- Email: [email protected]
The virtual reality demonstration centre
('¢nnput & Graphi~ Vol. 17. No. 6. pp. 627-631, 1993
0097-8493/93 $6.00 + .00 ~ 1993 Pergamon Press Lld.
Printed in Great Britain.
Virtual Reality
THE V I R T U A L REALITY D E M O N S T R A T I O N CENTRE MARTIN GOBEL Fraunhofer Institute for Computer Graphics (IGD), Wilhelminenstrasse 7, D-64283 Darmstadt, Germany and JENS NEUGEBAUER Fraunhofer Institute for Manufacturing Engineering and Automation ( IPA ), Postfach 800469, D-70504 Stuttgart, Germany Abstract--This paper describes the first European Demonstration Centre for Virtual Reality, which has been installed at four institutes for applied research in Germany. The aims of this setting and its infrastructure are presented. The various applications and industrial branches addressed by this centre are shown. Additionally, the situation of Virtual Reality is briefly explained and a taxonomy for computer graphics, including Virtual Reality is given.
2. SIMULATION, PRESENTATION AND INTERACTION, A TAXONOMY FOR VIRTUAL REALITY Virtual Reality implies techniques for an intuitive presentation and manipulation of computer internal, abstract descriptions of states and processes that reflect our physical world or describe a synthetic world. With respect to simulation, presentation, and interaction (SP-I) Virtual Reality has the highest requirements: It presumes integration and demands realtime! Realtime in this context is defined as the evaluation of the computational model in such a way to present continuity to the human perception. Realtime, for example, is obtained by an image refresh rate of at least 15 images per second for the visual presentation or by an 8 kHz sample rate for an auditive presentation. The S-P-I concept was developed for system classification in computer graphics[l]. It is based on the three essentials of the simulation, i.e., the computational model generating and controlling virtual worlds, the presentation of these worlds and the human interaction within virtual worlds. Regarded as independent from each other, these essentials are called dimensions. Not only for reasons of simplicity but also for the purpose of establishing a concrete scheme, we identify and examplify three discrete values in each dimension (Fig. 1 ).
1. INTRODUCTION Virtual Reality--the next generation in man-machine c o m m u n i c a t i o n - - n o w is being evaluated in many prototypes in different application areas. In the beginning of the 1990s, Virtual Reality was regarded as a toy more than a tool. The use of the significant Virtual Reality-peripherals, the head mounted displays and gloves, in the entertainment business has established this image. Press articles and TV contributions on "cyberspace" reported on virtual worlds as computer-generated alternatives to the real world. This created more a fascination about the new possibilities with Virtual Reality technology and supported science fiction impression more than providing information. The social impacts of Virtual Reality were discussed and criticized very intensively prior to results coming from scientific-technical research and development work. Due to that understanding of Virtual Reality by the public and to the insufficient presentation quality of early Virtual Reality systems, application areas such as architecture and C A D - - b o t h handling very complex and extremely big data sets--hesitated to interface to Virtual Reality systems. The replacement of traditional window-based interfaces by 3D interactive Virtual Reality interfaces today is regarded as a very innovative development that still bears many risks, due to the experimental status of Virtual Reality peripherals and systems and the commercial situation of some Virtual Reality suppliers. Research programs in Europe, issued by the Commission of the European Communities (CEC) or by national funding authorities, are now starting to include Virtual Reality issues. National programs begin to include Virtual Reality research in an application dependent manner. This means that the use and the effectiveness of Virtual Reality in applications such as mechanical engineering or robotics is given a higher priority than basic research in Virtual Reality.
• Simulation: The underlying computational model produces data as a result of each step in the computational process. Data is generated at different semantical levels, e.g., geometry or higher level entities like buildings, machines, and human observers/actors. Semantics may appear statically or dynamically. This means that the underlying computational model produces either (one) discrete data sets or updates its internal states continuously and generates data subsequently. For example, a radiosity light simulation computes static geometry (states), the computation of robot functions in a production environment stands for the simulation of a process at a different semantical level. 627
628
M. GOBELand J. NEUGEBAUER
dynamicsemantics static semantics geometry ! !
singlee v e n t s /
! !
r
none interactive immersive
eventsequences/ realtimee v ~
Fig. 1. The S-P-I model for the classificationin computer graphics.
• Presentation: The presentation of simulation results addresses human senses, such as the visual one in Scientific Visualization. Auditory and haptic senses have also being addressed successfully by corresponding presentation techniques. The presentation dimension is characterized by static presentations (one discrete image for example ), by event sequences (like a recorded video from static images) or by presentations in realtime. Multisensory presentations furthermore require the synchronization of visual, auditive and haptic presentation techniques but foster the degree of immersion. • Interaction: Basically, passive and interactive computer graphics is identified. Interactive systems so far include an abstract, mainly predefined and limited mode in man-machine communication. Specific interaction devices and techniques (mouse, tablet) are used to submit the user's information to the machine. Immersion allows a direct and intuitive manipulation of objects (i.e., by gestures and human body movement) and generates also direct and intuitive feedback. This is regarded as a significant step in advanced man-machine communication. Graphics standards like GKS or PHIGS are characterized by geometric data, interactive mode, and still event (static images) presentation. Systems in scientific visualization [2] are able to process static semantics, if required, in event (image) sequences[3]. Control and steering in scientific visualization would imply dynamic semantics. An interactive mode is to be found in scientific visualization, in some very few applications also an immersive mode (e.g., virtual windtunnel[4]).
Virtual Reality approaches from the other end: Virtual Reality focusses on realtime presentation and immersive interaction. The simulation and the data may exist at different levels: geometrical data for walk-through applications or dynamic, semantical models that support objects each with a particular behaviour in virtual worlds. 3. THE VR DEMONSTRATIONCENTRE The situation described before has launched the VR Demonstration Centre initiative of the Fraunhofer Gesellschafi in Germany, one of the biggest research organizations carrying out applied research with industry. The project started 1993 and will continue for a period of 5 years. The Demonstration Centre for Virtual Reality has been established in Germany at four research institutes from different application areas. Each institute participates in this overall project with a local technology and competence centre presenting VR devices, systems, and applications. The institutes involved are IAO (Institute for Industrial Engineering), IBP (Institute for Building Physics), IGD (Institute for Computer Graphics), and IPA (Institute for Manufacturing Engineering and Automation). They operate in Stuttgart and Darmstadt focussing on specific VR relevant issues like acoustical simulations (IBP), realtime computer graphics and intuitive interaction (IGD), robotics and production environments ( IPA ), and ergonomic studies (IAO) at the different locations. The aim is to create local contact points for all questions concerning Virtual Reality and to demonstrate
The Virtual Reality Demonstration Centre VR at the upper end of the SPI-taxonomy. The new technology for future man-machine interfaces is shown in various application areas on a scientifical and technical basis. Thus, especially for small and mediumsized companies, problems can be solved regarding the application of this technology for future production and process development. The local competence centres give consultancy on Virtual Reality products and their effective use and application. Training is provided, information is spread on a sound technical level, support in modeling virtual worlds is offered. The main goal is to demonstrate that Virtual Reality is the new technology in man-machine communication and to communicate the advantages and perspectives of VR. The research infrastructure available at the institutes is used more efficiently and consistently to improve prevailing conditions and to strengthen the competitiveness of the medium-size enterprises.
