The Essential Thinking Of Roughness And Anisotropy (2)
As a leading cloud rendering service provider, also a Redshift render farm, Fox Renderfarm published an article about “The Essential Thinking Of Roughness And Anisotropy (1)” last week. However, If you follow the view, you will find that you don't need the roughness parameter at all. The rougher the reflection, the better the texture with a higher bump strength is solved, let’s continue to discuss the roughness and anisotropy.
In theory, this statement is correct, and it is also very physical and in line with people's real life experience. But this kind of practice of using roughness to make roughness, there is a professional word to describe him, everyone who plays rendering should be familiar with it - brute force.
The reason is the same. This way, when you render GI, use the brute force algorithm to mean that the microstructure you express may be very accurate, but the rendering speed is extremely slow. 
maxAA = 4 
maxAA = 117 
maxAA = 1024 
maxAA = 8192
As can be seen from this set of graphs, when the roughness parameter is used to adjust the reflection roughness, there is no noise at very low sampling. But with bump control, very high sampling is required to effectively reduce noise. And even if the sample is given to the system with a maximum value of 8192 (the pictures are rendered using the Redshift renderer, the sample unit of rs is the square of the value of the sample equivalent to subdivs, where 8192samples is equivalent to about 90 of the subdivs; In addition, using maxAA to improve quality rather than using lighting samples is because the noise is not caused by insufficient light sampling, but the texture is very fine and must be super-photocamera to sample, and still see obvious noise.
That is to say, this idea is only theoretically correct, but it is a big mistake in production and industrial processes.
Then the roughness parameter was introduced to solve the problem discussed above.
Now please follow the best CPU&GPU render farm and cloud rendering services provider to our next part: The Essential Thinking Of Roughness And Anisotropy (3).
