I am importing 3D scans in obj format into Blender to repaint textures and correct the UV map, e.g. remap faces that are mis-mapped, fill holes, merge vertices, etc. The issue I’m having is that although the obj only has a single material and texture, Blender creates extra materials (e.g. material_0.001, etc.) and copies of the texture (texture.png.001, texture.png.002, etc.), either during initial import or during subsequent editing. Sometimes when projecting faces they are mapped to the wrong texture, or when texture painting it is applied to the wrong texture as well. When exporting multiple materials are exported, even if I delete all of the extra materials from the object. I’ve searched and read the manual but haven’t found where this behavior is described.
How can I understand why Blender creates these new materials and textures, and can I make it stop? How can I tell what texture will be painted on when using texture paint? If I do want to use multiple material and textures with the same object, how can I make sure that the UV mapping (such as selecting faces and using “project from view”) is applied to the correct material and texture?
This is using Blender 2.74 on Windows 64 bit.
Thanks for any help!