p.137 Shading normal
The shading normal differs from the geometry normal. The shading normal has no physical meaning, therefore, this causes a trouble if we use it to compute physical energy. Indeed, if we use the bump mapping, then the energy computation for the geometry must be handled something special.
p.140 Figure 5.1
The light energy inside of refraction object should be scaled. I never think about that. Indeed, water (refraction object) makes incoming light more dense inside the water. This means energy is concentrated inside. Therefore, we need to consider this. But the usual case, when light goes into the refraction object, then energy concentration happens, also when light goes out from the same refraction object, the inverse effect happens and the energy is un-concentrated. Therefore, I never think about that. In this figure, the algorithm need the energy of inside the water, this effect should be considered. For example, if a camera is inside the water, there could be also a problem.
p.168 D3 and Equation 5.30
p.168's D3 and Equation 5.30 are not clear for me. If anybody knows that, please teach me.
2 months ago