Here are some PBRT renders I made, to compare between using photon mapping and using regular raybouncing. I recompiled PBRT with the advanced Photon Mapping Integrator (C++ code available here) to speed up the Final Gathering algorithm. There’s still a lot of noise in the final image, but the caustics are clearly visible.
I’ve also made a (failed) attempt at subsurface scattering, but it’s a nice render anyway:
