Second-Order Feed-Forward Rendering for Specular and Glossy Reflections

1. Second-Order Feed-Forward Rendering for Specular and Glossy Reflections Lili Wang1, Naiwen Xie1, Wei Ke2,Voicu Popescu3 1State Key Laboratory of Virtual Reality Technology and Systems, Beihang University 2MacaoPolytechnic Institute, Macau 3Purdue University, West Lafayette

2. Motivation Realistic rendering

3. Previous Works • Ray-tracing • Real-Time Reflection using Ray Tracing with Geometry Field[S. Li et al.2006] • KD-tree acceleration structures for a GPU raytracer[T. Foley et al.2005] • An improved illumination model for shaded display[Commun.1980] • NVIDIA OptiX ray tracing engine • Image Based Rendering • Irradiance gradients[G.J.Ward 2008] • Real-Time Reflection Mapping with Parallax[J. Yu et al.2005] • Light field techniques for reflections and refractions[W. Heidrich et al.1999] [S. Li et al.2006] [W. Heidrich et al.1999]

4. Previous Works Projection methods Accurate Specular Reflections in Real-Time [Roger D et al.2006] Real-time Multi-perspective Rendering on Graphics Hardware[X Hou et al.2006] Interactive reflections on curved objects[Ofek E et al.1998] Reflected-scene approximation methods Reflected-Scene Impostors for Realistic Reflections at Interactive Rates[Popescu V. et al.2006] Approximate Ray-Tracing on the GPU with Distance Impostors[Szirmay‐Kalos L et.al 2005] [X Hou et al.2006 ] [Szirmay‐Kalos L et.al 2005]

5. Main idea Normal Camera View Object Planar reflector Planar Surface Mirror Eye

6. Main idea Normal Reflected ray Camera View Fitting plane Concave reflector Mirror Eye

7. Our Algorithm Input Scene For each Cluster Generate Camera Final Effect Screen Space Cluster Ray Intersection Render Impostor

8. Scene Preprocess Scene are semantically subdivisioned The scene is modeled with triangles. Objects are labeled with ID.

9. Screen Space cluster

10. Camera Generation A compact camera model

11. Impostor Rendering • Rendering the depth-image as a impostor

12. Ray Intersection • Ray intersection with Colored Depth Image Cluster Camera Eye te ts ImposterImage Plane S Cluster Points （reflective points） P Output Camera Eye E Reflected object

13. Glossy Effect • Setting camera far plane based on glossy level • Intersect several reflected rays with the depth image Glossy

14. Quality Our image is comparable to the ray tracing Our Method Ray-tracing

15. Quality • There is hardly any error compared to ray-tracing Error of toilet scene Error of toilet living room

16. Quality Sample rates Bilinear interpolation of samples(G-buffer) Sample directly with geometry(Ray tracing) Sample Error

17. Quality Disocclusion error 11 clusters 24 clusters 38 clusters

18. Quality • Our method is much faster than ray-tracing Performance of Our Method Compared to Optix

19. Limitation Disocclusion errors Image resampling Partitioning scene geometry Higher-order reflections Concave reflectors

20. Future Works Cone Tracing Glossy Effect Inspired by Cone Tracing[Crassin. et al.2011] LOD of depth image [Crassin.2011]

21. Questions?