| 主权项 |
1. A computer-implemented method for querying a database that comprises 3D modeled objects that represent mechanical parts, the method comprising:
providing a query that includes a likeness criterion relative to the value of a predetermined shape descriptor for an input 3D modeled object; returning, as results of the query, respective 3D modeled objects of the database, a respective 3D modeled object being returned based on an extent to which the value of the predetermined shape descriptor for the respective 3D modeled object respects the likeness criterion;wherein:
the 3D modeled objects of the database and the input 3D modeled object are each defined at least by a 3D mesh, the 3D mesh of a 3D modeled object having vertices and edges connecting the vertices, the vertices and the edges forming faces that represent the envelop of the mechanical part represented by the 3D modeled object, the value of the predetermined shape descriptor for a respective 3D modeled object includes a set of axis systems that are trihedral, the set of axis systems being in a bijective association with the set of pairs consisting of a respective vertex of the 3D mesh of the respective 3D modeled object and a respective face of the 3D mesh of the respective 3D modeled object, the axis of a respective axis system being oriented based on the directions, at the respective vertex, of the edges connected to the respective vertex, on a direction, at the respective vertex, normal to the envelop of the mechanical part represented by the 3D modeled object, and on an orientation of the face that corresponds to the outside of the mechanical part, the likeness of a first value of the predetermined shape descriptor relative to a second value of the predetermined shape descriptor increasingly depends on an extent to which the set of axis systems of the second value of the predetermined shape descriptor matches the set of axis systems of the first value of the predetermined shape descriptor modulo a same similarity transformation. |
