Path Tracing

An introduction to path tracing - a realistic rendering algorithm. Watch the original presentation here: https://youtu.be/x4oQsQ76OHY

Transcript

1. Path Tracing Michael Fogleman September 2015 a.k.a. sweet graphics
2. The Code speakerdeck.com/fogleman github.com/fogleman/pt These Slides
3. Path tracing is a realistic rendering algorithm that simulates light bouncing around a scene.
5. “Global illumination” takes into account not only the light which comes directly from light sources (direct illumination), but also light rays that are reflected by other surfaces (indirect illumination). “Path tracing” falls under the umbrella of “global illumination” algorithms.
6. The “Rendering Equation” Uhh…
7. The “Rendering Equation” • Its own light output (emittance), and • The sum total of reflected light from all directions In layman’s terms, an object’s color depends on:
8. Monte Carlo • Path tracing is a randomized “Monte Carlo” algorithm • Simulate billions of random light rays bouncing around the scene • Hundreds or thousands of rays per pixel • Random = different results each time you run it • More rays = less noise in the image
10. Basic Algorithm • For each pixel: • Cast a ray from the camera and through the pixel • Determine the nearest object in the scene that the ray intersects • Cast shadow ray(s) to determine direct lighting • Recursively cast more rays to determine indirect lighting, until some maximum depth is reached
11. Bounces (Recursion Depth)
12. Bounces: 0
13. Bounces: 1
14. Bounces: 2
15. Bounces: 3
16. Bounces: 4
17. Bounces: 8
18. Bounces: 16
19. Noise
20. Iterations: 1
21. Iterations: 2
22. Iterations: 4
23. Iterations: 8
24. Iterations: 16
25. Iterations: 64
26. Materials
28. Diffuse Specular Glossy Tinted Clear Mirror
30. Shapes • Spheres • Cubes • Triangles • Triangle Meshes • OBJ • STL
31. k-d tree
32. Textures
33. Examples
40. How does this differ from other rendering techniques?
41. OpenGL
42. Also OpenGL
43. Live Coding Demo