Photon Tracing

Posted: October 31, 2011 in RayTracing

Today I added photon tracing. Its only Caustic photons at the moment, but the improvement in speed and visual quality is much better now, and I’ve still yet to thread the 1st pass photon generation stage. As mental ray does, I only trace photons at geometry in the scene that reflect or refract, to save on wasted caustic photons. This is done by querying for all geometry with a specular type material, retrieving their AABBs and then shooting photons from the lights at these boxes. A lot of geometry really doesnt get bounded very well by AABBs, such as the teapot below, so I also added the option to keep shooting photons until the target count is matched, as opposed to just storing the ones that do hit. This takes a little longer, but it means less fiddling with the multipliers to get descent results.

The images below all use point lights.


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