I'm working on a kind of markerless AR application, which allows user to load its own 3ds objects into the application. And after that he should be able to move new-added object around, with regards to the other objects on the screen. Thus i should somehow implement collision-detection for an object which dimensions are unknown to me. What is the best way to do it?

For now the only thoughts i have is to first get object's mesh, then get bounding box and then on this basis construct ellipsoid to use in collision-detection. Is this the only way, or i missed something and now doing overcomplicated things?

The best (and for now unreachable) outcome would be if i can place 2 objects one right close to another, without any buggy intersections in between.