First line is great! Something happened to your maths between the first and second lines, your pdf conversions are not correct. Your final equation will contain P_A(x0) and P_A(x5) as I noted above!apaffy wrote:You'll end up with an equation that contains:

* P_A(x0) and P_A(x5)

*Edit: actually I already wrote down the final sample equation for 4 vertices on viewtopic.php?f=3&t=516&start=30#p1436 if you wanted a hint (although in this post please note P(x->x') is wrt projected solid angle).*

You mean P(x0->x1) and *P(x5->x4)*.spectral wrote:What are the values of P(x0->x1) and P(x4->x5)?

P(x0->x1) is defined by the angular emission model of your light source. For emitters that emit hemispherically from a surface, this looks a lot like Lambertian reflectance.

P(x5->x4) is defined by the angular emission model of your camera. This usually computed by sampling the film from a fixed point on the aperture, then converting this into an angular pdf.