Just working on photorealistic archViz, emissive materials have been a great help, but now would like to have more control about how much light they cast, not just based on my experience and art decision but on real specifications for the project.
Is there some relation in between 1 emissive material with intensity 1, is emitting 1 unit of light per cm2?
So if I boost the emissive 10 and I have intensity 5 i will get 50 units per cm2
Actually one of the problems that move me to use emissive material for lighting is that IES profiles do not work very well with rectangle lights (as the spotlight you lose the part of the information) or point light with length, where you actually get the IES applied from a center point, not a centerline. And of course the freedom to use in any shape.
But there is no control about how much, more than try & error and experience, but in this case, we will like to check if the designed light (on construction drawings) actually is right or not before the build.
The Light propagation volume as a dynamic system does some simplifications, to get a great effect in the trade of precision, so I will keep on static lighting.