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Google Summer of Code 2017

Weekly Report on Many-light Sampling Method

Goal of the project is to integrate the new many-light sampling algorithm proposed by Nathan Veghdal

1. May 15^th - May 30^th (Community Bonding Period)

2. May 31^st – June 2^nd

3. June 5^th - June 9^th

4. June 12^st – June 16^th

5. June 19^th – June 23^rd

6. June 26^th – June 30^th

7. July 3^rd – July 7^th

8. July 10^th – July 14^th

9. July 17^th – July 21^st

10. July 24^th – July 28^th

11. July 31^st – August 4^th

12. & 13. August 7^th - August 18^th

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• SAH partitioner without split stop

SAH partitioner without the split cost stop - comparison
SAH + squared distance
SAH + solid angle
CDF

Squared distance node prob evaluation
converging 1s
LT + SAH partitioner
LT + Middle partitioner
CDF

Nathan's LightTree tests

Appleseed 2 Psychopath comparison
Appleseed	Psychopath
16spp
Middle Partitioner + squared distance
	n/a
Middle Partitioner + solid angle
	n/a
SAH Partitioner + squared distance
SAH Partitioner + solid angle

Currently working on:

• Implement proprietary LightTree partitioner
  • partitions lights based on:
    • surface
    • intensity
    • orientation
• FIX the rendering artefact in the EMT-NPL scene
• Add reference in the code to the used article

LightTree seem to be working a bit slower than the CDF approach for small number of light sources.

• Produce many light test scenes
  • many NPL light sources
  • many EMT light sources
  • many mixed light sources

Ideas on Implementing Light Tree Sampling Based on the Light Orientation

• Cone of normals
• K-means of children vertices

Optimization TODO

• Store items within the LightTree nodes
• Store bbox node info within the node itself
• Reduce number of variables set by recursive_node_update() (i.e. variables which can be set during the building time)

Collection of useful papers

• A Spherical Cap Preserving Parameterization for Spherical Distributions, 2017
• Importance Sampling of Many Lights With Adaptive Tree Splitting