Use of Rational Numbers in the Design of Robust Geometric Primitives for Three Dimensional Spatial Database Systems Brian E. Weinrich and Markus Schneider   View Paper (PDF)   Return to Session 6: Virtual Reality and 3D Abstract A necessary step in the implementation of three-dimensional spatial data types for spatial database systems and GIS is the development of robust geometric primitives. The authors have previously shown the need for 3D spatial data types and rigorously defined them. In this paper, we propose a set of 3D geometric primitives that can be used to implement them robustly. We provide for their robustness by specifying them using rational numbers. In the discretization of space, the developers of two-di ... ©2006 Association for Computing Machinery