An image reconstruction method using GPR data

The spatial resolution of a ground penetrating radar (GPR) system using traditional interpretation methods is largely dependent on the isolations of echoes. It is difficult to identify weak echoes that are mixed with either direct waves or other larger echoes; especially, when the media is absorptive, the reflections cannot be identified from the tail of the direct wave. The authors present an iterative algorithm to reconstruct the image of the subsurface using time-domain waveforms. The forward modeling employed in the algorithm is derived from the transmission line matrix (TLM) method with a perfect matched layer (PML) absorbing boundary. One-dimensional (1D) inversion algorithm is briefly described, based on which, a two-dimensional (2D) inversion method is developed. The inversion algorithm proceeds iteratively in space and time step by step. The inversion algorithm is tested in cases in which both lD and 2D variations exist. The developed inversion method is used to reconstruct the images of buried objects using GPR data with echoes buried in the direct waves. The results show a superior resolution and stability.