Abstract
The objective of the study is to measure the displacement of the crack by using a digital camera image. In this measurement technique proposed here, the reflective targets are installed at the measurement point around the crack as gauges and the digital image of reflective targets is subjected to process which consists of image processing and photogrammetry, and the two dimensional displacement of the crack is calculated based on the coordinates of reflective targets. In this paper, experiments were performed to verify the accuracy and precision of the measurement. This paper also showed the actual tunnel measurement results to demonstrate that the cracks on the tunnel wall by using this method.
