@Adrie_dV more or less we want to achieve the same thing as I am describing in my thread here. After discussing with Greg and with others what I’ve understood is that Radiance can calculate output values of different metrics (illuminance included) on a pixel by pixel basis, i.e. on the 2d image space. Thereafter how you choose to map these back to vertices/3d mesh depends on the user and different mapping solutions.
At the moment I am working on it so that I can create a pipeline which will kind of automatize the procedure if possible. I am new to Radiance so the learning curve for the moment is quite steep until I manage to get more comfortable with all the available tools. Whether it will work at the end, not quite sure but I am quite optimistic considering the words of Greg that others have done it in the past. Unfortunately though there are not that much of clear documentation/information regarding the steps to be followed.