Methods and apparatuses can include generating computer 3D models of an object, by registering two or more scans of physical models of an object. The scans may be 3D scans registered by a curve-based registration process. A method can include generating a 3D model of a portion of a patient's oral anatomy that can be used in dental restoration design. Scanning workflows can include scanning physical models of an object to obtain a 3D model. A scanner can scan physical models of a patient's dentition to obtain scans used to generate a 3D model of a patient's dentition.