Hi, I have a mesh whose surface is made up of tesselating triangles. I would like to perform an integral over this surface of the form [itex]\int f(\Omega) R(\Omega) d\Omega [/itex] Where f is an arbitrary function and R is the radius at that point. I have a method implemented but it is not working correctly. I was wondering if anyone was aware of a better way. Basically my method is For each triangular face: Calculate the value of fR at each vertex of the face Calculate the average of these three values to find the average value of fR across the face. Multiply this value by the solid angle covered by the face. Sum up this result for all of the faces in the mesh. Unfortunately it doesn't seem to be working as I would have liked. Are there recommended ways of doing this kind of integration? (This is x-posted in another forum for those who may happend to see both) Thanks.