Atmospheric illumination and shadows

ABSTRACT

The shadow volume algorithm of Frank Crow was reorganized to provide information on the regions of illuminated space in front of each visible surface. This information is used to calculate the extra intensity due to atmospheric scattering, so when the atmosphere is partly in shadow, columns of scattered light will be visible. For efficiency in sorting the shadow edges, the image is computed in polar coordinates.

REFERENCES

• 1: Lance Williams, Casting curved shadows on curved surfaces, Proceedings of the 5th annual conference on Computer graphics and interactive techniques, p.270-274, August 23-25, 1978
• 2: Peter Atherton , Kevin Weiler , Donald Greenberg, Polygon shadow generation, Proceedings of the 5th annual conference on Computer graphics and interactive techniques, p.275-281, August 23-25, 1978
• 3: Franklin C. Crow, Shadow algorithms for computer graphics, Proceedings of the 4th annual conference on Computer graphics and interactive techniques, p.242-248, July 20-22, 1977, San Jose, California
• 4: Tomoyuki Nishita , Isao Okamura , Eihachiro Nakamae, Shading models for point and linear sources, ACM Transactions on Graphics (TOG), v.4 n.2, p.124-146, April 1985 [doi>10.1145/282918.282938]
• 5: Bouknight, J., and Kelly, K., "'An algorithm for producing halftone computer graphics presentations with shadows and movable light sources," SJCC, AFIPS, Vol 36 (1970), pp. 1-10.
• 6: Turner Whitted, An improved illumination model for shaded display, Communications of the ACM, v.23 n.6, p.343-349, June 1980 [doi>10.1145/358876.358882]
• 7: Robert L. Cook , Thomas Porter , Loren Carpenter, Distributed ray tracing, Proceedings of the 11th annual conference on Computer graphics and interactive techniques, p.137-145, January 1984
• 8: Gary Scott Watkins, A real time visible surface algorithm, 1970
• 9: Sproull, Robert, and Newman, William, "'Principles of Interactive Computer Graphics" (first edition is better on this subject), McGraw Hill, New York (1973).
• 10: David F. Rogers, Procedural elements for computer graphics, McGraw-Hill, Inc., New York, NY, 1984
• 11: James F. Blinn, Light reflection functions for simulation of clouds and dusty surfaces, Proceedings of the 9th annual conference on Computer graphics and interactive techniques, p.21-29, July 26-30, 1982, Boston, Massachusetts, United States
• 12: Nelson Max, Light diffusion through clouds and haze, Computer Vision, Graphics, and Image Processing, v.33 n.3, p.280-292, March 1986 [doi>10.1016/0734-189X(86)90177-5]
• 13: James T. Kajiya , Brian P Von Herzen, Ray tracing volume densities, Proceedings of the 11th annual conference on Computer graphics and interactive techniques, p.165-174, January 1984
• 14: Perlin, Ken, "State of the Art in Image Synthesis '85 Course Notes," ACM SIGGRAPH '85, course 11.
• 15: Michael E. Mortenson, Geometric modeling, John Wiley & Sons, Inc., New York, NY, 1985
• 16: D. F. Rogers , J. A. Adams, Mathematical elements for computer graphics (2nd ed.), McGraw-Hill, Inc., New York, NY, 1989
• 17: Ed Catmull , Alvy Ray Smith, 3-D transformations of images in scanline order, Proceedings of the 7th annual conference on Computer graphics and interactive techniques, p.279-285, July 14-18, 1980, Seattle, Washington, United States
• 18: Nelson L. Max, Antialiasing Scan-Line Data, IEEE Computer Graphics and Applications, v.10 n.1, p.18-30, January 1990 [doi>10.1109/38.45807]
• 19: Jules Bloomenthal, Modeling the mighty maple, Proceedings of the 12th annual conference on Computer graphics and interactive techniques, p.305-311, July 1985
• 20: N L Max, Shadows for bump-mapped surfaces, Proceedings of Computer Graphics Tokyo '86 on Advanced Computer Graphics, p.145-156, June 1986, Tokyo, Japan

INDEX TERMS

Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.3 Picture/Image Generation
          Subjects: Display algorithms

General Terms:
Algorithms