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Shadow Mapping Outline Quick introduction to computer graphics. - PowerPoint PPT Presentation

Shadow Mapping Outline Quick introduction to computer graphics. Why Shadows ? The shadow mapping algorithm. Strengths and weaknesses You will ... Get an abstract view of how Computer Graphics works. Be able to outline the


  1. Shadow Mapping

  2. Outline  Quick introduction to computer graphics.  Why Shadows ?  The shadow mapping algorithm.  Strengths and weaknesses

  3. You will ...  Get an abstract view of how Computer Graphics works.  Be able to outline the the shadow mapping algorithm.  Know that this technique is used in current games.  Be able to list some weaknesses and strengths of shadow mapping.

  4. Computer graphics  A set of data: triangles in 3D space.  Provided by an artist.  Methods of “rendering” (Drawing) these triangles on a computer screen.  Developed by a programmer.

  5. Computer Graphics: the artist 1.000000 1.000000 -1.000000 0.000000 0.000000 -1.000000 1.000000 -1.000000 -1.000000 0.000000 0.000000 -1.000000 -1.000000 -1.000000 -1.000000 0.000000 0.000000 -1.000000 -1.000000 1.000000 -1.000000 0.000000 0.000000 -1.000000 1.000000 0.999999 1.000000 0.000000 -0.000000 1.000000 -1.000000 1.000000 1.000000 0.000000 -0.000000 1.000000 -1.000000 -1.000000 1.000000 0.000000 -0.000000 1.000000 0.999999 -1.000001 1.000000 0.000000 -0.000000 1.000000 1.000000 1.000000 -1.000000 1.000000 -0.000000 0.000000 1.000000 0.999999 1.000000 1.000000 -0.000000 0.000000 0.999999 -1.000001 1.000000 1.000000 -0.000000 0.000000 1.000000 -1.000000 -1.000000 1.000000 -0.000000 0.000000 1.000000 -1.000000 -1.000000 -0.000000 -1.000000 -0.000000 0.999999 -1.000001 1.000000 -0.000000 -1.000000 -0.000000 -1.000000 -1.000000 1.000000 -0.000000 -1.000000 -0.000000 -1.000000 -1.000000 -1.000000 -0.000000 -1.000000 -0.000000 -1.000000 -1.000000 -1.000000 -1.000000 0.000000 -0.000000 -1.000000 -1.000000 1.000000 -1.000000 0.000000 -0.000000 -1.000000 1.000000 1.000000 -1.000000 0.000000 -0.000000 -1.000000 1.000000 -1.000000 -1.000000 0.000000 -0.000000 1.000000 0.999999 1.000000 0.000000 1.000000 0.000000 1.000000 1.000000 -1.000000 0.000000 1.000000 0.000000 -1.000000 1.000000 -1.000000 0.000000 1.000000 0.000000 -1.000000 1.000000 1.000000 0.000000 1.000000 0.000000

  6. Computer Graphics: the programmer 1.000000 1.000000 -1.000000 0.000000 0.000000 -1.000000 1.000000 -1.000000 -1.000000 0.000000 0.000000 -1.000000 -1.000000 -1.000000 -1.000000 0.000000 0.000000 -1.000000 -1.000000 1.000000 -1.000000 0.000000 0.000000 -1.000000 1.000000 0.999999 1.000000 0.000000 -0.000000 1.000000 Read data -1.000000 1.000000 1.000000 0.000000 -0.000000 1.000000 -1.000000 -1.000000 1.000000 0.000000 -0.000000 1.000000 0.999999 -1.000001 1.000000 0.000000 -0.000000 1.000000 1.000000 1.000000 -1.000000 1.000000 -0.000000 0.000000 1.000000 0.999999 1.000000 1.000000 -0.000000 0.000000 0.999999 -1.000001 1.000000 1.000000 -0.000000 0.000000 1.000000 -1.000000 -1.000000 1.000000 -0.000000 0.000000 1.000000 -1.000000 -1.000000 -0.000000 -1.000000 -0.000000 0.999999 -1.000001 1.000000 -0.000000 -1.000000 -0.000000 -1.000000 -1.000000 1.000000 -0.000000 -1.000000 -0.000000 -1.000000 -1.000000 -1.000000 -0.000000 -1.000000 -0.000000 -1.000000 -1.000000 -1.000000 -1.000000 0.000000 -0.000000 -1.000000 -1.000000 1.000000 -1.000000 0.000000 -0.000000 -1.000000 1.000000 1.000000 -1.000000 0.000000 -0.000000 -1.000000 1.000000 -1.000000 -1.000000 0.000000 -0.000000 1.000000 0.999999 1.000000 0.000000 1.000000 0.000000 1.000000 1.000000 -1.000000 0.000000 1.000000 0.000000 -1.000000 1.000000 -1.000000 0.000000 1.000000 0.000000 View Position -1.000000 1.000000 1.000000 0.000000 1.000000 0.000000 Graphics Processing Unit Light Position Material Specification

  7. Computer Graphics: The GPU View Position Color Buffer Graphics Light Position Processing Material Specification Unit Depth buffer

  8. Why Shadows ?

  9. Shadow mapping: Step one. Color Buffer View Position View from Light Position Graphics Processing Unit Light Position Shadow Map! Depth buffer Material Specification

  10. How does it work?

  11. Shadow mapping: Step two. Color Buffer Graphics Processing Unit Depth buffer Shadow Map! View Position Graphics Processing Unit Light Position Material Specification Depth buffer

  12. Strengths  Price/Performance ratio.  Linear cost in number of drawn “triangles”.  Extensible.  Simple.

  13. Problems  Detached shadows.  Incorrectly shadowed surfaces.

  14. Causes and possible solutions. Sampling related problems.  Increase shadowmap  resolution. Add small constant to  “distances” in order to avoid self-shadowing. Very unstable! 

  15. Even in professional products.

  16. The end! We have seen...   Very high level introduction to Computer graphics.  How shadows enhance realism.  Shadow mapping.  Currently popular algorithm for generating shadows.  Good performance.  Reasonable results.  But unstable! (small changes to input...)  Research topic: see GPU Gems 3. GPU Pro. (new articles on the topic still popping up)

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