terrain data into a form that is acceptable from a highway engineering point of view. By using this system, the engineer gets necessary information for judging the results of his alternative solutions. As another example may be mentioned the Swedish system (BLASCHKE et al., 1965 TERNRYD, 1966) which has been developed mostly along equal principles. This system allows, e.g., computations of mass disposition plan for the construction, or drawn-perspectives based upon terrain information, recorded automatically from the photographs using precision-equipment and registering devices, without touching the figures by a human hand during the whole process. DIGITAL TERRAIN MODEL
During the period 1964-1968 great attention has been given to the development of the digital terrain model. This system means that information of the terrain surface and the borings, is stored in the computer in a way that allows a direct cutting out of the road-body from the model. The result can then be presented in a conventional manner using cross-sections if required. The procedure entails measuring of characteristic breakpoints in the model, which by an interpolating system, are used for determining the shape of the surface. There exist today some different systems for digital terrain models. The development of some of the systems was discussed at an I.S.P. meeting in Paris in 1967 and short presentations of the French model (called "Semis de points"), the M.I.T.-model, the Finnish model and two Swedish models are given by DELIGNY (1967), BEASCHKE (1967), WIITA (1967), HALLM~N (1967) and NORD~N (1967, respectively. The difference between the existing models consists mainly in different principles for the choice of model points and in different way of interpolation. There is also a discussion on the required density of points for an acceptable accuracy of the interpolation. The accuracy quite obviously depends on the interpolation system and, at last, the question becomes a problem of optimization. The cost of computation must be compared with the cost of measuring. Photogrammetria, 24 (1969) 175- ! 81
179
PHOTOGRAMMETRY APPLIED TO HIGHWAY DESIGN
The development of the digital terrain model is to be regarded as a great step forward in the development of highway design. This is especially true for the design of interchanges and of highways in sidesloping and rough terrain, as the system presents an effective way for checking different alternative combinations of horizontal and vertical alignments, using the same input terrain-data. When using crosssections, new information must be measured for almost all alternatives. One must. however, keep in mind that there exist many cases, maybe the majority, where the use of the digital terrain model is of a limited interest. In many cases there are other facts than the masses that influence the choice among alternatives. The problems of aesthetics and traffic-safety are often more delicate than other ones. To master these problems it is essential that the design system includes possibilities of automatic drawing of perspectives. These drawings must include the roadbody as well as the surrounding terrain, and some of the existing systems today include this possibility, using either the digital terrain model or the cross-section system. AUTOMATIC DESIGN
Questions of developing a fully automatic system for highway design are at present being discussed in several countries. In order to build up a system where the design-parameters are programmed it will become necessary to use a digital terrain model system for procuring the terrain information. The author believes, however, that it becomes more efficient to carry on the development in steps and to therefore concentrate the efforts for the immediate future upon further developments of a system to facilitate engineering judgements by taking care of the source of information, transforming the information into a form that is acceptable from designing point of view and by computing and drawing the result of the alternative solutions that are based upon engineering experience and imagination. THE FUTURE
The introduction of the combination of photogrammetry, data processing and automatic drawing in highway design has so far attained different levels in different countries. In some countries the systems are very advanced, not only theoretically, but also in practice, while in other countries, the methods are only in their initial stage, if they exist at all. The reasons for this difference in the level of development may be many, but one true reason, however, is the lack of engineers with a combined background of photogrammetry, computation and civil engineering. Experience has clearly shown that the best results of development are obtained when the methods and systems are developed and introduced by engineers, who also know the highway problems. Experience has also shown that for the introduction of the new aids, it is essential to keep in mind that the systems must be simple and logical to be accepted as aids in a complicated process. Photogrammetria,
24 (1969) 175 18l
180
C.-O. TERNRYD
T h e d e v e l o p m e n t of systems for terrain i n f o r m a t i o n is t o d a y acceptable for the two first phases of the design, a n d therefore, further efforts can be c o n c e n t r a t e d t o w a r d s the final design phase. T h e existing systems will, u n d o u b t e d l y be m o r e a d v a n c e d in the future as the d a t a processing technique develops, p r o v i d e d that the d e v e l o p m e n t of the p h o t o g r a m m e t r i c principles is increased. T h e research w o r k for increasing the quality o[ the p h o t o g r a m m e t r i c data, by correcting for systematic errors, should be actively stimulated. T h e possibilities of introducing analytical p h o t o g r a m m e t r i c methods are facilitated by the digital terrain m o d e l a n d as these principles can be of an essential value for increasing the p h o t o g r a m m e t r i c accuracy, they should be m o r e d e v e l o p e d in the c o m i n g period. T h e international interest a n d need for utilizing p h o t o g r a m m e t r y , c o m b i n e d with other sciences in highway design is very intensive. T h e r e f o r e it w o u l d be a great u n d e r t a k i n g for the I.S.P. to assist in the i n t r o d u c t i o n of existing results in countries w h e r e the m e t h o d s are not yet utilized to a full extent and also to contribute to the further d e v e l o p m e n t t o w a r d s m o r e a d v a n c e d system principles.
