WATER LEAKAGE DIAGNOSIS IN METRO TUNNELS BY INTERGRATION OF LASER POINT CLOUD AND INFRARED THERMAL IMAGING

Diagnosis of water leakage in metro tunnels is of great significance to the metro tunnel construction and the safety of metro operation. A method that integrates laser scanning and infrared thermal imaging is proposed for the diagnosis of water leakage. The diagnosis of water leakage in this paper is mainly divided into two parts: extraction of water leakage geometry information and extraction of water leakage attribute information. Firstly, the suspected water leakage is obtained by threshold segmentation based on the point cloud of tunnel. And the real water leakage is obtained by the auxiliary interpretation of infrared thermal images. Then, the characteristic of isotherm outline is expressed by solving Centroid Distance Function to determine the type of water leakage. Similarly, the location of leakage silt and the direction of crack are calculated by finding coordinates of feature points on Centroid Distance Function. Finally, a metro tunnel part in Shanghai was selected as the case area to make experiment and the result shown that the proposed method in this paper can be used to diagnosis water leakage disease completely and accurately.

An Exploration with Novel Shape Signature of GMSC Distance Function to Track the Object

The process explicitly dedicated to estimate the path of the object as it moves along the region of scene in the image plane is the principle of tracking. In other words, it is a strategy to detect and track moving object through a sequence of frames. In this work, optical flow based on Horn–Schunk with Barren, Fleet and Beuchemin (BFB) kernel has been employed to estimate the motion vectors. The peripheries of moving objects are extracted for different shape signatures such as boundary, edge, area, curvature and centroid distance functions. Fourier descriptors (FD) of particular shape signature for each of the candidate templates and model template are computed. Similarity between the model template and candidate templates is confirmed by corresponding minimum Minkowski distance (MD). Subsequently, best match candidate template will be updated by model template in view of tracking process. However, centroid distance function has remarked some potentials and hence it has further motivated to mine it to throw in the proposed novel criteria such as the geometric mean of segmented centroid (GMSC) distance function to track the object. The proposed method of GMSC distance function has shown significant change in the tracking outcome.