Evaluation of 3D Measurement Scanning Technologies

Since the technique of 3D data acquisition was developed in the 1960's, the areas of use have increased over time, and today there are 3D scanners for both consumer grade and industrial applications. One important application area is surface guided radiation therapy. By using 3D scanning technologies to position and monitor patients during the treatment period, the accuracy of the treatment can be increased in comparison to standard positioning methods such as tattoos and laser guides. This thesis aims to evaluate the performance of one 3D scanning system of active stereo type, and two of structured light type, along with one monocular depth estimation software. The evaluation focuses on the accuracy of the 3D models in terms of geometry and distance from the scanner. The study includes an in-house collection of 3D data together with data processing, analysis and model fitting. Three objects of varying geometrical complexity have been used to evaluate the scanners. The deviations from known or estimated reference values produced by the structured light scanners were smaller than those of the active stereo for all three objects. The analysis showed that errors obtained from one object cannot be directly translated to another, at least not without scaling. The depth estimation software needs further data processing to be used for analysis of the two more geometrically advanced objects. Overall, the results show that the deviations are small in comparison to the distance from the scanned object.