Image processing method for crack area extraction of tunnel lining surface image

摘要

PROBLEM TO BE SOLVED: To enable assessment of the level of soundness (or of deterioration) of the covered face of a tunnel to be accomplished on the deformed condition of the face while restraining erroneous detection of non-cracked areas as cracked areas and making possible reliable automatic extraction of cracks.SOLUTION: By using a feature quantity selected regarding at least one area other than cracked areas and a threshold or a numerical value range, at least one or more areas are identified out of images of covered areas of a tunnel (steps 103, 104, 107, 108, 111 and 112). The at least one or more areas are masked in the images of covered areas of the tunnel (steps 105, 109 and 113), and a cracked area is identified out of the images of cracked areas of the tunnel by using the feature quantity selected regarding the cracked area and the set threshold or the numerical value range (step 115) to identify the cracked area (step 116).SELECTED DRAWING: Figure 7