Thursday, May 3, 2012

Multiple Importance Sampling

Today I finally got a verifably correct implementation of direct lighting MIS. Here're two comparison images, each at 5spp. There's a large area light, and the surface is glossy Phong with a 100000 exponent (very hard for light sampling)

MIS (5 spp)
No MIS (5 spp)
My original MIS implementation randomly selected either light sampling or brdf sampling. While it kind of worked, it did introduce a lot more variance into the image. The current MIS implementation reuses the surface's indirect brdf sample as the light's brdf sample.

And here's a render of the Cornell box.
Glossy Cornell box (800 spp)
Reference rendered in Maxwell

1 comment:

  1. Results will be much noticeable if you will use Veach's example scene. :) ;) Here is my implementation with full source code: