The official Blender documentation provides a method to get the “Specular” value for the PBR-material reflections if the “IOR” value is known. To get the “Specular” value from the “IOR” value, we can use the following equation:
It is not difficult to create it with nodes:
To do this, add five “Math” nodes
shift + a – Converter – Math
and connect them as follows:
It should be noted that this equation is valid only for dielectric materials. For its proper work you must specify real IOR values, for example:
- water IOR = 1.33
- glass IOR = 1.50
- diamond IOR = 2.417
The node group “IOR to Specular reflection” can be downloaded from the BIS library:
