Is it possible in the context of karma material builder to read a string attribute on a prim, and use this to reference an image for the parameter filename of mtlximage ? When I plug usdprimvar in file, I have:

Error Input storage type (uniform/varying) does not match input 'file'.


The problem I am trying to solve is this: I have a FBX file in SOP context; I am rendering in Karma. I am looking for a way to generate a texture that references various information that are stored in a dictionary attribute on each primitive. When imported in SOP, there is a shop_materialpath that points to a generated principledShader in fbxcharacterimport/matnet.

Can you suggest a workflow to translate the textures generated by FBX Character Import ?