使用照相機作三維大範圍表面形貌量測之研究

Study on the Measurements of Three-dimensional Large Surface Profiles by Using a Camera

陳姵妃(Pei-Fei Chen)

指導教授 ： 邱銘宏

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2012年)

https://doi.org/10.6827/NFU.2012.00195

摘要

本論文提出「使用照相機作三維大範圍表面形貌量測之研究」。使用試誤法與臨界角法兩種方法進行實驗，試誤法基本原理是以平行四邊形稜鏡搭配單眼照相機，藉由光強度比例函數對表面高度的轉換成為第三維，結合原有之二維影像，而量測出待測物之三維表面形貌。在白光下，光打至待測物反射經過一偏極片，並使光偏極為s偏極光，然後此光束進入平行四邊形稜鏡，利用臨界角特性，轉動稜鏡從全反射角到近臨界角之特定角度，由單眼照相機拍攝二張照片傳入至電腦，在一個設定的位置上，一張有待測物，一張無待測物，經由位置與光強度之關係，再由Matlab程式所撰寫之程式碼做三維圖形轉換，即可得到待測物的三維表面形貌。臨界角法基本原理是以平行四邊形稜鏡搭配單眼照相機，藉由反射率對表面高度的轉換成為第三維，結合原有之二維影像，而量測出待測物之三維表面形貌。在自然光下，光打至待測物反射經過一偏極片，並使光偏極為s偏極光，然後此光束進入平行四邊形稜鏡，利用臨界角法，轉動稜鏡在全反射角與在近臨界角之特定角度，由單眼照相機分別拍攝二張照片傳入至電腦，算出每點上的反射率值，再經由Matlab程式所撰寫之程式碼做三維圖形轉換，即可得到待測物的三維表面形貌。此架構十分簡單且為非接觸式非破壞性檢測，可應用於外觀形貌作大面積之檢測，也可應用於形變量測，例如：臉型辨識，或用於整容前後臉型比對。

關鍵字

照相機 ； 表面形貌 ； 臨界角

並列摘要

This paper entitled as “Study on the measurements of three-dimensional large surface profiles by using a camera.” is presented. One way is used try-and-error method and the other is the critical angle method. The first method is based on the proportion function-to-height transformation using a parallelogram prism near at the critical angle condition. The second method is based on the reflectance-to-height transformation, the incident angle of a parallelogram prism is set at from total internal reflection to the angle less than the critical angle. The height difference of two adjacent points on the test surface is proportional to the angle deviation of the reflective ray. The angle deviation is also proportional to the reflectance of the prism. Thus, measuring the reflectance can be used to transform the surface height directly. Adding the two-dimensional image from a digital camera, the three-dimensional profile is obtained. We measured the reflectance in the s-polarization for the purpose of obtaining larger dynamic range. There are two images captured at two angles, one is recorded near to the critical angle and the other is recorded at the angle of TIR. Overlapping these two images well, the reflectance difference pattern will be obtained.
According two metioned above, the three-dimensional profile is achieved. The structure of the 3-D camera is very compact and is very easy to operate. It can be used to measure the surface distortion, for example, a facelift measurement, may be applying this method in the future.

並列關鍵字

three-dimensional ； surface profiles ； critical angle

參考文獻

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