3.1. Perlbrmance range ~[the Demonstration Centre The following range of performance is realized by the Demonstration Centre: 1. Dispersion of available knowledge on Virtual Reality: Seminars, workshops and in-house demonstrations organized to make methods, processes, applications, and techniques of Virtual Reality available. Additionally, participation in trade fairs are regarded as one contribution to present this topic in an objective and scientifical sound manner to the public. 2. Training of personnel: Companies that are interested in this technology may have their employees trained on VR hardware and software in the centres. New interaction and operating concepts can be analyzed. 3. Presentation of systems and components: Commercial systems and own developments are presented as the current state in technology. The range from high-end systems (high performance-high quality) to less expensive components (entry level) are presented as well. 4. Consultance: Consultation in technology and market issues of VR is provided. Application builders as well as technology developers use the experience of the centre for product decisions. Especially the introduction of VR components in available applications is of great interest. 5. Testing of new VR components: Component manufacturers and system developers make use of the facilities to test and evaluate new products for applicability and usability. 6. Application prototyping: Vivid examples of application prototypes have been developed in close cooperation with end users. 4. INFRASTRUCrURE OF THE DEMONSTRATION CENTRE
The Demonstration Centre provides current Virtual Reality products, such as datagloves, stereo displays, and sound computers. The use of this technology in
629
existing systems is demonstrated by competent staff members in training and demonstration rooms. The research and development teams at the Demonstration Centre implement specific Virtual Reality solutions efficiently. The following hardware components are currently in use at the institutes involved: • machines for numerical computations like Convex C3220, Hewlett Packard; • massive parallel machines for realtime simulations; • advanced graphics workstations, e.g., SGI single and dual headed VGX, VGXT and RE; • multimedia workstations: NEXT, SUN, SGI, Apple: • gloves like the DataGlove (VPL) and the CyberGlove (Virtex)• stereo displays: EyePhone (V PL), Crystal Eyes (Stereographics), Flight Helmet ( Virtual Research ); • stereo screen projections; • tracker: 3Space, FASTRAK (Polhemus); • audio-equipment: Convoltron (Crystal River Eng.), 3D-Audio ( Focal Point), Midi Sampler (AK AI ): • industrial robots: St~iubli: • further input devices like 6D-track balls, flying joysticks, etc.
4.1. Soliware inl?astructure and system deveh~pments At the software side, the centre accesses: • commercial Virtual Reality systems (VPL, Division, Sense8 ); • commercial systems for modelling, simulation and visualization, like TDI Explore, Prisms, AutoCAD, Catia, Bravo4, GeoMod; • institutional developments, such as planning tools, control systems, sound partical simulation programm, high-speed rendering systems and basic Virtual Reality environments. The local competence and technology centres are either using commercially available Virtual Reality systems like the early one from VPL or dVS ® from Division Ltd or WTK ® from Sense8[5] or have developed their own efficient solutions like VIRTUAL DESIGN [6 ], GIVEN [ 7 ] or VR4Robots [ 8 ]. System components such as renderers for visual and acoustical presentations, libraries to connect Virtual Reality peripherals, or interaction, navigation, and guesture recognition tools have been developed. In visual rendering, high performance graphics workstations are applied and efforts towards "realtime radiosity'" are undertaken. In acoustical rendering and simulation work concentrates on the physical simulation in room acoustics[9, 10]. The integration of acoustical and visual rendering, i.e., the definition of appropriate object attributes and the synchroneous display and replay of visual and acoustical effects with regard to realtime is reported in [11]. Guesture recognition libraries using neural networks are developed and evaluated [ 12 ]. Thus, the Demonstration Centre provides the link between manufacturers of VR components, system developers and systems, and the end user in a particular application.
630
M. GOBELand J. NEUGEBAUER
5. APPLICATION EXAMPLES Compared to the limited activities in hardware developments and some few systems under development, the main emphasis in Virtual Reality is related to the evaluation of this new technology in various applications. Using any of the platforms described above, the centre has applied Virtual Reality to applications like • • • • • • •
robotics and telepresence; architecture; CAD; medical diagnosis and training; ergonomics in product design; entertainment; media and arts.
Today, in many applications that use advanced computer graphics techniques, high quality images are evident. This is the reason architects and designers were not convinced at all in Virtual Reality at the beginning. The situation has changed significantly since some advanced system prototypes can process virtual worlds with a complexity of more than 20,000 radiosity illuminated polygons and a frame rate of about 10 frames per second. This significant step from "fruit boxes" to furniture has invoked a big commercial interest now in Virtual Reality [13 ]. From the industrial point of view, the immediate interest is in the use of Virtual Reality as a high-end presentation tool, either for product marketing or for the evaluation of complex 3D constructions. In median term, say 2-3 years, education and training systems will be developed that take advantage of Virtual Reality techniques. Not only flight simulation, but also the simulation of assembly and disassembly processes derived directly from CAD data will offer Virtual Reality as the new interface.
