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Paper Presentation - Micropolygon Ray Tracing With Defocus and Motion Blur -

Paper Presentation - Micropolygon Ray Tracing With Defocus and Motion Blur -. Qiming Hou, Hao Qin, Wenyao Li, Baining Guo, Kun Zhou Presenter : Jong Hyeob Lee 2010. 10. 28. Micropolygon. What is a micropolygon? Polygon Micropolygon.

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Paper Presentation - Micropolygon Ray Tracing With Defocus and Motion Blur -

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  1. Paper Presentation - Micropolygon Ray Tracing With Defocus and Motion Blur - Qiming Hou, Hao Qin, Wenyao Li, Baining Guo, Kun Zhou Presenter : Jong Hyeob Lee 2010. 10. 28

  2. Micropolygon • What is a micropolygon? Polygon Micropolygon

  3. Defocus and Motion Blur

  4. Rasterization vs Ray Tracing • Tracing a ray is slower than rasterizing a pixel. • Every ray returns something useful. Rasterization waste time on not-covered or occluded pixels. • Tradeoff between per-operation cost and useful operation percentage. • Stochastic sampling favors ray tracing.

  5. Goal • A 4D micropolygon ray tracing • Performs up to an order of magnitude faster than rasterization. • Eliminates the quality-performance tradeoff in defocus and motion blur rendering.

  6. Related Works • Micropolygon • Reyes [Cook et al. 1987] • RenderAnts [Zhou et al. 2009] • Defocus and Motion Blur • Adaptive sampling [Hachisuka et al. 2008] • Hyper-trapezoids • Collision detection [Hubbard 1995]

  7. Overview • Hyper-trapezoid • BVH Construction • Ray Generation • BVH Traversal

  8. Overview • Hyper-trapezoid • BVH Construction • Ray Generation • BVH Traversal

  9. Hyper-trapezoid • A hyper-trapezoid is… • Two faces at T=0, T=1 interpolated linearly across T

  10. Hyper-trapezoid • Axis-aligned bound box & Bounding box based hyper-trapezoid

  11. Hyper-trapezoid • 4D OBB hyper-trapezoids • The T=0 and T=1 faces are 3D OBB, analogous to 3D Hyper-trapezoids with 2D Bouding Box faces. T=1 T=0

  12. Comparisons with AABB • Test scenes (Furball, Ladybug, Fairy, Car)

  13. Comparisons with AABB

  14. Overview • Hyper-trapezoid • BVH Construction • Ray Generation • BVH Traversal

  15. BVH Construction • Basic topology is the same as general BVH.

  16. BVH Construction • Build process • Top level BVH • In-grid level BVH • Compute bounding volume

  17. BVH Construction • Top level BVH • Unit : Micropolygon grid • Split strategy : Surface Area Heuristic • Termination criterion : One gird in every node

  18. BVH Construction • In-grid level BVH • Unit : Micropolygons • Split strategy : Parametric space mid-split • Termination criterion : Less than 8 micropolygons in a node

  19. BVH Construction • Compute bounding volume • Compute grid-level orientation • Bottom-up merge : use the orientation that results in smaller surface area. • Top-down simplify : use parent node’s orientation if surface area isn’t increased too much.

  20. Overview • Hyper-trapezoid • BVH Construction • Ray Generation • BVH Traversal

  21. Ray Generation • Reducing the alias • Lens permutation : magic square • Time permutation : magic square shuffled and shifted per-pixel

  22. Overview • Hyper-trapezoid • BVH Construction • Ray Generation • BVH Traversal

  23. BVH Traversal – Ray and OBB • Transforming rays into per-box local frame.

  24. BVH Traversal – Ray and OBB • Transforming rays into per-box local frame.

  25. BVH Traversal - Micropolygon • Use a rasterization-like method to compute pseudo-intersections for micropolygons. • Project micropolygon to view plane. • Use even-odd rule to test it.

  26. Comparison with Rasterization • Better quality

  27. Comparisons with AABB • Test scenes (Furball, Ladybug, Fairy, Car)

  28. Comparison with Rasterization • Faster sampling time

  29. Result – Total rendering time

  30. Conclusion • The first time ray tracing is faster than rasterizaion. • A novel acceleration structure based on oriented hypertrapezoid. • Limitation : • Inefficiency of transparency handling • The BVH is not effective when tracing rays inside objects over rasterization methods.

  31. Q&A • Thank you.

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