REFERENCES
ADOLFSSON, B. and TERNRYD, C.-O., 1968, The use of modern methods in highway planning in Sweden during the years 1964-1968. Svensk Lantmiiteritidskr., 2: 233-240. BAUSSART, M., 1967. La photographie a6rienne dans les 6tudes d'autoroutes. B,ll. Soc. Fran~'. Photogrammetrie, 27: 20-36. BLASCHKE, W., 1966a. Problems of the practical application of photogrammetry to highway design and construction. Proc. Intern. Syrup. Photo~rammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:10 pp. BLASCHKE,W., 1966b. A summary on the introduction of photogrammetry into highway design. Proc. Intern. Syrup. Photogrammetry, Tokyo.--J. Japan Soc. Photogrammetry, 2:18 pp. BLASCHKE, W., 1967. La Mod61e digital M.I.T. Bull. Soc. Franf. Photogrammetrie, 27: 37-40. BLASCHKE,W., TERNRYD, C.-O. and ZARZYCKI,J. M., 1965. Photogrammetry and data processing in highway work. Congr. Intern. Soc. Photogrammetry; lOth, Lisbon--Arch. Photogrammetry, 15(6): 24 pp. DELIGNY, J.-L., 1967. La m6thode du "Semis de points" et les programmes frangais de calcul 61ectronique de trac6s. Bull. Soc. Franf. Photogrammetrie, 27: 61-67. Goni~t, P., 1967. Le calculation 61ectronique et le dessin automatique darts 1'61aboration des projects d'autoroutes en France. Bull. Soc. Franf. Photogrammetrie, 27: 68-74. HALLMFzN, B., 1967. La repr6sentation Nordisk A.I.B. du terrain. Bull. Soc. Franf. Photogrammetrie, 27: 57-60. KAJI, H., KAMYA, R. and NASU, M., 1966. Applicability of analytical aerial triangulation to staking out of highways. Proc. Intern. Syrup. Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:20 pp. KASPER, H., 1966a. Report on the results of the international experiment "Wiesentheid". Proc. Intern. Syrup. Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:16 pp. KASPER. H., 1966b. Photogrammetry and the digital terrain model. Proc. Intern. Syrup. Photogrammetry, Tokyo~]. Japan Soc. Photogrammetry, 2:5 pp. KASPER. H., 1967. L'essai control6 international ,,Wiesentheid". Bull. Soc. Franf. Photogrammetrie, 27: 13-19. MORITO, H. and SmMAZAKI,K., 1966. A method for route location and project design induced from combination of computer with contoured orthophoto or topo map. Proc. Intern. Syrup, Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:12 pp. NAKAMURA, H., 1966. A photogrammetric technique applied to making highway perspective Photo,~rammetria, 24 (1969) 175- l 81
PHOTOGRAMMETRY APPLIED TO HIGHWAY DESIGN
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drawings. Proc. lntern. Syrup. Photogrammetry, Tokyo--J. Japan Soc. Photogrammetry, 2:21 pp. NORDIN, H., 1967. La representation digitale du terrain. Bull. Soc. Frang. Photogrammetrie, 27: 41-43. PRYOR, W. T., 1967. Engineering acceptance of interpretation and measurements. Photogrammetric Eng., 221-230. S~e~um-, L., 1966. The application of photogramrnetry to civil engineering and industry in Czeckoslovakia. Proc. Intern. Syrup. Photogrammet13', Tokyo--). Japan Soc. Photogrammetry, 2 : 4 pp. TERNRYD, C.-O., 1966. Photogrammetry, electronic computation and automatic drawing in highway planning and design today and tomorrow. Proc. Intern. Symp. Photogrammetry, Tokyo--J. Japan Soc. Photogrummetry, 2 : 1 4 pp. WHTA, ~;., 1967. La mise au point en Finlande de la m6thodes par surfaces. Bull. Soc. Fran~:. Photogrammetrie, 27: 44-56.
Photogrammetria, 24 (1969) 175-181