Geometric sketch constraint solving with user feedback

Bridget M. Dixon, John F. Dannenhoffer

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Modern CAD systems rely on two-dimensional sketches as the basis for the creation of most three-dimensional geometry. These sketches consist of qualitative shape information as well as a series of constraints to quantify the exact size and shape of the various segments, arcs, and splines that comprise the sketch. Example constraints include overall lengths, symmetries, parallel and/or perpendicular segments, and arc radii. For a given sketch, there are many sets of constraints that unambiguously define the shape. Unfortunately, sometimes a user prescribes a set of constraints that do not allow the sketch to be solved. Providing feedback to the user as to how to change the constraint definitions to remedy the problem is still a largely unsolved problem. Herein is described a series of techniques for helping a user diagnose sketch problems and provide to the user a series of options that will cause the sketch to be properly solved. The techniques are incorporated in theOpenCSMsolid modeling system. Several sample configurations that use these techniques are shown, with a description of the user interaction that the system provides.

Original languageEnglish (US)
Pages (from-to)316-325
Number of pages10
JournalJournal of Aerospace Information Systems
Issue number5
StatePublished - May 2014

ASJC Scopus subject areas

  • Aerospace Engineering
  • Computer Science Applications
  • Electrical and Electronic Engineering


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