5.1. Fle~:ible production automation Much work is done at the research level in robotics and telepresence. The flexible production automation is of special significance to producing enterprises. Increasing use of industrial robots and automated plants are one main trend. In order to analyse the usability and the advantages of Virtual Reality in the field of industrial robots, Virtual Reality techniques were applied with commercial hard and software components. As it turned out, the package couldn't realize the requirements in the field of automation, consequently, the development of Virtual Reality components were initiated, which led to the completion of a Virtual Reality workstation that consists of an operating station and a real industrial robot[14]. By means of this workstation the operator can act in the virtual world. Head and hand movements are registered and included in the simulation. Computer generated images are directly controlled by the operator's head movements. By means of a 6D-trackball the operator can move about in the virtual world without the necessity to leave his real place. Via dataglove the operator's hand movements are directly converted into path data for a virtual robot. Thus any complicated
path in all 6 DOF can be generated in real-time. Conventional teachpanels and extensive path programming of the robot are redundant. The range of application for the system covers the field of application planning of industrial robot workcells, off-line programming of industrial robots, and teleoperation of robots [ 15 ].
5.2. CAD mechanics and rapid prototyping Currently, the first professional CAD systems for mechanics are interfacing to Virtual Reality, like Applicon's BRAVO4. The primary aim is to offer an advanced post processor that can walk through design results, inspect, and evaluate the design in 3D by stereoscopic means. The adaption to Virtual Reality systems is initiated and demonstrated in the demonstration centres, although many of these CAD packages are of US origin. The advantage of a Virtual Reality interface in CAD is obvious: as an example, pipeline construction in ship building is a tremendous task when carried out in 2D by using a 3D CAD package. Visual evaluation of correctness is even worse when performed by still frame rendering. In ship building, a specific prototyping workshop produces a large number of physical models (prototypes from wood or plastics) for the evaluation of construction and design. Virtual prototyping, i.e., applying Virtual Reality in construction and integrating functional simulations will save resources and costs in future. A further advantage is that very complex constructions and functions may be presented more easily and understandably to potential customers. The considerations are even going further: Not only presentation, but also training systems derived directly from the CAD package are under evaluation. The basic idea is to offer training once the construction is completed using CAD data. Assembly/disassembly or the exchange of parts (of an engine for example) can be virtually trained without much extra effort (for developing training components).
6. CONCLUSIONS Research and development work within the VR Demonstration Centre has been presented. Many application areas are going to install virtual environments as a testbed for the particular application. The first commercial training simulators based on VR are already under development. During the last 2 years, Virtual Reality has done a significant step forward with respect to its acceptance as the man-machine interface of the future.
Acknowledgement--We gratefully acknowledge the support of the Fraunhofer Gesellschaft in establishingVirtual Reality as a key research direction in Europe. REFERENCES
1. J. L. Encarnaq~o, P. Astheimer, W. Felger, T. Frilhauf, M. G6bel, and S. Miiller,Graphics and visualization:The essential features for the classificationof systems. Proc. ICCG. Bombay ( 1993).
The Virtual Reality Demonstration Centre 2. J. L. Encarna¢~o, et al., Graphics modeling as a basic tool for scientific visualization. Proc. 1F1P TC5/WG5.10
1~"orking Con/i'renc'e on Modeling in Computer Graphics. 3.
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8. 9.
Tokyo, Japan, Springer-Verlag, Berlin (April 1991). P. Astheimer, J. L. Encarnaqao, W. Felger, M. Friihauf, M. Grbel, and K. Karlsson, Interactive modeling in highperformance scientific visualization: The VIS-A-VIS project. Comp. Industry 19, 213-225 (1992). S. Bryson, Implementation ~?/hnmer~ive 17rtual Environments. Course notes, Siggraph ( 1992 ). W. Bauer, H.-J. Bullinger, and O. Riedel, Virtual reality as a tool for office design. Proceedings IICI, Orlando, FL (1993). P. Astheimer, W. Felger, and S. Mtiller, Virtual design: A generic VR system lbr industrial applications. Comp. & Graph. 17, 671-677 (1993). K. Brhm and W. Htibner, Virtual reality: A new user lnterfaceParadigm for industrial applications. Proceedings lmagina 93, Monte Carlo (February 1993). J. Neugebauer, Virtual Reality applied to industrial robots. Proceeding~ hnagina 93, Monte Carlo ( February t 993 ). U. Stepenson, Fortschritte bei der Computersimulation
10.
