| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 99 === Digit image measurements are based on the digit images of an object before and after deformation. Through the spatial information analyses on the image of an object surface taken from two cameras, related data such as displacement fields, strain fields, and crack positions et al. can be obtained. In the past few years, the rapid improvement and popularization of digital camera technology have greatly facilitated the applications of the digital image measurement in experimental mechanics. However, there still lacks of an appropriate index to estimate the accuracy and precision of the digit image measurements.
The aim of this research is to construct the error level of three-dimensional digit image measurement based on the theory of error propagation. The error of strain calculation in the three-dimensional image measurement resulted from the errors of stereo-match and triangulation in image processing are firstly derived. The analytical formula is then verified by an in-house developed dual-camera system. Through the zero-strain experiment, plate tensile test, and cylindrical compressive test, experimental results demonstrate that the resolution of the developed dual-camera system can achieve 0.3 pixel in displacement measurement and 0.05% in strain measurements.
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