<title>Constraint-based solid modeling with geometric features</title>

Abstract

Engineering design practice usually follows a design hierarchy. Constraints more or less reflect engineering requirements. But constraints are practically useful only when they are correctly embedded into design hierarchies. The concept of geometric features is introduced to serve the following purposes: to allow a designer to work with the conventional design hierarchy; to control the effect of constraints; and to decompose a complicated constraint based geometric modeling problem into simpler ones. Geometric features are constructed hierarchically. Although constraints are applied to low level geometric entities (points, lines, etc.), the impact on a design model is usually imposed on higher level features. In terms of constraints processing, each feature is viewed as an independent problem and its constraints are solved independently. All constraints in a design model are therefore solved hierarchically bottom up.