Geometric Primitives

In many fields of design, including information systems, a “primitive” is the building block from which more complex forms are constructed. Thus, in a geographic information system (GIS), there are a small number of geometric forms that serve as the geometric basis on which a richer system can be constructed. This entry concentrates on the two-dimensional forms that form the basis of the raster and vector GIS software. It also covers some of the primitives developed for surfaces and three-dimensional forms. Arguments over geometric primitives played an important role in the emergence of this technology, and thus history is inseparable from the topic.

Geographic information is distinctive in a number of ways, but the most obvious is that it must represent spatial entities and their relationships. ...