I am wondering if I missed out something about the application of the BSDF and aBSDF models in Radiance. I have a photometric BSDF that was generated from measurements by pabopto2bsdf, and a colour measurement (D65/2° XYZ and Radiance RGB). Now I would like to add the colour information to my existing BSDF model, knowing that this is a simplification since the colour probably is a function of directions.
I know that I can add a (coloured) diffuse reflection component by three real numbers in the BSDF definition. However, wouldn’t this effectively increase the reflectance unless I can subtract this component from the reflection returned by the tabular model? Or is this done internally? I was going through m_bsdf.c, but did not find the answer that is probably hidden there.
Another way, assuming that the colour of highlights is modulated by the surface, would be to multiply the BSDF by the normalised colour values. This, however, is not possible since colorfunc etc. only affect the diffuse component.
Finally, one might - under the same assumption of coloured high-lights - regenerate the BSDF (in my case from measurements) scaling the photometric values with the XYZ. Is this reasonable?