apaffy wrote:Well, my understanding is that unless you have non-specular bounces within some medium, the two boundaries (in and out of the medium) cancel out and it does not affect the image.
I've always been interested in implementing the basic radiance approach described by Veach, but not yet attempted it. Would someone that has implemented this be willing to share any tips/insights into this approach?
My understanding is that they not completely cancel out. Even a perfect mirror BSDF is based on fresnel law and so, some absorption is still possible. So, you can't cancel everything. By example, if you use a IOR of 1.5 then you will have a 'dark mirror'. So, your pdf = 1 if the Wi is the exact reflected direction, in the other case your pdf = 0. So, it mean that you still have to account for the BSDF in most cases (except connection).
But, no sure it answer your question
You can check Mitsuba renderer, they also account for this correction (Just in the last version they only account for 1/eta and not 1/eta², don't know why).
I have finally implement it and it result that my refraction are darker, I don't know why... maybe I have a problem with my MIS (I have to check this when I have some free time