Ok, I work with Light Propagation Volumes at the moment, there are some things in the theory I dont know how to implement them correct.
This is from http://blog.blackhc.net/wp-content/uploads/2010/07/lpv-annotations.pdf
Lets start with the Reflective Shadow Map and the flux which should be stored in it.
I have a "directional" light source with an arbitrary light Color, a total incoming flux, diffuse material color , width and height of the reflective shadow map texture and an angle theta between the light direction and the normal.
My flux for this surfel of the map then should be:
fluxOut=diffuse material Color * 1/6 *1/(rsmWidth*rsmHeight)* total flux*cos (theta)
The Injection of light then is, just take the flux and divide it by Pi. for every surfel of the reflective shadow map and add up the values in the appropriate cell of the light volume. Then you have an intensity function in each cell .
Ok now we have the occlusion injection or in my case 2, one from the reflective shadow map and one from the gbuffer.
In the paper above I believe there is onle the injection from the refelective shadow map described, the formula there is
surfelArea= 4.0*distance*distance/(rsmWidth*rsmHeight), distance means the distance from the light source to the object this is clear since the area will grow with the square of the distance but where does the 4 came from??
And for the GBuffer injection I also think about what is the right way to do it. The difference is that one is a orthographic projection and one a perspective (Gbuffer).
Propagation is clear to me,
I compute which amount of flux came from which face of the 6 neighbour cells and reproject this amount and divide it by Pi to get an intensity.
This is just the short version but as I said this is clear to me.
Now I have the volume with the propagated light and now I want to use it for rendering the indirect light into the scene.
Question here is, I have intenstity(I) functions in my volumes and what I need for rendering is the radiance(L).
The function is: L= I/A, so I need either the area of the Fragment or whatever I am just rendering or i can use the intensity to compute the irradiance E: E=I/r². The LPV paper from crytek says that the are using half the cellsize as r so then I can came up with the irradiance but what I have then to do? I mean L=E/w (w the solid angle, but what is the solid angle in that case)?
If someone has some explanations I would appreciate it, or if some one has questions regarding the described theory feel free to ask.