逆向工程為ㄧ種由實體模型的三維量測資料重建CAD模型之技術，其中點資料處理是整個逆向工程的第一步，也是最重要的ㄧ環。本研究的主要目的為針對由簡單二次曲面如平面、圓柱與圓錐等組成之實體的三角網格資料，發展手動與自動之特徵分離的機制，以減少分離資料的時間並能清楚掌握模型的幾何形狀。在發展相關機制前，需先探討特徵分離的基本流程包括特徵值的計算、設定閥值與限制條件以及區域成長，再透過不同機制達到簡單二次曲面分離的目的。 本研究處理的問題包含︰特徵分離基本流程、簡單二次曲面的判斷與再成長、手動點選分離機制與平面自動化分離。由特徵分離流程建立初步分離資料，再根據簡單二次曲面的判斷重新成長以獲得更完整且精確的資料，另外透過點選分離幫助使用者只對有興趣之區域作處理以提高效率。而自動化分離將以平面為例，在滿足誤差的前提下，一次大量分離相同形式的曲面以供後續建構需要。 Reverse engineering is a technique to reconstruct the CAD model from the three-dimensional measured points of a physical object. Segmentation of the digitized points is the first step in reverse engineering and is most important. In order to efficiently and accurately handle the digitized points, various segmentation algorithms should be provided. The objective of the study is to develop manual and automatic feature segmentation technique for triangular meshes from objects composed of simple surface such as plane, cylinder and cone etc. Before the development of the proposed algorithm, we first analyze the basic procedure of feature segmentation, including the characteristic values, threshold, constraint conditions and region growing. We then develop algorithms to accomplish the segmentation of quadratic features such as plane, cylinder, cone and sphere. The proposed method deals with the problems such as the basic procedure for segmentation, the judgment and the growing of the meshes for quadratic surfaces, manual segmentation and automatic planar segmentation. A procedure is implemented for initial recognition of the meshes belonging to the target feature. A meshes growing procedure is then implemented to find out all meshes belonging to the same feature. The manual segmentation process can help the users to find out each quadratic feature precisely. An automatic segmentation. Several examples are presented also to illustrate the entire process and to demonstrate the feasibility of the proposed method.
