thanks again for your advices.
-Why do you multiply by 1/6?
-Where is the light color?
Oh I forgot the lightColor in the formula, of course it has to be in there,
According to Andreas Kirsch and his Annotations paper http://blog.blackhc.net/wp-content/uploads/2010/07/lpv-annotations.pdf, the 1/6 came from the the approximated solid angle of one surfel of the texture viewed with a 90 degree field of view, this gives aus for the solid angle approximately:
4 Pi/6 *1/(rsmwidth*rsmheight), the 4 Pi, then is canceled because the equation to that point is:
outgoing flux of a rsm surfel= diffuse material Color * roh/4Pi * total flux*cos (Theta), with roh being the solid angle described before.
I saw other formulas for the rsm flux computation as well but this was good documented and makes sense to me, if there are other recommandations I would love to here them.
The functions in the volume are spherical harmonics that represent radiance (energy flowing through space) and what you need for rendering is irradiance (incoming radiance at a point). To do that you sample the spherical harmonics using the surface normal as sampling vector and a set of special coefficients where these coefficients represent the hemisphere above the point being processed, in particular they represent the cosine convolution of that hemisphere. The area of the pixel doesn't play an important role here and it can be ignored.
Oh ok that sounds like the way I do it at the moment, create spherical Basis functions in direction of the negative normal and do a dot product with the coeffients saved in the according volume cell. The point why I was thinking about changing this was that the crytek paper points out to use the haf cell size to convert intensity to incident radiance " However, since we store intensity we need to convert it into incident radiance and due to spatial discretization we assume that the distance between the cell’s center (where the intensity is assumed to be), and the surface to be lit is half the grid size s." (Cascaded Light Propagation Volumes for Real-Time Indirect Illumination from Kaplanyan and Dachsbacher) With grid size they mean cell size. And in a way I would like to somehow use the cellsize somewhere in the process because it feels wrong not do use this, but as said I think I do it in the way you recommend right now.
BTW, please forgive my honesty but I think you're paying too much attention to the theoretical details and forgetting that the whole technique is a huge hack so mathematical correctness won't bring you the benefits you expect.
You are welcome and I really appreciate your hints and the way why I am thinking about the theory is because I want to understand it completely if I impelement it then is another question. I have already ways to tune with some factors during runtime and you are right they can make the scene visually better.
Have you any thoughts about the gbuffer occlusion injection? I do it with the squared distance to the camera and one factor I can set myself during runtime at the moment.
Thanks a lot