LOW COST CAVE SIMPLIFIED SYSTEM

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1 LOW COST CAVE SIMPLIFIED SYSTEM C. Quintero 1, W.J. Sarmiento 1, 2, E.L. Sierra-Ballén 1, 2 1 Grupo de Investigación en Multimedia Facultad de Ingeniería Programa ingeniería en multimedia Universidad Militar Nueva Granada Carrera 11 # , Bogotá, Colombia {u , wjaviers, elsierra, gim}@umng.edu.co 2 Departamento de Ingeniería de Sistemas Facultad de Ingeniería Universidad Nacional de Colombia Carrera 30 # 45-03, Bogotá, Colombia {wjsarmientom, elsierrab}@unal.edu.co Abstract. This paper shows the construction of a low cost advanced visualization laboratory at a Latinamerican university based on the CAVE system. The 3D stereographic design views volumes via a simplified cave immersion system of two walls placed at a 90 degree angle. To validate the system a set of 3D stereographic animations was built and shown to people. All of them believed that the device offered a good immersion experience. Keywords: CAVE, Virtual Reality, Immersion systems, low cost 1. Introduction Virtual reality (VR) is based on different immersion technologies. For example, shutter glasses, head mounted displays (HDM), and data gloves bring simple immersion experiences. To extend immersion sensations to a real world and enable the shared environments, projects such as the ImmersaDesk, visualization walls and the Cave Automatic Virtual Environment (CAVE) have been developed. The CAVE introduced at the Electronic Visualization Lab in 1992 is the top of immersion devices [1],[2]. In the CAVE a scene is built over walls in a room through independent projections at different angles. It includes also a surround audio system and stereoscopic visualization allowing the user an immersion experience in a virtual environment [1],[2]. This was initially proposed by DeFanti & Sandinen, as a cubic room with a side between 7 and 10ft long but with only three screens, frontal and laterals, and the floor. The projections were magnified by an optical system with curved mirrors. Mirrors had two purposes to decrease the physical space without reducing the projection size and to allow the projection in difficult angles, such as floor or ceiling. Raster position system is provided by the gloves and shutter glasses, allowing the user interaction. Shutter glasses split the projection in stereographic images [2]. Currently, the CAVE

2 2 C. Quintero1, W.J. Sarmiento1, 2, E.L. Sierra-Ballén1, 2 has multiple applications, such as: scientific visualization [3],[14], patient rehabilitation [5], artistic visual language [10], virtual worlds and tours [6],[7], education and training [11],[7], digital entertainment and video games [6], [8]. Generally speaking, CAVE systems are expensive undertakings. In some cases, projects have expensive requirements as the original CAVE; in others cases, proposed modifications to simplify the system, focused in cost reductions. Some of these systems do not include raster positioning and stereographic projection; others reduce the number of walls (screens) and projectors; some make use of conventional PCs, networks, projectors and handmade fabric screens. Some examples are, CAVEUT, MiniCAVE and V-CAVE at the University of Pittsburg [7], the NAVE at Georgia Institute of Technology [13]; and X-Room at Fraunhofer Institute, Technical University of Berlin and IT Service Omikron GmbH [4]. In Latinamerican countries the access to CAVE immersive systems has been restricted due high cost. An alternative to get closer to the use of this technology is the development of devices based on local resources. This paper shows first steps to develop a low cost advanced visualization laboratory at a Latinamerican university. Section two presents the methods used to build and validate the system. Section three shows results and the last section, concludes the work with references to future trends. 2. System architecture The minimal version of the CAVE system uses only two screens, examples are the front projections, V-CAVE [9] and X-Room [4] and the back projection V-CAVE [12]. These systems employ two projectors, three computers (one server to synchronize the projection of two stations), and a network. Our system uses a two wall (screens) configuration with back projection, using a unique PC with two independent video outputs to avoid the synchronization problem, see Fig 1 (b). The CAVE simplified system in non-stereo mode requires two view volumes. These view volumes have the same perspective focal point and are complemented over the visual field. The focal point is corrected following the user position, when the system has a raster position device. However, in a system without raster position the ideal view point is fixed and should be determined. For two screens with back projection this point is located in the center of the screens and their view volumes are symmetric and oriented at 90. Using a 4/3 ratio for each screen, this fixed ideal view point requires view volumes with a horizontal aperture of 90 and a vertical aperture of 72, see Fig 1(a)(b). In stereo mode, the system needs two couples of view volumes, two volumes for each eye. The couples of view volumes are separated in proportion to the human pupil distance (DP), see Fig 1 (d) This distance was calculated using the ratio between the real screen width and the mean DP (63 mm) as DP v Wv * DP = W (1)

LOW COST CAVE SIMPLIFIED SYSTEM 3 where W is the real screen width, W v is the view volume width and DP v should be the

(a) and (b) Non-stereographic view volumes, (c) system architecture and (d) Stereographic view volumes (d) 3.

of 160 x 120cm in white translucent fabric.

