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Non-Photorealistic Rendering FORMS

Non-Photorealistic Rendering FORMS. Threshold dependent. Model dependent. View dependent. Silhouette. Boundary. Outline form of the object. X. Crease (+ other discontinuities). Crease (+ other discontinuities). Interior form of the object. X. Silhouette Algorithms.

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Non-Photorealistic Rendering FORMS

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  1. Non-Photorealistic RenderingFORMS

  2. Threshold dependent Model dependent View dependent Silhouette Boundary Outline form of the object X Crease (+ other discontinuities) Crease (+ other discontinuities) Interior form of the object X

  3. Silhouette Algorithms • Object Space • Involve computations in 3D and produce a list of silhouette edges or curves for a given viewpoint • Brute Force • Edge Buffer • Probabilistic • Gauss Map Arc Hierarchy • Normal Cone Hierarchy • Implicit Surfaces • NURBS Surfaces • Image Space • involve image processing techniques • Two Pass Methods • Environment Map • One Pass Method • Model Augmentation • Depth Discontinuity Methods

  4. Object Space  2. Edge Buffer Using the “Edge Buffer” data structure of Buchanan and Sousa to iterate over facets instead of edges. Buchanan, J. W. and Sousa, M. C.The edge buffer: A data structure for easy silhouette renderingProc. of NPAR '00

  5. Pre-Processing  Construct the Edge-Buffer ?

  6. Pre-Processing  Construct the Edge-Buffer V = vertex id F = front face ? B = back face ?

  7. Pre-Processing  Construct the Edge-Buffer V = vertex id F = front face ? B = back face ?

  8. T (2, 3, 1) Sort Indices… (1, 2, 3)

  9. InsertEdge (1, 2) T (2, 3, 1) (1, 2, 3)

  10. InsertEdge (1, 2) T (2, 3, 1) (1, 2, 3)

  11. InsertEdge (1, 2) T (2, 3, 1) (1, 2, 3)

  12. InsertEdge (1, 2) T (2, 3, 1) (1, 2, 3)

  13. InsertEdge (1, 2) InsertEdge (1, 3) T (2, 3, 1) (1, 2, 3)

  14. InsertEdge (1, 2) InsertEdge (1, 3) T (2, 3, 1) (1, 2, 3)

  15. InsertEdge (1, 2) InsertEdge (1, 3) T (2, 3, 1) (1, 2, 3)

  16. InsertEdge (1, 2) InsertEdge (1, 3) InsertEdge (2, 3) T (2, 3, 1) (1, 2, 3)

  17. T (2, 3, 1)

  18. T (4, 1, 3) Sort Indices… (1, 3, 4)

  19. InsertEdge (1, 3) InsertEdge (3, 4) InsertEdge (1, 4) T (4, 1, 3) (1, 3, 4)

  20. InsertEdge (1, 3)  already in InsertEdge (3, 4) InsertEdge (1, 4) T (4, 1, 3) (1, 3, 4)

  21. InsertEdge (1, 3) InsertEdge (3, 4) InsertEdge (1, 4) T (4, 1, 3) (1, 3, 4)

  22. InsertEdge (1, 3) InsertEdge (3, 4) InsertEdge (1, 4) T (4, 1, 3) (1, 3, 4)

  23. T (4, 1, 3)

  24. T (1, 2, 5)

  25. T (1, 2, 5)

  26. T (1, 2, 5)

  27. T (1, 2, 5)

  28. T (5, 3, 2) T (5, 4, 3) T (1, 4, 5)

  29. Run-Time  for (each new frame) do…

  30. T (2, 3, 1) ?

  31. T (2, 3, 1)

  32. UpdateEB (1, 2, front) UpdateEB (2, 3, front) UpdateEB (1, 3, front) T (2, 3, 1) Sort Indices… (1, 2, 3)

  33. F bit XOR 1 UpdateEB (1, 2, front) UpdateEB (2, 3, front) UpdateEB (1, 3, front) T (2, 3, 1) Sort Indices… (1, 2, 3)

  34. T (4, 1, 3)

  35. F bit XOR 1 UpdateEB (1, 3, front) UpdateEB (3, 4, front) UpdateEB (1, 4, front) T (4, 1, 3) Sort Indices… (1, 3, 4)

  36. F bit XOR 1 UpdateEB (1, 3, front) T (4, 1, 3) Sort Indices… (1, 3, 4)

  37. F bit XOR 1 UpdateEB (1, 3, front) T (4, 1, 3) Sort Indices… (1, 3, 4)

  38. F bit XOR 1 UpdateEB (1, 3, front) UpdateEB (3, 4, front) UpdateEB (1, 4, front) T (4, 1, 3) Sort Indices… (1, 3, 4)

  39. T (1, 2, 5)

  40. B bit XOR 1 UpdateEB (1, 2, back) UpdateEB (2, 5, back) UpdateEB (1, 5, back) T (1, 2, 5)

  41. B bit XOR 1 UpdateEB (1, 2, back) UpdateEB (2, 5, back) UpdateEB (1, 5, back) T (1, 2, 5)

  42. T (5, 3, 2) T (5, 4, 3) T (1, 4, 5)

  43. How to Interpret the Bit Fields? FB = 11  Silhouette Edges FB = 00  Interior Edges

  44. 3D Perception???

  45. 3D Perception???

  46. Artist designates which interior edges are always drawn

  47. Boundaries FB = 01 FB = 10 Artist designates which interior edges are always drawn

  48. Artist Edges Artist designates which interior edges are always drawn AFBFaBa Artist Edge? Absolute Front? Absolute Back? 10001 When a front facing edge is being updated we simply OR the current value of Fa with 1, similarly for Ba 10010

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