抄録
Recently, for the maintenance of the public infrastructure, a new method to check a large-scale structure is demanded. The image processing decreases the staff and can reduce costs. A purpose of this study is to detect an outside damage and to measure crack width on the structure by image photography. We used image processing and measured the extraction of the crack and the width of the crack. Our method uses edge processing, the dynamic threshold method and luminance correction formula. A robot photographed the concrete surface of the bridge from ground and was able to extract a crack of the width of around 0.2mm. This report describes that accuracy of the extraction of the crack and the width of the crack and the measurement precision of the position.
