平行光柱投射式非接觸三次元量測技術研究

本文所探討之非接觸式量測，重點為三次元座標值之估算及平行光源之產生與運用。運用拋物面鏡反射平行光之光學特性及透視成像原理。以弧光燈為投射點光源，光源經針孔作用後，透過拋物面鏡反射，產生均勻的平行投射光柱。在投射光與被測物之間以LCD產生空間編碼圖案。投射光柱將空間編碼圖案依序的投射於被測物體表面，並同時運用取像感測器（ CCD）取像，進行空間編碼，以確定每一量測點之相對位置不致混淆。再將量測物件與取像感測器間之座標關係作適當的轉換，以獲得CCD之參數與所取影像之關係。當以適當的影像前處理程序，將所攝取之量測影像完成處理之後，即可得到被測物之3D對應平面（2D）座標值，據此，將2D座標之每一座標點與取像鏡心所構成之空間虛擬直線，及投射編碼圖案所形成之空間虛擬平面間將產生相對之唯一交點，因此量測物之三次元座標可順利產生。

關鍵字

三次元量測；逆向工程；影像處理；空間編碼

並列摘要

The 3D profile measurement technique is one of the key technologies in the applications of reverse engineering on mold/die design and production. An efficient and accurate technique to scan and digitize a surface profile is the first step in the faithful reproduction of a surface geometry from an existing part or clay model. in this thesis, a non-contact 3D profile measurement technique was presented which is based on the projection of parallel beams with CCD image processing techniques and triangulation algorithm. An arc light which wasassumed to be a point light source was positioned in the focal point of an parabolic mirror. After it was reflected by the parabolic mirror, uniform parallel beams were projected through the pin-hole. These parallel beams, passion through LCD, produce 128 coded patterns. The purpose ofthese coded patterns is to ensure their relative positions. CCD images were then taken on these coded patterns in order to perform space coding on each ofthe measurement point.It was followed by the calibration process with a special designed model to obtain the internal and external parameters of the CCD such as focal length and ratioof pixel size. Using the triangulation theory, coordinate transformation between the measured object and the CCD will transform the 2D image plan into 3D coordinate profile. By choosing different diameter of the parabolic mirror, theprojected area can be adjusted and thus improve the efficiency of the measurement. By increasing the number of projected patterns such as from 128 to 256 will improve the accuracy of the measurement. The parallelism of these projection beams eliminates the disadvantages ofdiffused projection light patterns, simplifies the mathematical algorithms,and reduces image processing error of theprojected patterns. This can be a more efficient and accurate technique for 3D profile measurement as compared with other non-contact measurement techniques. Key words：3D profile measurement, reverse engineering, CCD image processing, space coding.

並列關鍵字

3D profile measurement ； reverse engineering ； image processing ； space coding

國際替代計量

平行光柱投射式非接觸三次元量測技術研究

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