Combining Optical Scanning and X-Ray Computed Tomography Data for Modeling the Internal and External Geometries of Cultural Artifacts

Recording the internal and external shapes of an artifact separately using different digital technologies is inefficient from a data management perspective and limits comprehensive geometric analysis. Thus, in this study, mesh-based convergence modeling was performed to merge optical scanning and X-ray computed tomography (CT) models of the replica of an artifact to obtain a single three-dimensional (3D) model. Optical scanning recorded the precise external surface of the object, and X-ray CT obtained the internal geometry. The X-ray CT model was aligned with the optical scanning model with high dimensional accuracy, and the registration accuracy was analyzed through root-mean-square (RMS) deviation visualization. The average RMS deviation of the replica was found to be 0.13 mm, less than the point spacing obtained using the optical scanning and X-ray CT models. Subsequently, the external surface shape of the X-ray CT model was removed, and this model was merged with the optical scanning model to acquire a complete 3D converged model. The volume of the converged model was 1.8% larger than that of the X-ray CT model due to the external geometry of the optical scanning model. The significance of this research is that the internal structure of the object, which cannot be modeled effectively using optical scanning alone, was determined using X-ray CT.