3D Modeling by Scanning Physical Modifications

3D shape design tends to be a long and tedious process, with the design of a detailed 3D part usually requiring multiple revisions. Fabricating physical prototypes using low cost 3D fabrication technologies at intermediate stages of the design process is now a common practice, which helps the designer discover errors, and to incrementally refine the design. Most often, implementing the required changes directly in the computer model, within the 3D modeling software, is more difficult and time consuming than modifying the physical model directly using hand cutting, caving and sculpting tools, power tools, or machine tools. When one of the two models is modified, the changes need to be transferred to the other model, a process we refer to as synchronization. Changes made to the computer model can be transferred to the physical model by 3d printing a new physical model. In this paper, we address the problem of synchronizing the computer model to changes made in the physical model by 3D scanning the modified physical model, automatically detecting the changes, and updating the computer model. The proposed process comprises algorithms to: 1) register each 3D scan with a previous 3D scan and/or with the 3D representation used by the 3D modeling software, 2) detect the changes (subtractive and/or additive), and 3) perform the changes on the 3D computer model.