Did the diffuse reflection reconstruction rely on high speed photography? Or a special geometric setup of the reflector? Trying to think of how this could work.
https://dl.acm.org/doi/10.1145/1186822.1073257
"We present a novel photographic technique called dual photography, which exploits Helmholtz reciprocity to interchange the lights and cameras in a scene. With a video projector providing structured illumination, reciprocity permits us to generate pictures from the viewpoint of the projector, even though no camera was present at that location."
I recommend watchign the video from the paper for good explains and demonstrates the technique. It's very impressive work.