The lighting of a scene primarily used diffusion and reflection effects.
We have seen the basic shader using Cycles, entitled "spread”, based on the model of Lambert or of Oren-Nayar, based on the value that is used for the parameter "Roughness" ( 0 = Lambertian). This calculation model simulates the dispersion or diffusion of light on the material, but does not consider the effects of specular reflection that are associated with the model called “Glossy”.
A mirror image is generated by reflection the light an specular surface, where the incident rays are reflected with angle equal to incidence (both taken with respect to the perpendicular to the plane at that point).(W)
There are three different shaders on the type “Glossy”
- Beckmann: Default method for defining the amount of light reflected from a surface. ( 0 for pure mirror, 1 reflects nothing)
- GGX: Also to determine the degree of reflection. Provides intense shine.
- Sharp: Pure Mirror.
The degree of reflection from the surface is controlled by the parameter Roughness, as shown in the following images that shows the value used.
Consider an example with a simple scene consisting of three planes, three spheres and a cube
Beckman model with specular maximum results in the following image:
The model adds shine GGX resulting light spot used (spotlight)
Sharp model (espejo) does not differ substantially from Beckmann to the value of “Roughness” = 0, but provides a greater amount of light (more light)
Later we will see that in addition to the simulation of mirrors, shaders mixed with other materials can contribute to the feeling of having polished and shiny surfaces, as in the case of metals, marble etc.