I'm increasingly posting simplified 3D building models on my websites using ThreeJS. I don't understand why ArchiCAD26, while exporting a simple cube model from the 3D window to an OBJ file, simultaneously exports so many materials that are not present in the model at all. Example results of exporting a regular mesh cube:
file.obj (model geometry - simple mesh cube): 1 usemtl (only ONE material !!!)
looks like a bug to me. When I start with a fresh new Archicad I got an OBJ surface folder with the exact 4 surfaces that I have assigned. Then l used a slab and another wall and deleted these objects and now I get these surfaces as well in the surface folder. I guess that Archicad exports all surface that have been used at some point in the project file. That should be reported to the support team.