結合數位影像相關法與光場相機新型量測系統之研發

RESEARCH AND DEVELOPMENT OF THE NOVEL MEASUREMENT SYSTEM BY INTEGRATING DIGITAL IMAGE CORRELATION METHOD AND LIGHT FIELD CAMERA

牙璽喬(Ya,Hsi Chiao)

指導教授 ： 王偉中

國立清華大學/工學院/動力機械工程學系/碩士(2015年)

摘要

本研究特別製作螢光粉矽膠透明試片 (以下簡稱螢光粉試片)，以嘗試突破目前DIC法系統僅限於量測不透明物體表面形貌的限制。本研究結合數位影像相關(Digital Image Correlation, DIC)法系統與現今流行的光場相機(Light Field Camera)建立一創新的光學量測系統首次挑戰模擬體積數位影像相關(Volume Digital Image Correlation, VDIC)法的機制，以量測試片內部的變形。而為了驗證本研究所建立之創新量測系統的可行性，亦進行了使用傳統斑點試片做相同的實驗以做比對。
本研究總共進行四個實驗，其中三個實驗係使用螢光粉試片探討DIC法的使用極限，依序為2D-DIC法剛體平移實驗(使用鋁板試片與螢光粉試片)、2D-DIC法四點彎矩實驗(使用白色斑點試片與螢光粉試片)、3D-DIC法面外位移實驗(使用白色斑點試片與螢光粉試片)。第四個實驗為應用創新的光學量測系統於階梯試片位移的量測，主要是利用光場相機重新對焦的特色，藉以展現光場相機在量測上的優勢，並利用傳統DIC法系統去探討與驗證創新光學量測系統的可行性。
研究結果上，螢光粉試片在2D-DIC法的量測因為理論值與實驗值誤差很小，因此可驗證量測結果佳，但在3D-DIC法上的量測因為斑點遮蔽效應嚴重而無法分析。階梯試片位移實驗中，在聚焦面的量測因為影像的解析度更佳，斑點匹配時的誤差降低，所得到的DIC結果更為準確。雖然本研究限於現有光場相機的規格及操作技術的純熟度，所獲得之研究成果尚不盡理想，但是根據國外最新光場相機的技術報導，結合光場相機與DIC法的光學量測系統應具有相當的應用潛力。

關鍵字

數位影像相關法 ； 光場相機 ； 光場成像理論 ； 矽膠

並列摘要

This research integrated the digital image correlation (DIC) method system with the currently popular light field camera to establish a novel optical measurement (NOM) system. To attempt to break through the current DIC technique with limitation on measuring surface topography of opaque bodies, this research manufactured transparent specimens made of PDMS mixed with phosphor powder (hereinafter called phosphor powder specimen). To investigate the feasibility of measuring the internal deformation by using the established NOM system, this research attempted to simulate the volumetric digital Image correlation (VDIC) method. To compare the experimental results obtained by the NOM system with the traditional DIC method system, same experiment was performed on the transparent specimens with spray coating.

Four types of experiments were performed in this research. To the phosphor powder specimens, three experiments were implemented to study the limit of the DIC method, including rigid body translation experiment by the 2D-DIC method (for the aluminum plate and phosphor powder specimens), four-point-bending experiment by the 2D-DIC method (for the white PDMS specimen covered with random black speckle pattern and phosphor powder specimen) and out-of-plane displacement experiment by the 3D-DIC method (for the white PDMS specimen covered with random black speckle pattern and phosphor powder specimen).

The fourth experiment was performed by using the NOM system to the displacement measurement of a step-shaped specimen. The characteristic of this experiment is to demonstrate the refocus feature and the measurement superiority of the light field camera. Traditional DIC method was also used to compare and verify the NOM system.

Regarding the phosphor powder specimens, in contrast to the small difference between the theoretical and experimental results obtained by the 2D-DIC method, displacement measurement was unable to carry out by the 3D-DIC method due to the shielding effect of speckles.

On the displacement measurement experiment of the step-shaped specimen by the 2D-DIC method, better image resolution on the focal plane was achieved and lower matching error in the speckle matching process was obtained. Therefore, accurate results were obtained. Because of the specification limit and insufficient operational experience of the light field camera, the results obtained by using the NOM system in this research are not satisfactory. However, based on the latest report of the technology development of the light field camera, the NOM system has full potential to become a useful system.

並列關鍵字

Digital image correlation (DIC) method ； Light field Ccmera ； Light field rendering ； PDMS

參考文獻

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