  We propose Point2Cyl, a supervised network transforming a raw 3D point cloud
to a set of extrusion cylinders. Reverse engineering from a raw geometry to a
CAD model is an essential task to enable manipulation of the 3D data in shape
editing software and thus expand their usages in many downstream applications.
Particularly, the form of CAD models having a sequence of extrusion cylinders
-- a 2D sketch plus an extrusion axis and range -- and their boolean
combinations is not only widely used in the CAD community/software but also has
great expressivity of shapes, compared to having limited types of primitives
(e.g., planes, spheres, and cylinders). In this work, we introduce a neural
network that solves the extrusion cylinder decomposition problem in a
geometry-grounded way by first learning underlying geometric proxies.
Precisely, our approach first predicts per-point segmentation, base/barrel
labels and normals, then estimates for the underlying extrusion parameters in
differentiable and closed-form formulations. Our experiments show that our
approach demonstrates the best performance on two recent CAD datasets, Fusion
Gallery and DeepCAD, and we further showcase our approach on reverse
engineering and editing.
