The fundamental data structure underlying RAPID is the OBBTree, which is a hierarchy of oriented bounding boxes (a 3D analog to the "strip trees" of Ballard). The paper describing OBBTrees is given below. Please note that there are errors in the paper. A list of errata follow.

OBB-Tree: A Hierarchical Structure for Rapid Interference Detection, Stefan Gottschalk, Ming C. Lin, and Dinesh Manocha (27 pages PostScript) 493K, Technical report TR96-013, Department of Computer Science, University of North Carolina at Chapel Hill. Proc. of ACM SIGGRAPH '96.

- ERRATA: The equations for the "infinitely densely" sampled triangles in the second column of page 173 (of the SIGGRAPH '96 publication) are incorrect. Here are the correct equations, but notice that we are using the variable A for the area of a triangle, and the variable m denotes the centroid of a triangle (which are different usages from those in the paper).
- Pierre Terdimen has proposed efficiency enhancements to RAPID, improving on the speed and memory footprint.
- Stefan Gottschalk has posted a response to Pierre's comments.

**Geometric Algorithms for Modeling, Motion, and Animation**

*Last updated by gottscha@cs.unc.edu. Please send comments or questions to geom@cs.unc.edu.*