Glossary for Geospatial Science

CAD object:� A CAD object, in RVC format, like a vector object, is composed of coordinate data, but uses a different data structure.� A CAD object has a free-form topology, so it may be useful for applications that do not require an exact description of the relationships between the elements in the object.� CAD object topology does not reconcile things like line intersections, polygon overlap, and polygon islands.

A CAD object also allows for descriptions of geometric shapes.� For example, in a vector object, a circle is always stored as a polygon, and at a high enough magnification, the discrete point and line elements become visible.� By contrast, a CAD object stores a circle by its center point and radius.� Thus, at any magnification, it looks circular.

Since they have reduced topological constraints, CAD objects generally require less storage than their vector object counterparts.� [See also: element (CAD).]