[RESOLVED] MatGraph: Roughness

[cjwidd]

When you pass a roughness (texture) map into a material, black defines unitary dispersion and white defines stochastic dispersion. If you are 'layering' materials (e.g. metal base, plastic (paint) layer on top; curvature node to reveal base metal) the materials do not retain their original roughness value, they are overridden by the new texture map.

First, please correct me if this is not true. Second, if this *is* true, then how would it be possible to define two surfaces with unequal roughness values if their roughness values are always being replaced, rather than multiplied against? The only way would be to use separate textures, passed into a 'color adjust' node, and the modified slightly. This would seriously expand the MatGraph for complex materials.

[DriesV]

Firstly, re: "black defines unitary dispersion and white defines stochastic dispersion" ... I would rather say: black is roughness of 0 (shiny), white is roughness of 1 (rough). Dispersion is misleading in this context.

But yes, textures override number values of parameters.
And yes, if two materials should have different roughness, then two roughness textures should be used.

We have at some point discussed adding "Color to Number" functionality for "number" parameters directly in the material properties (without requiring to add an extra 'Color to Number' node in the Material Graph). This would provide a solution to your issue.
We have not developed this idea further though.

Dries

[cjwidd]

Right, I see what you mean about dispersion. Keyshot 7 has a lot of powerful features, but I think the MatGraph is a really fertile area for future development.

Thank you so much your advice

EDIT: regarding the functionality you alluded to: yes, I think there are several cases where utility nodes could be combined to reduce the number of connections necessary for achieving a specific effect.