# Assignment 4 Discussion

Don't hesitate to ask questions.

The first question says "L(phi, theta) = cos(theta) when theta > PI/2 and L(phi, theta) = 0 otherwise." Shouldn't this be for theta < PI/2, so that it's cosine-weighted sampling, which is more appropriate here? If theta > PI / 2, the arrangement doesn't make much sense - the luminance would be negative!