Hyperbolic Feature Detection and Radius Calculation of Underground Pipeline

A method of automatic recognition and extraction of echo image of underground pipeline is provided. In this method, the edges of hyperbolic features are extracted by adaptive thresholding method, and the least squares fitting method is applied to the lower edge feature points to obtain the hyperbolic curve fitting formula. Finally, by calculating hyperbolic wave velocity and fitting hyperbolic formulas, we get the information of the location and radius of underground pipeline. Based on gprMax software with finite difference time domain method, the underground pipelines with different radii are simulated to obtain the results of forward image. The proposed method is used to obtain the location and radius information of underground pipeline. The results show that the proposed method has high precision for the horizontal position and depth measurement of underground pipelines with different radii. And the method has high accuracy and robustness.