I am trying to understand the exact lighting computation going on in cycles renderer. I've set up a test scene as follows:
- Cube whose corners are at [-1, -1, -1] and [1, 1, 1]
- Its material is set to [1, 1, 1] diffuse and [0, 0, 0] specular
- Lamp at [0, -3, 0] with no distance attenuation (light falloff set to constant)
- Lamp's strength is set to 10 with 0 as smooth value
- Camera at [0, -5, 0]
- Background light set to [0, 0, 0]
I've also disabled sRGB output (display device is set to None instead of sRGB). The exposure value is set to 0.
With these I am getting an image with cube's pixel value 65 at its very center (the region that receives light parallel to the surface normal). What can be the explanation of this?
I would expect something like 10 / (4 * pi). The reason of division by 4 * pi is that cycles defines point lights using power (in Watts). I also tried rendering in EXR format and it still doesn't produce the expected value.