三維外形量測之色彩耦合及不平衡校正方法

Abstract

本論文主要研究在數位條紋投影法中，因色彩耦合與不平衡效應產生的誤差，並提出強度校正策略。首先建立一個三維強度查詢表，用來儲存電腦中設計的理想強度與實際量測強度之間的差異。之後逆向操作三維強度查詢表，目的是找出量測強度所對應的投影強度，為了這個目的，我們發展出一套搜尋方法。這兩個方法可以補償色彩耦合和不平衡效應所造成的誤差，除此之外，非線性數位條紋誤差也可以透過此方法降低誤差。本文整合一套結合相位移步驟、相位壓縮步驟、相位展開步驟、強度校正的整合程式。利用此程式，測試數個量測範例。透過不規則曲面、不同表面色彩與材質待測物的三維外形量測結果可知，本文提出之誤差校正策略能有效改善重建輪廓品質。

This thesis studies an intensity correction method to reduce errors induced by color coupling and color imbalance for measuring 3D shapes of objects. First, 3D look-up table (LUT) is established for storing the difference between the assigned projected intensities and the measured intensities. Our objective is to find he corresponding input color given the measured color, which is the reverse process of the creation of the look-up table. For this purpose, we developed a search algorithm. The two methods are developed to compensate for errors caused by color coupling and imbalance. In addition, the two methods are used to further reduce nonlinear digital fringe error. An integrated program is developed by combing phase-shifting process, phase-wrapping process, phase-unwrapping process, and intensity correction. With the developed program, several measurement examples are investigated. The results demonstrate that the purposed advanced error correction strategy offers good feasibility for improving the quality of reconstructed 3D shapes.