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14.
15.
631
von Schalleldern, Proceedings I'R 93, Stuttgart (February, 1993). J. Shi, A. Zhang, J. L. Encarna¢;:~o, and M. GObel, A modified radiosity algorithm for integrated visual and auditory rendering. Comp. & Graph. 17, 633-642 (1993). P. Astheimer. Realtime sonification to enhance the human-computer-interaction in virtual worlds. Proc'eeding.~ 4th Euro~raphic'~ 1t "~)rkshop on I "isuali:alion in ScienH/ic ('ot~Tpltting. Abingdon ( April 1993 ). K. Vaan~inen and K. B6hm, Gesture driven interaction as a human factor in virtual environments--An approach with neural networks. In lirlual Reality ~lwlems, R. Earnshaw (Ed.), Academic Press, New York (1992). W. Felger, P. Astheimer, M. Grbel, and S. Miiller, Application~ itl lirlual Rea/il)', video supplement submitted to Siggraph '93. T. Flaig, Einsatz yon Transputersystemen zur Simulation und Steuerung von Industrierobotern. Proceedin,k,s IR 93. Stuttgart ( Februar 1993 ). W. Strommer and J. Neugebauer, Robot simulation with Virtual Reality. Pr~ceeding.~ ESA l~))rkshop on Simu/ator~', ESA/ESTEC, Noordwijk, Netherlands ( 1992 ).
0097-8493/93 $6.00 + .00 ~ 1993 Pergamon Press Lld.
Printed in Great Britain.
Virtual Reality
THE V I R T U A L REALITY D E M O N S T R A T I O N CENTRE MARTIN GOBEL Fraunhofer Institute for Computer Graphics (IGD), Wilhelminenstrasse 7, D-64283 Darmstadt, Germany and JENS NEUGEBAUER Fraunhofer Institute for Manufacturing Engineering and Automation ( IPA ), Postfach 800469, D-70504 Stuttgart, Germany Abstract--This paper describes the first European Demonstration Centre for Virtual Reality, which has been installed at four institutes for applied research in Germany. The aims of this setting and its infrastructure are presented. The various applications and industrial branches addressed by this centre are shown. Additionally, the situation of Virtual Reality is briefly explained and a taxonomy for computer graphics, including Virtual Reality is given.
2. SIMULATION, PRESENTATION AND INTERACTION, A TAXONOMY FOR VIRTUAL REALITY Virtual Reality implies techniques for an intuitive presentation and manipulation of computer internal, abstract descriptions of states and processes that reflect our physical world or describe a synthetic world. With respect to simulation, presentation, and interaction (SP-I) Virtual Reality has the highest requirements: It presumes integration and demands realtime! Realtime in this context is defined as the evaluation of the computational model in such a way to present continuity to the human perception. Realtime, for example, is obtained by an image refresh rate of at least 15 images per second for the visual presentation or by an 8 kHz sample rate for an auditive presentation. The S-P-I concept was developed for system classification in computer graphics[l]. It is based on the three essentials of the simulation, i.e., the computational model generating and controlling virtual worlds, the presentation of these worlds and the human interaction within virtual worlds. Regarded as independent from each other, these essentials are called dimensions. Not only for reasons of simplicity but also for the purpose of establishing a concrete scheme, we identify and examplify three discrete values in each dimension (Fig. 1 ).
