Igors wrote:I've not this understanding and would be interested in explanations if possibleapaffy wrote:* Understanding how the geometry term is used to convert pdfs between projected solid angle and area

Thanks

I think the best I can do is direct you towards sections 8.1 and 8.2 of the Veach thesis, which covers this topic in detail.

Section 8.1 shows the geometric relationship between differential projected solid angle and differential area (equation (8.2)).

Section 8.2 uses this to convert between pdf wrt projected solid angle at x to pdf wrt area at x' (last equation in section 8.2).