An Analysis of Geometric Modeling in Database Systems

The data-modeling and computational requirements for integrated computer aided manufacturing (CAM) databases are analyzed, and the most common representation schemes for modeling solid geometric objects in a computer are described. The primitive instancing model, the boundary representation, and the constructive solid geometry model are presented from the viewpoint of database representation. Depending on the representation scheme, one can apply geometric transformations to the stored geometric objects. The standard transformations, scaling, translation, and rotation, are outlined with respect to the data structure aspects. Some of the more recent developments in the area of engineering databases with regard to supporting these representation schemes are then explored, and a classification scheme for technical database management systems is presented that distinguishes the systems according to their level of object orientation: structural or behavioral object orientation. First, several systems that are extensions to the relational model are surveyed, then the functional data model DAPLEX, the nonnormalized relational model NF², and the database system R²D² that provides abstract data types in the NF² model are described.