鞋楦的外觀造型可說是一個自由曲面(Free form surface)的典型代表，基本尺寸相當少，早期在母楦設計完成之後，若要大量複製成鞋楦，只有仰賴同步拷貝的方式進行仿削。而在CAD/CAM系統導入之後，始可應用逆向工程技術，以實物重建出CAD模型，再進一步做設計、加工或分析的工作。 有鑑於目前國內在鞋楦CAD模型重建上所使用的軟體，大多為泛用型之逆向工程軟體，尚未將其對鞋楦的效益提到最高。本研究便是針對鞋楦之專業領域，有系統地整合多項逆向工程技術：包括(1)對掃描網格資料的直線切層、徑向切層、點資料排序、點資料取樣、邊界萃取、邊界分割等。(2)應用多項曲線、曲面的重建功能並將其使用介面快速化與方便化。(3)具自動判斷的曲面縫合。經由對鞋楦的一系列處理，最後針對建構完整的CAD模型在重建程序上、重建效率上、曲面品質上與功能完整性上作一個整體性的討論，並以商用型之逆向工程軟體Surfacer進行客觀性的比較。 The geometric model of a shoe last is a typically composed of free form surfaces rather than basic geometric shapes. In the early, if the mother-last was completed and was used to produce large number of shoe lasts, the only method that could be used was mechanical mockup. After the CAD/CAM system is widely used, the Reverse Engineering Technology can be applied to reconstruction the CAD model of the parts and hence to the purpose of design, manufacturing or analysis. However, the efficiency of establishing CAD model for shoe last is not good enough. Due to the fact that most reverse engineering software used for CAD model reconstruction belong to general-purpose type, this research is intended to develop domain-based reverse engineering technology for shoe last. The proposed strategy include (1) straight and rotate slicing of STL format parts, sorting, sampling, edge detection and segmentation, (2) specific curve and surface reconstruction algorithm that is more convenience in the user interface, (3) surface merge algorithm enhancing automatic detection of the common surface edges. A series of processes for the CAD model reconstruction of shoe last are proposed. The propose results are compared with those obtained by means of commercial software – Surfacer in terms of reconstruction procedure, reconstruction efficiency, quality of surface and function completeness of the CAD model of the shoe last.
