運用於傅立葉輪廓術最佳中通濾波器之研發

本研究中提出了一種最佳中通濾波器設計，將傅立葉頻譜中有效頻譜資訊萃取的更完整，有助於提高三維表面重建精度。系統使用數位投影機產生正弦條紋結構光，將正弦條紋結構光投影至物體表面，由於物體的形貌變化造成變形的正弦條紋結構光，利用三通道彩色CCD擷取變形條紋之影像，並經由傅立葉轉換將影像從空間域轉換至頻率域，傅立葉頻譜中包含著背景資訊、正弦條紋結構光資訊及各種頻率之資訊，其中條紋資訊代表物體表面相位資訊，本研究中探討各種形狀的中通濾波器，並設計最佳中通濾波器萃取傅立葉頻譜中的條紋資訊。研究中同時針對多彩物體表面做處理，當數位投影機產生正弦條紋結構光投影至多彩物體表面，正弦條紋除了會因物體形貌產生變形條紋外，也會因物體表面的色彩產生影響，使得正弦條紋明暗變化不一致，造成相位資訊錯誤。利用影像處理的方式處理物體表面色彩資訊，在影像擷取上，除了擷取一張變形條紋的影像外，另外擷取一張投影均勻背景光至物體表面之影像，兩張影像影像處理後，把物體表面色彩資訊去除，並增強正弦條紋資訊，再由傅立葉轉換得到影像處理後之傅立葉頻譜，由於背景資訊及物體色彩資訊去除，使得頻譜中背景頻譜資訊可有效降低，可有利於第一頻譜資訊的萃取。

關鍵字

中通濾波器；傅立葉頻譜；傅立葉輪轉換廓術；頻譜資訊

並列摘要

This article presents a modified band-pass filter which is used to improve the accuracy of three-dimensional surface reconstruction. Fourier Transform Profilometry (FTP) uses an image to obtain the profile information of a 3D surface. The aim of this approach is to achieve high-speed measurement. However, When projection a structure light onto a complex shape object, the slope will over the measurement limit. There is a phenomenon for the fundamental frequency and first-order overlapping in the spectrum, lead to very difficult for extracting beneficial information. Therefore, the accuracy of measurement results is influenced by collecting the correct surface information in the frequency domain using band-pass filter. So far, the ellipse filter results better than the circle filter. However, after extraction by using the ellipse band-pass filter, the reconstruction of three-dimensional shape error causes by much redundant information was extracted. Accordingly, we present the optimal band-pass filter for extracting useful information in the spectrum.

並列關鍵字

Fourier Transform Profilometry ； Band-pass filter ； Overlapping ； Spectrum

參考文獻

[27]何宣緯，具高精度與段高量測範圍傅立葉轉換三維形貌量測系統之研發，碩士論文，國立臺北科技大學自動化科技研究所，臺北，2008。

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運用於傅立葉輪廓術最佳中通濾波器之研發

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