20 October 2006 Optical crack following on tunnel surfaces
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Proceedings Volume 6382, Two- and Three-Dimensional Methods for Inspection and Metrology IV; 638207 (2006) https://doi.org/10.1117/12.685987
Event: Optics East 2006, 2006, Boston, Massachusetts, United States
One of the most important monitoring tasks of tunnel inspection is the observation of cracks. This paper describes an approach for crack following using mid-resolution (2-5mm per pixel) images of the tunnel surface. A mosaic on the basis of the tunnel design surface is built from images taken with a mobile platform. On this image representing the unwrapped tunnel surface texture the starting points of each crack are found semiautomatically using a modified Hough transform. Crack following takes place on the basis of local line fitting and exhaustive search in both directions of the crack, taking into account several restrictions, rules and optimization criteria to find the correct crack trajectory. A practical implementation polygonizes the extracted cracks and feeds them into a tunnel inspection data base. The method is applicable to various types of background texture as expected in the tunnel environment.
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Gerhard Paar, Maria d. P. Caballo-Perucha, Heiner Kontrus, Oliver Sidla, "Optical crack following on tunnel surfaces", Proc. SPIE 6382, Two- and Three-Dimensional Methods for Inspection and Metrology IV, 638207 (20 October 2006); doi: 10.1117/12.685987; https://doi.org/10.1117/12.685987

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