displacement spreading to other Material ID

[fraggle]

Hello,
I'm trying to applied a displacement map to a multi material ID.
The displacement map spread outside and create some deformation on the other ID material.
Is there a way to avoid it?

Thanks

[king_max]

The surface is a single poly/mesh? Either detach the "button" to a separate element, or create a displacement map that covers the whole object with black areas where you don't want the displacement.

[fraggle]

yes single polymesh.
Thanks for the tips regarding the black area. I will try it.
Sounds like a bug in fact because the ID material should not disturb other material ID normally.

[king_max]

It's not a bug. If you have a plane with a displacement map that affects only part of the polygons, at render time the mesh gets subdivided/tessellated in that part. As a result the remaining parts where the flat and displaced areas meets gets "distorted" to accommodate the new vertex count/position of the tessellated area. See the attached example.