Image Mosaicking of a Section of a Tunnel Lining and the Detection of Cracks through the Frequency Histogram of Connected Elements Concept

摘要

This study aims to further the image mosaic technology, which helps to assemble the images obtained from a digital camera and eventually obtain a layout image of the lining surface. With the extensive use of mathematical correlations for distortions produced due to perspective, the errors and use of other machines has significantly reduced. The layout of the lining surface obtained from successive mosaic of partially overlapping images, which are represented as 2D orthographic-like and are rectified to form the 3D tunnel-lining surface. A test was carried out in the experimental tunnel to validate the proposed method and to examine its practicability. The anomalies on the tunnel-lining surface are usually cracks or a water leakage at any point, neither of which were identifiable through edge detection. Through the application of a slightly modified Frequency Histogram of Connected Elements method, the resultant image successfully identified the anomalies on the tunnel lining.