I wonder how you get such clean results in the GI using path tracing. Do you also calculate the direct light at each hit point of the path? Otherwise most paths wouldn’t ever reach the small area light source and thus resulting in a dark pixel color. Or do you use some kind of importance sampling?
The other question I would like to know is how do you use the cuda threads? Are you using bucket-rendering or some kind of image partitioning? Or do you use other techniques to avoid the watchdog time-out? Do you sum up the sampling values in your kernel or outside using the cpu?

Thanks in advance.

Daniel