Abstract
A representation scheme is presented that is suitable for defining and operating form features. Five basic constituents, B-rep solid components, measure entities, size, location and constraints, are used to represent a single form feature. With these constituents, form features are defined structurally and procedurally. Parts are then represented by a higher-level structure, called a feature-dependency graph, in which feature-position operators link the form features. In the FDG model, dimensions are used to determine the size and locations of form features. This property makes the manipulation of form features more consistent with the designer's intent. A C++ implementation of the physical data structure according to the logical representation scheme is discussed. © 1993.