幾何模型最佳投影視角分析

電腦輔助設計與製造(CAD/CAM)技術經過多年的發展已經非常的普遍，但是隨著幾何模型資料量的快速累積，若能將模型最佳視角之投影視圖儲存，配合查詢者描繪(Sketch)輪廓圖形的方式進行資料比對，提供資料庫的查詢或取出，將有效於整個自動化的推動。本論文以STL資料格式所描述的物體為對象，先從三角網格模型中所包含頂點和法向量的資料，建立模型之幾何資料結構；接著利用資料結構訂出一個用來選擇起始視角之算式；由起始視角中所見的面進行加權；再以調整後的視角與其他視角間搜尋，然後調整投影面積得到最終視角之投影視圖；最後旋轉z軸，使得模型在視覺上能具有穩定的感覺。在本論文中，提出一個計算視角品質之觀測值，用來判斷模型經由旋轉之後，其投影視圖是否有比較好，觀測值主要考慮因素為頂點、面、邊與面積。雖然還無法針對含有圓孔、圓柱、圓角及橢圓等的模型找出適合的策略得到最佳視角，但本研究之方法對於多面體之模型都能找到不錯的投影視圖。

關鍵字

最佳視角；觀測值

並列摘要

Computer Aided Design and Manufacture (CAD/CAM) technology has been already develop for many years, with the fast accumulation of the model data base of geometry, if it could store the projection view of the best viewpoint of model ,and subsequently cooperate with the searcher that use the way of sketch contour to proceed the data comparison ,and it could supply to look up or take out of database, it will effect automation impetus. In our research, it used STL format to sketch our model, first it used vertex and normal vector of STL data to set up the geometry data structure of the model, subsequently utilize structure of STL data choosing the initial viewpoint of formula；Starting plus weighing the initial viewpoint of face seen ,and then search another viewpoint by after adjusting viewpoint ,then adjust the projection view that the projected area got the final viewpoint；Finally rotate Z-axis, it make the model can have steady feelings on the vision. In our research, it is provided a observed value of calculating viewpoint quality to determine the models via rotating that the projection view becomes better or not. The main consideration of observed value is vertex, face, edge and projected area. Though it still unable to find out the suitable tactics and to get the best viewpoint about the model of hole, cylinder, round angle and oval etc. But in our research, if we used STL method, it could find the good projection view for the model of the polyhedron.

並列關鍵字

The best viewpoint ； observed value

參考文獻

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[4] N.A. Massios and R.B. Fisher, “A best next view selection algorithm incorporating a quality criterion.” Proc.of the Britsh Machine Vision Conference, 1998.

[5] Lambert Wixson,“Viewpoint Selection for Visual Search.” IEEE Computer Society Conference on Computer Vision and Pattern Recognition, pages 800-805, June 1994.

[6] C.I. Connolly,“The Determination of Next Best Views.”IEEE International Conference on Robotics and Automation., pages 432-435, Mar 1985.

[8] K. Jonnalagadda, R. Lumia, G. Starr, J. Wood, “Viewpoint Selection for Object Reconstruction Using Only Local Geometric Features.” IEEE International Conference on Robotics and Automation, vol 2, pages 2116-2122, Sept. 2003.

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幾何模型最佳投影視角分析

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