1. INTRODUCTION Virtual Reality--the next generation in man-machine c o m m u n i c a t i o n - - n o w is being evaluated in many prototypes in different application areas. In the beginning of the 1990s, Virtual Reality was regarded as a toy more than a tool. The use of the significant Virtual Reality-peripherals, the head mounted displays and gloves, in the entertainment business has established this image. Press articles and TV contributions on "cyberspace" reported on virtual worlds as computer-generated alternatives to the real world. This created more a fascination about the new possibilities with Virtual Reality technology and supported science fiction impression more than providing information. The social impacts of Virtual Reality were discussed and criticized very intensively prior to results coming from scientific-technical research and development work. Due to that understanding of Virtual Reality by the public and to the insufficient presentation quality of early Virtual Reality systems, application areas such as architecture and C A D - - b o t h handling very complex and extremely big data sets--hesitated to interface to Virtual Reality systems. The replacement of traditional window-based interfaces by 3D interactive Virtual Reality interfaces today is regarded as a very innovative development that still bears many risks, due to the experimental status of Virtual Reality peripherals and systems and the commercial situation of some Virtual Reality suppliers. Research programs in Europe, issued by the Commission of the European Communities (CEC) or by national funding authorities, are now starting to include Virtual Reality issues. National programs begin to include Virtual Reality research in an application dependent manner. This means that the use and the effectiveness of Virtual Reality in applications such as mechanical engineering or robotics is given a higher priority than basic research in Virtual Reality.
• Simulation: The underlying computational model produces data as a result of each step in the computational process. Data is generated at different semantical levels, e.g., geometry or higher level entities like buildings, machines, and human observers/actors. Semantics may appear statically or dynamically. This means that the underlying computational model produces either (one) discrete data sets or updates its internal states continuously and generates data subsequently. For example, a radiosity light simulation computes static geometry (states), the computation of robot functions in a production environment stands for the simulation of a process at a different semantical level. 627
628
M. GOBELand J. NEUGEBAUER
dynamicsemantics static semantics geometry ! !
singlee v e n t s /
! !
r
none interactive immersive
eventsequences/ realtimee v ~
Fig. 1. The S-P-I model for the classificationin computer graphics.
• Presentation: The presentation of simulation results addresses human senses, such as the visual one in Scientific Visualization. Auditory and haptic senses have also being addressed successfully by corresponding presentation techniques. The presentation dimension is characterized by static presentations (one discrete image for example ), by event sequences (like a recorded video from static images) or by presentations in realtime. Multisensory presentations furthermore require the synchronization of visual, auditive and haptic presentation techniques but foster the degree of immersion. • Interaction: Basically, passive and interactive computer graphics is identified. Interactive systems so far include an abstract, mainly predefined and limited mode in man-machine communication. Specific interaction devices and techniques (mouse, tablet) are used to submit the user's information to the machine. Immersion allows a direct and intuitive manipulation of objects (i.e., by gestures and human body movement) and generates also direct and intuitive feedback. This is regarded as a significant step in advanced man-machine communication. Graphics standards like GKS or PHIGS are characterized by geometric data, interactive mode, and still event (static images) presentation. Systems in scientific visualization [2] are able to process static semantics, if required, in event (image) sequences[3]. Control and steering in scientific visualization would imply dynamic semantics. An interactive mode is to be found in scientific visualization, in some very few applications also an immersive mode (e.g., virtual windtunnel[4]).
Virtual Reality approaches from the other end: Virtual Reality focusses on realtime presentation and immersive interaction. The simulation and the data may exist at different levels: geometrical data for walk-through applications or dynamic, semantical models that support objects each with a particular behaviour in virtual worlds. 3. THE VR DEMONSTRATIONCENTRE The situation described before has launched the VR Demonstration Centre initiative of the Fraunhofer Gesellschafi in Germany, one of the biggest research organizations carrying out applied research with industry. The project started 1993 and will continue for a period of 5 years. The Demonstration Centre for Virtual Reality has been established in Germany at four research institutes from different application areas. Each institute participates in this overall project with a local technology and competence centre presenting VR devices, systems, and applications. The institutes involved are IAO (Institute for Industrial Engineering), IBP (Institute for Building Physics), IGD (Institute for Computer Graphics), and IPA (Institute for Manufacturing Engineering and Automation). They operate in Stuttgart and Darmstadt focussing on specific VR relevant issues like acoustical simulations (IBP), realtime computer graphics and intuitive interaction (IGD), robotics and production environments ( IPA ), and ergonomic studies (IAO) at the different locations. The aim is to create local contact points for all questions concerning Virtual Reality and to demonstrate
The Virtual Reality Demonstration Centre VR at the upper end of the SPI-taxonomy. The new technology for future man-machine interfaces is shown in various application areas on a scientifical and technical basis. Thus, especially for small and mediumsized companies, problems can be solved regarding the application of this technology for future production and process development. The local competence centres give consultancy on Virtual Reality products and their effective use and application. Training is provided, information is spread on a sound technical level, support in modeling virtual worlds is offered. The main goal is to demonstrate that Virtual Reality is the new technology in man-machine communication and to communicate the advantages and perspectives of VR. The research infrastructure available at the institutes is used more efficiently and consistently to improve prevailing conditions and to strengthen the competitiveness of the medium-size enterprises.
