I am trying to do some renders for a comparisons of a real world scenario with measurements of light sources (luminance, cd/m^2) and measurements towards the viewer (illuminance, lm/m^2) but having a bit of trouble interpreting of the actual values produced by LuxCoreRender in Blender. I have done the same renders using Cycles and there it is clear that pixel values are in the units of W/sr/m^2 (which I will the have to convert myself which is fine).
The confusion comes from the fact that when I place a white area light with cd/m2 set to e.g. 100, that is what the pixel value reads for both combined and emission layers, indicating that the output is in cd/m^2. But then the IRRADIANCE layer indicates that radiometric units are used (instead of illuminance which is expected for photometric values), which is part of the confusion.
But if I instead use the unit Power for a unit sphere and set the value to 100 W and lm/W=1, the output is approx. 1.38754 on all three RGB channels, where I would expect 100/(2*4*pi)= approx. 1.2679 cd/m^2 (and preferably a difference between the three channels due to different luminous efficacy, but since only one value can be supplied for all wavelengths I was not expecting a difference), so something is not quite adding up for me.
Changing lm/W to 10 yields pixel output of 13.87534, basically 10x the value of 1 lm/W so that is consistent and point towards pixel output being cd/m^2.
Maybe I am just tired and confusing myself, but would be great with some clarification/confirmation on all this
Thanks in advance!