What units are the values in an HDR texture?
Unless they use radiometric or photometric units wouldn't it be hard to combine HDR textures in one game?
In MAX photometric rendering I can specify light values in lumens or candelas ... but what is stored in the output texture?
Is there an important difference between illuminance and luminance?
I think an HDR light map (recording incident light on a surface) would need to store illuminance
whereas an HDR environment map or light probe would store luminance?