3 LOW COST CAVE SIMPLIFIED SYSTEM 3 where W is the real screen width, W v is the view volume width and DP v should be the couple of view volumes distance for a good stereo immersion experience. (a) (b) (c) Fig. 1. (a) and (b) Non-stereographic view volumes, (c) system architecture and (d) Stereographic view volumes (d) 3. Prototype building and system validation The CAVE simplified prototype was built using a metallic structure with two screens of 160 x 120cm in white translucent fabric. The screen is raised so that its center is located 165cm above the floor (Latinamerican mean height). The system uses a HP Compaq DC 7600 computer with a graphic card NVIDIA G- Force 6200, with two independent outputs each plugged to a Sanyo PLC-XU73 video

4 4 C. Quintero1, W.J. Sarmiento1, 2, E.L. Sierra-Ballén1, 2 projector. The projector is placed 5 m back of each screen to cover all screen area, therefore, the physical space system requirements are 660 x 660 x 225 cm 3 (width, depth and height). Fig 2 (a) shows the prototype features. For validation, five different 3D animations were built. The set of animations include: a cube moving between screens in a white background, a loop in a natural scene, a virtual tour through a residential apartment, a composition of an artistic video, and a cubic room with chess texture in the wall and loop moving through the lateral texture. For each animation four renders were processed (two for each screen) and the wide screen anaglyph video was composed. The five 3D stereographic animations were displayed to ten persons. All people were located in the determined ideal viewpoint. All of them believed that the device offered a good immersion experience. This validation allows us to conclude that we built a low cost immersive visualization device based on a simplified version of a CAVE. Fig 2 (b) and (c) show pictures of the system showing some test 3D animations (a) (b) (c) Fig. 2. (a) Prototype, (b) 3D natural scene and (c) composition of an artistic video 5. Conclusions and perspectives The system satisfies the technical and physical requirements of Latinamerican conditions. For this system to be able to provide high immersive RV technology in latinamerica much development, research and application is required. Currently we are working to increase the number of screens. We are using vehicle simulation applications and a raster positioning system based on video tracking. References 1. Cruz-Neira, C., Sandin, D., DeFanti, T., Kenyon, R., Hart, J.: The CAVE: Audio Visual Experience Automatic Virtual Environment. Communications of the ACM. Vol. 35. (1992) Cruz-Neira, C., Sandin, D., DeFanti, T.: Surround-Screen Projection-Based Virtual Reality: The Design and Implementation of the CAVE. Proceedings of the 20th annual conference

5 LOW COST CAVE SIMPLIFIED SYSTEM 5 on Computer graphics and interactive techniques (SIGGRAPH 1993). ACM Press (1993) Hudson, R., Gunn, C., Francis, G.K., Sandin, D.J., DeFanti, T.A. Mathenautics: Using VR to Visit 3-D Manifolds Randy Hudson. In: ACM Proceedings of Symposium on Interactive 3D Graphics. ACM Press (1995) Isakovic, K., Dudziak, T., Kochy, K. X-Rooms A PC-based immersive visualization environment. In: Proceedings of the 7th International Conference on 3D Web. ACM Press (2002) Jacobson, J., Redfern, M.S., Furman, J.M., Whitney, S.L., Sparto, P.J.;, Wilson, J.B., Hodges, L.F.. Balance NAVE; A Virtual Reality Facility for Research and Rehabilitation of Balance Disorders. In: Proceedings of the ACM symposium on Virtual reality software and technology. ACM Press (2001) Jacobson, J. Configuring Multiscreen Displays With Existing Computer Equipment. In: Proceedings of Human Factors and Ergonomics Society 46th Annual Meeting (2002) 7. Jacobson, J., Lewis, M. Game Engine Virtual Reality With CaveUT. IEEE Computer, Vol. 38 (2005) Jacobson, J., Le Renard, M., Lugrin, J., Cavazza, M. The CaveUT System: Immersive Entertainment Based on a Game Engine. In: Proceedings of the 2005 ACM SIGCHI International Conference on Advances in computer entertainment technology. ACM Press (2005) Jacobson, J., Kelley, M., Ellis, S., Seethaller, L. Immersive Displays for Education Using CaveUT. In: Proceedings of World Conference on Educational Multimedia, Hypermedia and Telecommunications. AACE (2005) Keefe, D.F., Acevedo Feliz, D., Moscovich, T., Laidlaw, D.H., LaViola Jr., J.J. CavePainting: A Fully Immersive 3D Artistic Medium and Interactive Experience. In: Proceedings of the 2001 symposium on Interactive 3D graphics. ACM Press (2001) Pair, J., Piepol, D. FlatWorld: A Mixed Reality Environment for Education and Training. International Conference on Information Systems, Analysis and Synthesis (2002) 12. Sauter, P.M. VR 2 Go TM A New Method for Virtual Reality Development. ACM SIGGRAPH Computer Graphics.Vol. 37 N. 1 (2003) Seay, A., Krum, D., Hodges, L., Ribarsky, W. Simulator sickness and presence in a high FOV virtual environment. In: Virtual Reality, Proceedings. IEEE. (2001) Tufo, H.M., Fischer, P.F., Papka, M.E., Blom, K. Numerical Simulation and Immersive Visualization of Hairpin Vortices. In: Proceedings of the 1999 ACM/IEEE conference on Supercomputing. ACM Press (1999)

Realistic Visual Environment for Immersive Projection Display System

Realistic Visual Environment for Immersive Projection Display System Hasup Lee Center for Education and Research of Symbiotic, Safe and Secure System Design Keio University Yokohama, Japan hasups@sdm.keio.ac.jp