Glossy shader
Posted: Thu Oct 20, 2016 6:16 pm
Hello everyone,
I'm doing some test with octane demo and I have some questions about the glossy shader, I don't understand the logic behind the way it behaves, It seems to me that it's wrong, maybe you can help me:
- if I try to build a simple colored metal using the built-in IOR I get something that is very inconsistent, the diffuse is always there even when is set to 0. It's like the specular component is multiplied over the diffuse, and not driven by the fresnel effect. The result is something that is too dark or too washed out. Either way the effect doesn't look correct or energy conserved.
- if I set the IOR 1.0 I expect that the shaders behaves like a diffuse material, but it's not. I guess because the shader replace the fresnel effect with the specular values, which is a bit strange anyway because again it takes into account the diffuse. But in this case the metal looks more correct, it's not much darkened, why is that?
- film (coating?): isn't the film a thin layer on top of the material? It has its own IOR but it doesn't work if the material behind has no specular, which it doesn't make much sense to me. Is that correct?
- the roughness power very aggressive in the first from 0 to 50%, like in Lw default shaders. Is there a way to use something like the POW node to remodulate the effect of the roughness? It behaves very badly with textures with roughness variation imho.
- also on roughness: the glossy shader at 100% roughness and high specular is still something very metallic, which is obviously wrong. It look like a bit tricky to solve this with the standard octane nodes. Any suggestions?
Thank you for the help!
I'm doing some test with octane demo and I have some questions about the glossy shader, I don't understand the logic behind the way it behaves, It seems to me that it's wrong, maybe you can help me:
- if I try to build a simple colored metal using the built-in IOR I get something that is very inconsistent, the diffuse is always there even when is set to 0. It's like the specular component is multiplied over the diffuse, and not driven by the fresnel effect. The result is something that is too dark or too washed out. Either way the effect doesn't look correct or energy conserved.
- if I set the IOR 1.0 I expect that the shaders behaves like a diffuse material, but it's not. I guess because the shader replace the fresnel effect with the specular values, which is a bit strange anyway because again it takes into account the diffuse. But in this case the metal looks more correct, it's not much darkened, why is that?
- film (coating?): isn't the film a thin layer on top of the material? It has its own IOR but it doesn't work if the material behind has no specular, which it doesn't make much sense to me. Is that correct?
- the roughness power very aggressive in the first from 0 to 50%, like in Lw default shaders. Is there a way to use something like the POW node to remodulate the effect of the roughness? It behaves very badly with textures with roughness variation imho.
- also on roughness: the glossy shader at 100% roughness and high specular is still something very metallic, which is obviously wrong. It look like a bit tricky to solve this with the standard octane nodes. Any suggestions?
Thank you for the help!