Search found 17 matches

by Igors
Mon Apr 23, 2012 5:25 pm
Forum: General Development
Topic: Importance Sampling
Replies: 11
Views: 8815

Re: Importance Sampling

You have plenty of options: Instant radiosity, photon mapping, irradiance caching, radiance caching, bidirectional path tracing, metropolis light transport, SPPM, ... I'm asking about how to reduce noise/variance when one/single point is sampled. I realize the N (count of rays specified by user) ca...
by Igors
Mon Apr 23, 2012 8:06 am
Forum: General Development
Topic: Importance Sampling
Replies: 11
Views: 8815

Importance Sampling

Hi All I've implemented a simplest unbiased Monte-Carlo for indirect illumination - N rays are cast from point to hemisphere. It works but becomes very noisy for scenes with "bright spots", e.g. when a relative small area is lit a lot. In others areas only few rays (of all N) catch the spot, so need...
by Igors
Sat Apr 14, 2012 9:34 am
Forum: General Development
Topic: Splattering Samples
Replies: 0
Views: 2591

Splattering Samples

Hi All I need to splatter samples: select/mark some 3D points from initial given set/cloud of points. Each sample has an influence radius (adjusted in sampling process), my goal is to cover the whole (big) cloud with relative small amount of samples. My actual implementation is workable but slow and...
by Igors
Sat Apr 14, 2012 3:46 am
Forum: General Development
Topic: Ray differentials and progressive rendering
Replies: 3
Views: 4209

Re: Ray differentials and progressive rendering

You can peek this technique in open-sources (in old Yafaray for example) and modify for your needs
by Igors
Wed Jan 11, 2012 11:33 am
Forum: General Development
Topic: Irradiance interpolation issues
Replies: 6
Views: 5472

Re: Irradiance interpolation issues

Come to think of it, there's one trick I did that might help you: in addition to the mean distance, my cache entries hold the directon of the ray with the smallest distance. At lookup time, I compare it to the vector between sample and lookup location and depending on their orientation I shrink the...
by Igors
Tue Jan 10, 2012 10:57 am
Forum: General Development
Topic: Irradiance interpolation issues
Replies: 6
Views: 5472

Re: Irradiance interpolation issues

Hi, Matt, Stefan, All Thanks for your replies. I use regular grid for primary (directly visible) points and standard technique for secondary points (reflected and refracted). The primary cache is much better and faster. Gradients can be on/off, for some scenes their effect is positive, but not for o...
by Igors
Sat Jan 07, 2012 12:25 pm
Forum: General Development
Topic: Irradiance interpolation issues
Replies: 6
Views: 5472

Irradiance interpolation issues

Hi All My task is to interpolate irradiance samples. I realize it's well-known algorithm, so I'm reading Krivanek's and others pdf(s) and looking open-sources. There are several issues I cannot resolve Issue #1: obscured samples *S1 *S2 *T Here S = precalculated samples and T is a point where irradi...