Is possible to add and assign a RGB color to a material and render it using Radiance and then visualize for example after a PITView simulation, via HDR? Or is only possible to set the light reflectance?
You can make colored RGB Radiance modifiers using any of the components that end in 3 under the HB-Radiance 1::Modifiers section.
If you use the HB Custom Sky component, you can also create colored skies as long as the ratio between direct and diffuse radiation falls within realistic ranges.