paper presentation - micropolygon ray tracing with defocus and motion blur -
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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=0T=1
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.