I rewrote the radiosity solution over the weekend, this time for the Voxel Farm. Here you can see some results for the same forest scene of the earlier video:
It is a bit tricky to understand the light in these pictures. Primary light sources like the sun and the sky are not shown here. You can only see the light that has bounced off the surfaces or went through the tree crowns, which are translucent.
There are no materials or any texturing. The green hue comes from the crowns and parts of the ground that are covered by grass. But don't pay too much attention to the colors. This was to see if the algorithm was working properly. Also keep in mind the crown polygons are there only to collect, scatter and reflect illumination. They are replaced by the instanced leaves.
I found I needed to get up to 20 bounces to get enough illumination down to the forest ground. Otherwise it was too dark.