Coherent object selection in pattern hierarchies

We present an approach for encoding and specifying coherent selections in pattern hierarchies. Hierarchies of patterns of features or other modeling entities are used in architectural and mechanical CAD to eliminate laborious repetitions from the design process. Yet, often a subset or selection of the repeated occurrences in the model must be edited. Specifying a desired selection of occurrences in a hierarchy of patterns is often tedious (involving repetitive steps) or difficult (requiring interaction with an abstract representation of the hierarchy graph). Our approach addresses these two drawbacks simultaneously, offering an effective and intuitive solution which requires only two mouse-clicks to specify any one of a wide range of selections. It has a concise representation and is simple to compute. We discuss a novel representation of a selection, a technology that makes it possible to use only two mouse-clicks for each selection, and the persistence of these selections when the pattern hierarchy is edited.