“Scanline rendering of parametric surfaces” by Schweitzer and Cobb
Conference:
Type(s):
Title:
- Scanline rendering of parametric surfaces
Presenter(s)/Author(s):
Abstract:
A scanline algorithm is described which renders bicubic patches directly from the parametric description without producing a polygonal approximation. The algorithm is partially based on earlier work by Whitted. A primitive object, called a “curved-edge polygon”, is defined, and an algorithm for breaking down a bicubic patch into the primitive objects is described. A general surface intersection method is employed to provide a robust silhouette edge detector. Shades are computed by calculating a cubic approximation to the normal surface and performing either a cubic or a linear interpolation of the bounding edge normals across the scanline. Subdivision of parametric surfaces is used to reduce the complexity of the surfaces being rendered, providing dramatic improvement in the results of both the silhouette detector and the shading methods.
References:
1. Blinn, J. F. “Models of Light Reflection for Computer Synthesized Pictures”. In Proceedings of SIGGRAPH ’77, ACM, July 1977, pp. 192-198.
2. Blinn, J. F. Computer Display of Curved Surfaces, Ph.D. Thesis, University of Utah, Salt Lake City, Utah, December 1978. Also Tech. Report No. 1060-126, Jet Propulsion Laboratory, Pasadena, California.
3. Catmull, E. E. A Subdivision Algorithm for Computer Display of Curved Surfaces, Ph.D. Thesis, University of Utah, Salt Lake City, Utah, December 1974. Also Tech. Report No. UTEC-CSc-74-133, Department of Computer Science, University of Utah.
4. Cohen, E.; Lyche, T.; and Riesenfeld, R. F. “Discrete B-splines and Subdivision Techniques in Computer-Aided Geometric Design and Computer Graphics”, Computer Graphics and Image Processing, Vol. 14, No. 2, October 1980, pp. 87-111. Also Tech. Report No. UUCS-79-117, Department of Computer Science, University of Utah, October 1979.
5. Lane, J. M.; Carpenter, L. C.; Whitted, J. T.; and Blinn, J. F. “Scan Line Methods for Displaying Parametrically Defined Surfaces”, Communications of the ACM, Vol. 23, No. 1, January 1980, pp. 23-34.
6. Riesenfeld, R. F.; Cohen, E.; Fish, R. D.; Thomas, S. W.; Cobb, E. S.; Barsky, B. A.; Schweitzer, D. L.; and Lane, J. M. “Using the Oslo Algorithm as a Basis for CAD/CAM Geometric Modelling”. In NCGA ’81 Conference Proceedings, National Computer Graphics Association, Inc., June 1981, pp. 345-356.