Model Simplification

STL and OBJ are two of the most common file formats used for tool and scene object 3D models. STL files describe only the surface geometry of a three-dimensional object, while OBJ files contain a three-dimensional object, including 3D coordinates, texture maps, polygonal faces, and other object information. Simply put, models in STL format can be seen as void, while models in OBJ formats can be seen as solid.

The model on the left is an STL file, and the one on the right is an OBJ file.

In collision detection, only the intersection on the surface of the object can be detected when a model in STL format is used; while both intersections on the surface and inside the object can be detected when a model in OBJ format is used.

This chapter covers the basic principle of collision detection when using 3D models in STL and OBJ formats and the method for simplifing the models.

• Basic Principle of Collision Detection
• STL Models Simplification
• OBJ Models Simplification