映射函數三維空間影像量測技術研究

Three Dimensional Coordinate Measurement Utilizing Space Mapping Function

林高輝(Kao-Hui Lin)

指導教授 ： 章明

中原大學/工學院/機械工程研究所/博士(2002年)

https://doi.org/10.6840/cycu200200118

摘要

本研究發展出一種新穎的三維座標非接觸量測方法及其校正技術，其主要演算法係直接利用物體的三維座標與數位影像的映射關係，使用最小平方誤差擬合技術來完成簡單且有效率的校正程序。具體作法係利用在量測空間中已知座標的一系列特徵點形成一組校正網格，經透視投影成像在雙CCD攝影機中，得到二組對應2D 平面特徵點影像座標，使用高次多項式函數擬合成為三維的對映函數轉換關係，即完成了量測系統的校正程序，而量測時則將CCD攝影機影像中欲求點的像素位置值代入對映函數中即可得到三維之空間位置。此三維函數對映的方法相對於一般的三角量測法而言，主要優點在不需校準三角量測中的量測參數，故量測元件CCD攝影機及雷射光源的位置安裝不需要非常精確，且校正時可利用三軸移動平台進行校正，適合於量測隨機校正。
在實測的結果中，無論是單線雷射掃描量測或是旋轉量測，在本研究採用之量測系統所設定的80mm*30mm*48mm量測空間中，其量測精度在0.04mm以下，重複度為0.01mm，顯示本演算法有潛力在非接觸座標量測系統中成為高速、高精度的位置量測技術。

關鍵字

三維座標量測 ； 映射函數 ； 最小平方多項式 ； 立體視覺法

並列摘要

This paper proposes a novel measuring methodology and calibration method for 3-D coordinate laser non-contact measurement. This algorithm introduces variables that relate the output digital image directly to the viewed 3-D object. A simple and efficient calibration procedure is achieved using the least-squares technique. It takes advantage of a 2-D coordinate mapping relation along with dual CCD cameras and a 3-D calibration grid consisting of a series of characteristic points with known coordinates in real space. The space coordinates of these characteristic points are compared to their image coordinates in the CCDs. A 3-D mapping function between the actual space and its image planes in the dual CCD cameras is then constructed. The relationship between the two is determined accordingly and can be applied to extract 3-D information from a tested object sitting in a specific space with satisfactory accuracy.
Current experimental results show that the measurement accuracy is under 0.04 mm with a repeatability of 0.01 mm in a bounded space of 80 mm×30 mm×48 mm weather by using the single laser translational scanning or rotating scanning technique. This result reveals that this measurement algorithm has the potential to be an effective positioning method for rapid and precise non-contact coordinate measuring systems.

並列關鍵字

3-D coordinate measurement ； least-squares polynomial ； stereo vision ； mapping function

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