This is interesting, there has been research work on doing something similar in Monte Carlo particle transport, which is the same idea as ray tracing but with d

This is interesting, there has been research work on doing something similar in Monte Carlo particle transport, which is the same idea as ray tracing but with different physics (higher energies, different types of particles, more complex physical interactions like incoherent scatter etc). Still reading, but this article appears to be based on the same general idea albeit with a different objective. Differentiation of particle transport Monte Carlo codes is focused on different types of tallies and subsequently computing their sensitivities. The inverse rendering problem in 5.3 is actually also broadly applicable to fields like nuclear security and emergency response.