“Silhouette clipping” by Sander, Gu, Gortler, Hoppe and Snyder

Approximating detailed with coarse, texture-mapped meshes results in polygonal silhouettes. To eliminate this artifact, we introduce silhouette clipping, a framework for efficiently clipping the rendering of coarse geometry to the exact silhouette of the original model. The coarse mesh is obtained using progressive hulls, a novel representation with the nesting property required for proper clipping. We describe an improved technique for constructing texture and normal maps over this coarse mesh. Given a perspective view, silhouettes are efficiently extracted from the original mesh using a precomputed search tree. Within the tree, hierarchical culling is achieved using pairs of anchored cones. The extracted silhouette edges are used to set the hardware stencil buffer and alpha buffer, which in turn clip and antialias the rendered coarse geometry. Results demonstrate that silhouette clipping can produce renderings of similar quality to high-resolution meshes in less rendering time.

1. BLYTHE, D., GRANTHAM, B., NELSON, S., AND MCREYNOLDS, T. Advanced graphics programming techniques using OpenGL. avail from www.opengl.org.
2. CIGNONI, P., MONTANI, C., ROCCHINI, C., AND SCOPIGNO, R. A general method for preserving attribute values on simplified meshes. In Visualization ’98 Proceedings, IEEE, pp. 59-66.
3. COHEN, J., OLANO, M., AND MANOCHA, D. Appearancepreserving simplification. SIGGRAPH ’98, 115-122.
4. DOBKIN, D. P., AND KIRKPATRICK, D. Determining the separation ofpreprocessed polyhedra – a unified approach. ICALP-90, LNCS 443 (1990), 4OO-413.
5. GILBERT, E. G., JOHNSON, D., AND KEERTHI, S. A Fast Procedure for Computing the Distance Between Complex Objects in Three- Dimensional Space. IEEE Journal Of Robotics and Automation, 2 (April 1988), 193-203.
6. GOOCH, A., GOOCH, B., SHIRLEY, P., AND COHEN, E. A Non- Photorealistic Lighting Model for Automatic Technical Illustration. SIGGRAPH 98, 447-452.
7. GOOCH, B., SLOAN, P., GOOCH, A., SHIRLEY, P., AND RIESEN- FELD, R. Interactive Technical Illustration. ACM Symposium on Interactive 3D graphics 1999, 31-38.
8. Gu, X., GORTLER, S., HOPPE, H., MCMILLAN, L., BROWN, B., AND STONE, A. Silhouette Mapping. Technical Report TR-1-99, Department of Computer Science, Harvard University, March 1999.
9. GUiZIEC, A. Surface simplification with variable tolerance. In Proceedings of the Second International Symposium on Medical Robotics and Computer Assisted Surgery (November 1995), pp. 132-139.
10. HECKBERT, P., AND GARLAND, M. Survey of polygonal surface simplification algorithms. In Multiresolution surface modeling (SIC- GRAPH ’97 Course notes #25). ACM SIGGRAPH, 1997.
11. HOPPE, H. Progressive meshes. SIGGRAPH ’96, 99-108.
12. HOPPE, H. View-dependent refinement of progressive meshes. SIC- GRAPH ’97, 189-198.
13. JOHANNSEN, A., AND CARTER, M. B. Clustered Backface Culling. Journal of Graphics Tools 3, 1 (1998), 1-14.
14. KOENDERINK, J. J. What does the occluding contour tell us about solid shape. Perception 13 (1984), 321-330.
15. KUMAR, S., MANOCHA, D., GARRETT, W., AND LIN, M. Hierarchical Back-Face Computation. Eurographics Rendering Workshop 1996, 235-244.
16. L AURENTINI, A. The visual hull concept for silhouette based image understanding. IEEE PAM116, 2 (1994), 150-162.
17. LINDSTROM, P., AND TURK, G. Fast and memory efficient polygonal simplification. In Visualization ’98 Proceedings, IEEE, pp. 279-286.
18. LUEBKE, D., AND ERIKSON, C. View-dependent simplification of arbitrary polygonal environments. SIGGRAPH ‘9 7, 199-208.
19. MARKOSIAN, L., KOWALSKI, M., TRYCHIN, S., AND HUGUES, J. Real time non photorealistic rendering. SIGGRAPH ’97, 415-420.
20. MARUYA, M. Generating texture map from object-surface texture data. Computer Graphics Forum (Proceedings of Eurographics ’95) 14, 3 (1995), 397-405.
21. NEIDER, J., DAVIS, T., AND WOO, M. OpenGL Programming Guide, Second Edition. Addison-Wesley, 1997.
22. NEWELL, M. E., AND SEQUIN, C. The Inside Story on Self- Intersecting Polygons. Lambda 1, 2 (1980), 20-24.
23. RASKAR, R., AND COHEN, M. Image Precision Silhouette Edges. ACM Symposium on Interactive 3D Graphics 1999, 135-140.
24. ROSSIGNAC, J., AND VAN EMMERIK, M. Hidden contours on a frame-buffer. Proceedings of the 7th Workshop on Computer Graphics Hardware (1992).
25. SNYDER, J., AND LENGYEL, J. Visibility Sorting and Compositing without Splitting for Image Layer Decompositions. SIGGRAPH ’98, 219-230.
26. SoucY, M., GODIN, G., AND RIOUX, M. A texture-mapping approach for the compression of colored 3D triangulations. The Visual Computer 12 (1986), 503-514.
27. XIA, J., AND VARSHNEY, A. Dynamic view-dependent simplification for polygonal models. In Visualization ’96 Proceedings, IEEE, pp. 327-334.