Computer-automated shadow moiré method and applications for 3D surface profiling
thesisposted on 23.05.2021, 12:32 authored by Rui Zhao
Among numerous methods for 3D surface profiling, classic shadow moiré method has been kept as the most popular one due to its full-field feature and low cost. This thesis focuses on a computer-vision shadow moiré method with a scope to improve the measurement resolution, accuracy and efficiency. The computer automation is basically realized through the introduction of a phase-shifting technique that is incorporated with a new multi-grid least-square unwrapping algorithm. The method is enhanced by implementing a few additional image processing techniques. These techniques, when implemented, result in improved measurement accuracy and enable easy applications to irregularly shaped surfaces. The study also proposes a new, automated system calibration approach that is based on a real-time image subtraction. A data normalization process is studied to resolve possible confusions in the presentation of the original data. The verification test results show that the modified shadow moiré technique has achieved the initial goal, in that the measurement resolution now reaches a few percentage of the fringe sensititivity.