FlatFitFab: interactive modeling with planar sections

We present a comprehensive system to author planar section structures, common in art and engineering. A study on how planar section assemblies are imagined and drawn guide our design principles: planar sections are best drawn in-situ, with little foreshortening, orthogonal to intersecting planar sections, exhibiting regularities between planes and contours. We capture these principles with a novel drawing workflow where a single fluid user stroke specifies a 3D plane and its contour in relation to existing planar sections. Regularity is supported by defining a vocabulary of procedural operations for intersecting planar sections. We exploit planar structure properties to provide real-time visual feedback on physically simulated stresses, and geometric verification that the structure is stable, connected and can be assembled. This feedback is validated by real-world fabrication and testing. As evaluation, we report on over 50 subjects who all used our system with minimal instruction to create unique models.