Lets grab the coolest results first:
A cornellbox with one mirror-cube. Notice the color bleeding from diffuse interreflection on the different surfaces. The effect is most noticeable on the right cube and on the floor, but carry throughout the scene. We can also see some artifacts from the kernel gathering as theres are green and red dots (although blurry) on some of the surfaces. We are still trying to get to the bottom of why those artifacts appear!
A cornell box a mirror and a glass ball. You can see diffuse interreflection on all surfaces but also caustic effects as the photons are focused in the right sphere. There are kernel gather artifacts, but they are quite subtle.
Another really cool cornell box scene, with water! Underneath the water surface you can see the classic caustic effects from fluids in motion!
Here are some cool screenshots along the way:
Visualization of the photons that we store in our photon map! The colour is derived from the power of that photon
Notice how caustic effects are captured as the photons are scattered through the ball of glass. These photons are sometimes collected in a separate caustics-map but we use a global photon map as for the moment.
A first attempt at photon gathering. Here the kernel size is fixed and without any falloff, yielding the (very) clear artifacts in the form of circles.
After adding some falloff to each kernel, meaning that the photons gather at a specific point x are weighted differently if they are closer or further from that point. We still find interesting artifacts on surfaces viewed through scattering surfaces (the dots).
Here is another scene rendered with the new indirect lightning from photon final gathering. You can clearly see the kernel size in this rendering too. Also, both this scene and the last is very bright. PS: yes there is a mouse in the screenshot