dc.description.abstract | Reverse engineering is a process of reconstructing a 3D virtual model from digitalizating an existing physical part, in which scanned data are acquired by a scanning device. A triangular mesh, composed of scanned data and topology information, is built then. Owning to device limitation and improper operation, some mesh problems might occur frequently and it is hard to obtain key curves and surfaces, used to reconstruct 3D CAD model, from the triangular mesh. Hence, this study aims to solve mesh problems, focusing on two important mesh processes:quality repair and feature tracking.
As for quality repair, this study develops a hole-filling method that automatically chooses the specific algorithm depending on the type of the hole. While the hole is small and simple, the efficiency-oriented algorithm is implemented. While the hole is huge and complicate, the quality-oriented algorithm can be implemented to acquire a smooth filled mesh that has good connectivity with the original mesh. Moreover, this study analyses numerous real scanned data and induct ten type mesh problems that affect mesh quality. To solve these mesh problems, this study proposes a comprehensive method. As for feature tracking, this study proposes a new semi-automatic feature detection algorithm using one seed point to provide precise searching for feature points. A search graph, containing nodes and its access relationship, provides the candidate points for the search process. A bi-directional, multi-segment search strategy is then proposed to determine the optimized feature path. The cost function is essentially composed of four terms. The first two terms are employed to track the nodes of similar maximum curvatures and directions of minimum curvature variation, while the last two terms are employed to stabilize the path. In sum, this study demonstrates the feasibility of this approach through a great number of testing trials.
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