How Do I Save An OBJ file alone with its .MTL (color information?)

[Kevin Liang]

I am having trouble exporting obj files along with its .mtl file. First I import a ply file, then I color by Filter --> Color Creation and Processing --> Colorize by Border Distance. The Color is saved in the vertex (Per Vertex), however when I save it as an OBJ file, no MTL accompanying it is present.

[Tim Ayres]

Vertex color data is saved in the obj file itself. The mtl file is only for UV mapped texture colors; if your model does not have any textures then no mtl file will be created.