3.1. Perlbrmance range ~[the Demonstration Centre The following range of performance is realized by the Demonstration Centre: 1. Dispersion of available knowledge on Virtual Reality: Seminars, workshops and in-house demonstrations organized to make methods, processes, applications, and techniques of Virtual Reality available. Additionally, participation in trade fairs are regarded as one contribution to present this topic in an objective and scientifical sound manner to the public. 2. Training of personnel: Companies that are interested in this technology may have their employees trained on VR hardware and software in the centres. New interaction and operating concepts can be analyzed. 3. Presentation of systems and components: Commercial systems and own developments are presented as the current state in technology. The range from high-end systems (high performance-high quality) to less expensive components (entry level) are presented as well. 4. Consultance: Consultation in technology and market issues of VR is provided. Application builders as well as technology developers use the experience of the centre for product decisions. Especially the introduction of VR components in available applications is of great interest. 5. Testing of new VR components: Component manufacturers and system developers make use of the facilities to test and evaluate new products for applicability and usability. 6. Application prototyping: Vivid examples of application prototypes have been developed in close cooperation with end users. 4. INFRASTRUCrURE OF THE DEMONSTRATION CENTRE
The Demonstration Centre provides current Virtual Reality products, such as datagloves, stereo displays, and sound computers. The use of this technology in
629
existing systems is demonstrated by competent staff members in training and demonstration rooms. The research and development teams at the Demonstration Centre implement specific Virtual Reality solutions efficiently. The following hardware components are currently in use at the institutes involved: • machines for numerical computations like Convex C3220, Hewlett Packard; • massive parallel machines for realtime simulations; • advanced graphics workstations, e.g., SGI single and dual headed VGX, VGXT and RE; • multimedia workstations: NEXT, SUN, SGI, Apple: • gloves like the DataGlove (VPL) and the CyberGlove (Virtex)• stereo displays: EyePhone (V PL), Crystal Eyes (Stereographics), Flight Helmet ( Virtual Research ); • stereo screen projections; • tracker: 3Space, FASTRAK (Polhemus); • audio-equipment: Convoltron (Crystal River Eng.), 3D-Audio ( Focal Point), Midi Sampler (AK AI ): • industrial robots: St~iubli: • further input devices like 6D-track balls, flying joysticks, etc.
4.1. Soliware inl?astructure and system deveh~pments At the software side, the centre accesses: • commercial Virtual Reality systems (VPL, Division, Sense8 ); • commercial systems for modelling, simulation and visualization, like TDI Explore, Prisms, AutoCAD, Catia, Bravo4, GeoMod; • institutional developments, such as planning tools, control systems, sound partical simulation programm, high-speed rendering systems and basic Virtual Reality environments. The local competence and technology centres are either using commercially available Virtual Reality systems like the early one from VPL or dVS ® from Division Ltd or WTK ® from Sense8[5] or have developed their own efficient solutions like VIRTUAL DESIGN [6 ], GIVEN [ 7 ] or VR4Robots [ 8 ]. System components such as renderers for visual and acoustical presentations, libraries to connect Virtual Reality peripherals, or interaction, navigation, and guesture recognition tools have been developed. In visual rendering, high performance graphics workstations are applied and efforts towards "realtime radiosity'" are undertaken. In acoustical rendering and simulation work concentrates on the physical simulation in room acoustics[9, 10]. The integration of acoustical and visual rendering, i.e., the definition of appropriate object attributes and the synchroneous display and replay of visual and acoustical effects with regard to realtime is reported in [11]. Guesture recognition libraries using neural networks are developed and evaluated [ 12 ]. Thus, the Demonstration Centre provides the link between manufacturers of VR components, system developers and systems, and the end user in a particular application.
