4% reflectivity for dielectrics

[khaled.pamir]

Hi there

Is the Arnold 5 shader making the assumption that all dielectrics have a 4% reflectivity/specular value similar to how substance painter works with its metal/rough workflow?

With this workflow we would leave the spec color at 1 and control overall reflectivity with the ior.

So as an example if we had a plastic material with and a layer of dirt on there as well, we would leave the specular colour at 1 for both materials, but they would have different IOR values.

Or should we be assigning spec values based on the various materials we have on our objects in addition to adjusting the IOR?

For example if I have the same plastic and the same dirt textures, my spec value for the plastic would be around .5 and my dirt would have a spec value of .2 and the plastic and dirt would have appropriate IOR values as well.

Any clarification would be amazingly helpful!

Thanks.