Modeling piecewise helix curves from 2D sketches

•Our method reconstructs a piecewise helix curve from a 2D sketch.•Helices are computed such that their projection matches the 2D curve.•An optimization is performed to minimize the tangent discontinuity of the helices.

We describe a method for a reconstructing piecewise helix curve from its 2D sketch. The system takes as input a hand-drawn polygonal curve and generates a piecewise helix curve such that its orthogonal projection matches the input curve. The first step is an algorithm to generate a set of helices such that their orthogonal projection approximates the input curve. This step is followed by a global optimization to minimize the tangent discontinuity of the junctions of the helices while keeping the fitting error small.