This Article 
 Bibliographic References 
 Add to: 
A Curved Ray Camera for Handling Occlusions through Continuous Multiperspective Visualization
November/December 2010 (vol. 16 no. 6)
pp. 1235-1242
Jian Cui, Purdue University
Paul Rosen, University of Utah
Voicu Popescu, Purdue University
Christoph Hoffmann, Purdue University
Most images used in visualization are computed with the planar pinhole camera. This classic camera model has important advantages such as simplicity, which enables efficient software and hardware implementations, and similarity to the human eye, which yields images familiar to the user. However, the planar pinhole camera has only a single viewpoint, which limits images to parts of the scene to which there is direct line of sight. In this paper we introduce the curved ray camera to address the single viewpoint limitation. Rays are C1-continuous curves that bend to circumvent occluders. Our camera is designed to provide a fast 3-D point projection operation, which enables interactive visualization. The camera supports both 3-D surface and volume datasets. The camera is a powerful tool that enables seamless integration of multiple perspectives for overcoming occlusions in visualization while minimizing distortions.

[1] N. Elmqvist, P. Tsigas, A Taxonomy of 3D Occlusion Management for Visualization. IEEE TVCG. Vol 14, No. 5, pp. 1095–1109, 2008.
[2] J. Kruger, J. Schneider, R, Westermann, ClearView: An interactive context preserving hotspot vis technique. IEEE TVCG, Vol 12, No. 5, pp. 941–947, 2006.
[3] M. Burns, A. Finkelstein, Adaptive cutaways for comprehensible rendering of polygonal scenes. In ACM SIGGRAPH Asia, 2008.
[4] G.W. Furnas, Generalized fisheye views. In CHI'86 Conference on Human Factors in Computer Systems, pp. 16–23, 1986.
[5] J. Lamping, R. Rao, The Hyperbolic Browser: A focus + context technique for visualizing large hierarchies. J. of Visual Languages and Computing, Vol. 7, No. 1, pp. 33–35, 1996.
[6] N. Wong, M.S.T. Carpendale, S. Greenberg, EdgeLens: An interactive method for managing edge congestion in graphs. In Proc of the IEEE Symp. on Info Vis, pp. 51–58. 2003.
[7] S. Bruckner, Groller, Exploded View for Volume Data. IEEE TVCG, Vol 12, No. 5, pp. 1077–1084, 2006.
[8] W. Li, M. Agrawala, B. Curless, D. Salesin, Automated generation of interactive 3D exploded view diagrams. ACM Trans. Graph. Vol. 27, No. 3, pp. 1–7, 2008.
[9] S. Takahashi, K. Yoshida, K. Shimada, T. Nishita, Occlusion-Free Animation of Driving Routes for Car Navigation Systems. IEEE TVCG. Vol 12, No.5, pp. 1141–1148. 2006.
[10] P. Degener, R. Schnabel, C. Schwartz, and R. Klein, Effective visualization of short routes. IEEE TVCG, Vol. 14, No. 6, pp. 1452–1458, 2008.
[11] M. Agrawala, D. Zorin, T. Munzner 2000. Artistic Multiprojection Rendering. In Proc of the EG Workshop on Rendering Techniques, pp. 125–136, 2000.
[12] A. Román, G. Garg, M. Levoy,, Interactive Design of Multi-Perspective Images for Visualizing Urban Landscapes. In Proc of Visualization '04, pp. 537–544, 2004.
[13] A. Agarwala, M. Agrawala, M. Cohen, D. Salesin, R. Szeliski, Photographing long scenes with multi-viewpoint panoramas. ACM Trans. on Graphics, Vol. 25, No. 3, pp. 853–861, 2006.
[14] P. Rademacher, G. Bishop, Multiple-center-of-projection images. In Proc of SIGGRAPH '98, pp. 199–206, 1998.
[15] D. N. Wood, A. Finkelstein, J. F. Hughes, C. E. Thayer, D. H. Salesin, Multiperspective panoramas for cel animation. In Proc of SIGGRAPH '97, pp. 243–250, 1997.
[16] J. Yu, L. McMillan, General Linear Cameras. In Proc of the European Conference on Computer Vision (ECCV), Vol. 2, pp. 14–27, 2004.
[17] C. Mei, V. Popescu, E. Sacks, The Occlusion Camera. In proc. of EG 2005, Comp Graph Forum, vol. 24, No. 3, 2005.
[18] J. Yu, L. McMillan, Modelling Reflections via Multiperspective Imaging. In Proc. of Eurographics Symposium on Rendering, 2004.
[19] E. Groller, Nonlinear ray tracing: Visualizing strange worlds. The Visual Computer, Vol. 11, No. 5, pp. 263–274, 1995.
[20] D. Weiskopf, T. Schafhitzel, T. Ertl, GPU-based nonlinear ray tracing. Computer Graphics Forum 23, 3, pp. 625–633. 2004.
[21] J. Brosz, F. Samavati, M. Sheelagh, and M. Sousa, Single camera flexible projection. In Proc of the 5th international Symposium on Non-Photorealistic Animation and Rendering, pp. 33–42, 2007.
[22] P. Coleman, K. Singh, L. Barrett, N. Sudarsanam, and C. Grimm, 3D screen-space widgets for non-linear projection. In Proc of the 3rd international Conference on Computer Graphics and interactive Techniques in Australasia and South East Asia, pp. 221–228, 2005.
[23] N. Sudarsanam, C. Grimm, and K. Singh, Non-linear perspective widgets for creating multiple-view images. In Proc. of the 6th international Symposium on Non-Photorealistic Animation and Rendering, pp. 69–77, 2008.
[24] V. Popescu, P. Rosen, N. Adamo-Villani, The Graph Camera. International Conference on Computer Graphics and Interactive Techniques, ACM SIGGRAPH Asia, 2009.
[25] Desargues Thoerem. Wikipedia. Accessed in March 2010. http://en.'_theorem.
[26] Visual Molecular Dynamics. University of Illinois at Urbana Champaign., 2010.
[27] Engine Block Volume Dataset. Stanford Univ. dataengine, 2010.
[28] United States Geological Survey., 2010.

Index Terms:
Alleviating occlusions, camera model, curved rays, multiperspective visualization, interactive visualization
Jian Cui, Paul Rosen, Voicu Popescu, Christoph Hoffmann, "A Curved Ray Camera for Handling Occlusions through Continuous Multiperspective Visualization," IEEE Transactions on Visualization and Computer Graphics, vol. 16, no. 6, pp. 1235-1242, Nov.-Dec. 2010, doi:10.1109/TVCG.2010.127
Usage of this product signifies your acceptance of the Terms of Use.