630
M. GOBELand J. NEUGEBAUER
5. APPLICATION EXAMPLES Compared to the limited activities in hardware developments and some few systems under development, the main emphasis in Virtual Reality is related to the evaluation of this new technology in various applications. Using any of the platforms described above, the centre has applied Virtual Reality to applications like • • • • • • •
robotics and telepresence; architecture; CAD; medical diagnosis and training; ergonomics in product design; entertainment; media and arts.
Today, in many applications that use advanced computer graphics techniques, high quality images are evident. This is the reason architects and designers were not convinced at all in Virtual Reality at the beginning. The situation has changed significantly since some advanced system prototypes can process virtual worlds with a complexity of more than 20,000 radiosity illuminated polygons and a frame rate of about 10 frames per second. This significant step from "fruit boxes" to furniture has invoked a big commercial interest now in Virtual Reality [13 ]. From the industrial point of view, the immediate interest is in the use of Virtual Reality as a high-end presentation tool, either for product marketing or for the evaluation of complex 3D constructions. In median term, say 2-3 years, education and training systems will be developed that take advantage of Virtual Reality techniques. Not only flight simulation, but also the simulation of assembly and disassembly processes derived directly from CAD data will offer Virtual Reality as the new interface.
5.1. Fle~:ible production automation Much work is done at the research level in robotics and telepresence. The flexible production automation is of special significance to producing enterprises. Increasing use of industrial robots and automated plants are one main trend. In order to analyse the usability and the advantages of Virtual Reality in the field of industrial robots, Virtual Reality techniques were applied with commercial hard and software components. As it turned out, the package couldn't realize the requirements in the field of automation, consequently, the development of Virtual Reality components were initiated, which led to the completion of a Virtual Reality workstation that consists of an operating station and a real industrial robot[14]. By means of this workstation the operator can act in the virtual world. Head and hand movements are registered and included in the simulation. Computer generated images are directly controlled by the operator's head movements. By means of a 6D-trackball the operator can move about in the virtual world without the necessity to leave his real place. Via dataglove the operator's hand movements are directly converted into path data for a virtual robot. Thus any complicated
path in all 6 DOF can be generated in real-time. Conventional teachpanels and extensive path programming of the robot are redundant. The range of application for the system covers the field of application planning of industrial robot workcells, off-line programming of industrial robots, and teleoperation of robots [ 15 ].
5.2. CAD mechanics and rapid prototyping Currently, the first professional CAD systems for mechanics are interfacing to Virtual Reality, like Applicon's BRAVO4. The primary aim is to offer an advanced post processor that can walk through design results, inspect, and evaluate the design in 3D by stereoscopic means. The adaption to Virtual Reality systems is initiated and demonstrated in the demonstration centres, although many of these CAD packages are of US origin. The advantage of a Virtual Reality interface in CAD is obvious: as an example, pipeline construction in ship building is a tremendous task when carried out in 2D by using a 3D CAD package. Visual evaluation of correctness is even worse when performed by still frame rendering. In ship building, a specific prototyping workshop produces a large number of physical models (prototypes from wood or plastics) for the evaluation of construction and design. Virtual prototyping, i.e., applying Virtual Reality in construction and integrating functional simulations will save resources and costs in future. A further advantage is that very complex constructions and functions may be presented more easily and understandably to potential customers. The considerations are even going further: Not only presentation, but also training systems derived directly from the CAD package are under evaluation. The basic idea is to offer training once the construction is completed using CAD data. Assembly/disassembly or the exchange of parts (of an engine for example) can be virtually trained without much extra effort (for developing training components).
6. CONCLUSIONS Research and development work within the VR Demonstration Centre has been presented. Many application areas are going to install virtual environments as a testbed for the particular application. The first commercial training simulators based on VR are already under development. During the last 2 years, Virtual Reality has done a significant step forward with respect to its acceptance as the man-machine interface of the future.
Acknowledgement--We gratefully acknowledge the support of the Fraunhofer Gesellschaft in establishingVirtual Reality as a key research direction in Europe. REFERENCES
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