Interpreting the Engineer’s Sketch: A Picture is Worth a Thousand Constraints

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We describe a program called SketchIT that transforms a single sketch of a mechanical device into multiple families of new designs. To interpret a sketch the program first determines how the sketched device should have worked, then derives constraints on the geometry to ensure it works that way. The program is based on qualitative configuration space (qc-space), a novel representation that captures mechanical behavior while abstracting away the particular geometry used to depict this behavior. The program employs a paradigm of abstraction and resynthesis: it abstracts the initial sketch into qc-space then maps from qc-space to new geometries.