When setting up materials for StemCell there are some general setting that must always be used. These settings are necessary to maximize consistency and portability to other renderers.
- Highlight Glossiness must remain locked so that Reflection Glossiness is the only one affecting the render.
- Use Fresnel must always be on in order to achieve more realistic reflections.
- Set IOR value for material within dielectric or metallic range for intended material using the same texture set. If multiple IORs of the same type, only dielectric or only metallic, are represented then set the IOR to the average of the IORs. The value difference between same material types is minimal in the render.
IOR values can also be set on the Refraction IOR settings as long as Lock Fresnel IOR to Refraction IOR is checked on.
BRDF type must always be set to GGX
Set all map contribution Amount slots to 1.0
Texture Map Settings
- Load _Diffuse map with matching material name to Diffuse Color slot
- Load _Specular map with matching material name to Reflection Color slot
- Load _Glossiness map with matching material name to Reflection Glossiness slot
Under Bump and Normal mapping, set Map Type to “Normal map in tangent space”. Load _GL_Normal map with matching material name into Map slot of Bump and Normal mapping.
Glossiness and Normal map are linear maps and must have their Color Profile set to Linear sRGB. Make sure Texture input Gamma is on for VRay in your attributes menu. Set Color Space in Extra Vray Attributes to Linear.
Diffuse and Specular map are sRGB maps and must have their Color Profile set to sRGB. Make sure Texture input Gamma is on for VRay in your attributes menu. Set Color Space in Extra Vray Attributes to Gamma.
Filter Type set to Off so the texture maps details do not get blurred
Additional Texture Maps
Depending on your model, you may have additional texture maps like Opacity or Emissive maps. These maps follow the same rules as the core required maps.
- Load _Opacity map with matching material name to Opacity map slot
- Load _Emissive map with matching material name to Self-illum map slot
What if my texture map set has multiple material types?
There are some situations where a material may require a dielectric and metallic materials on the same surface. See When to use Blend Materials for more information on these situations.
When an individual dielectric or metallic material can not be separated by object, that is the only time a blend material needs to be used. The Blend material is used to combine the 2 different IORs for dielectrics and metals. This way one material applied to the single object represents both surface types. A dielectric version of the material is created as Material 1 using correct low IOR value. A copy of that material is made for the metallic version as Material 2 with correct high IOR. The Metallic map is used as the Mask.