Intelligent Form Feature Interaction Management in a Cellular Modeling Scheme


Form features present a rather attractive building block in computer-aided design environments for a variety of applications, providing the embodiment of engineering semantics in specific part shape.
In this paper we address the issue of volume feature behaviour throughout interaction phenomena. First, the fundamental concept of form feature as expression of the morphology of a model, is presented. A description of the feature properties, attributes and general constraints that are relevant for our purpose is attempted. In order to develop sound validity conditions for the various classes of form features, feature definitional entities are also introduced. A comprehensive definition of interaction among features is given that encompasses both adjacent and intersecting features.
We use a structured cellular modeling scheme to capture both the morphology of features and the interactions among them. Within this framework, a thorough analysis of feature interactions is performed that explores the accessibility of feature definitional entities in order to assist feature-based model editing and validation.
Operations that create or modify features often interfere with pre-existing ones, producing unanticipated effects that can corrupt or, at least, modify desired feature semantics and/or morphology. On the other hand, valid features can be obtained that exhibit non-standard or disconnected topology as a result of interactions caused by such operations. Systematic management of feature interactions is explored in both cases, from an object-oriented point of view, encapsulating interaction detection methods in feature class definition. This approach is shown to be quite adequate to handle complex interactions among several features. Reasoning mechanisms may, thereafter, be required to handle each situation identified.

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