If we are tracing a path from the camera as well as from the light, the chance that the 2 paths will meet seems to be essentially 0. How will we find intersecting paths?
keenan
@potato You don't find intersecting paths---you make them. I.e., you trace a "light subpath" and an "eyesubpath," then test whether the segment connecting their endpoint hits anything. If not, you make a (careful) contribution of the radiance along this path to the overall estimate.
If we are tracing a path from the camera as well as from the light, the chance that the 2 paths will meet seems to be essentially 0. How will we find intersecting paths?
@potato You don't find intersecting paths---you make them. I.e., you trace a "light subpath" and an "eyesubpath," then test whether the segment connecting their endpoint hits anything. If not, you make a (careful) contribution of the radiance along this path to the overall estimate.