Recovering primitives in 3D CAD meshes

In an industrial context, recovering a continuous model is necessary to make modifications or to exchange data with a format including continuous representation of objects like STEP. But for many reasons, the initial continuous object can be lost after a display or an exchange with a discretized format. The mesh can also be deformed after a numerical computation. It is then important to have a method to create a new continuous model of the object from a mesh. In case of CAD object, the first step is to detect simple primitives like: plane, sphere, cone and cylinder from a 3D CAD mesh. This paper is focused on this step. This method of detection use curvature features to recover each primitive type. Segmentation is based on the curvature feature computed for each vertex. It permits to extract sub-meshes. Each one corresponds to a primitive. Parameters of these primitives are found with a fitting process according to the curvature features.