1. Depth-of-Field Rendering with Multiview Synthesis SigGraph Asia 2009 Sungkil Lee, Elmar Eisemann, and Hans-Peter Seidel Sunyeong Kim Nov. 2 nd. 2010

2. 2 GOAL ● GPU-based real time rendering method ● High-quality Depth-of-Field effect ● Similar in quality to multiview accumulation methods.

3. 3 BASIC KNOWLEDGE ● Depth of Field (DOF) ● Circle of Confusion (COC) ● Thin-lens Model

4. 4 DOF & COC

5. 5

6. 6 THIN-LENS MODEL

7. 7 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

8. 8 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

9. 9 Scene Decomposition ● Single render pass scene decomposition ● The depth intervals δ are uniformly with respect to the signed COC radius C(d)

10. 10 Scene Decomposition Video

11. 11 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

12. 12 Layer Creation ● On current hardware ● Multiple render targets do not allow independent z-buffer ● Texture Tiling ● “Layered rendering” ● Pixel depth, corresponding layer L ● Approximation – not split triangles at the layer boundary

13. 13 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

14. 14 DOF Blur ● Using Layered Representation

15. 15 DOF Blur ● Ray Traversal ● Each layer represents a height field. ● Iterative approximation inspired by the Method of False Position.

16. 16 DOF Blur ● Handling Off-Screen Pixels ● Decomposition from the lens center ● Discard all rays that leave the frustum ● Early Layer Culling ● Large blank image areas ● Skipping intersection test ● If a minimum depth value is greater than the depth bounds of the layer, No intersection & test skip!

17. 17 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

18. 18 Cone Tracing ● Need sufficient lens samples ● Rays are continuous ● Single ray only result in one precise point ● Rays to Cone! ● correspond to an infinite ray set centered around the original ray ● lead to higher quality

19. 19 Approximate Cone Tracing ● Cone Tracing ● correspond to an infinite ray set centered around the original ray ● lead to higher quality ● Using Mipmap with alpha channel and average color

20. 20 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

21. 21 Jittered Lens Sampling ● Insufficient sampling leads to visible aliasing artifact

22. 22

23. 23 RESULT

24. 24 RESULT

25. 25 DISCUSSION ● Pros ● Faster to multiview accumulation method ● Highly scalable with the number of views and layers ● Cons ● The lack of anti-aliasing ● Trade-off : performance ↔ accuracy This method is good to produce high-quality DOF blur in real time.

26. 26 CONCLUSION ● Trade-off : performance ↔ accuracy This method is good to produce high-quality DOF blur in real time.

27. 27 Thank you! Question or Comment?