Light levels?

Just to ask, is there any way to measure the level of light at any particular point in 3d space? Not sure what to call it, the luminosity, radiance…

I’m not sure if it’s possible in 3D space but you can check on renders the value of color on image.

For example max white value should be 1.0 but if the light source is too strong then it will be way over 1.0. This means that this area is overexposed.

Thnks arison. No, I want an object’s appearance to be affected via the light amount/level it intersects in space across it’s surface , I.e. something akin to implementing two shaders on one object via a light path…

Basically, no. Only at the shader stage can “rest of the scene” (environment, lights, shading of other objects etc) be accessed, and the result of these can only be plugged into mix/add shaders or material output. At least for now, you can’t route that info back into other parts of the material for use in such evaluations.

The only rendertime trick I can think of is using an empty at position of light, implementing original luminance, color, and falloff, and calculate shading manually. Get’s really complicated with many light sources.
Node example for using empty as light source.
Quick animtest using the above idea for “colored highlights”.

Very hacky and non userfriendly, but may be an interesting approach for something Cycles doesn’t allow us to do.

Thanks CarlG. That might help to achieve the look I’m going for… (not glow in the dark, but glow in the light effect - Thnks again.