A posteriori insertion of information for focusing and time–depth conversion of ground‐penetrating radar data

Abstract

This paper deals with ground‐penetrating radar prospecting and exploits a semi‐heuristic strategy to account for inhomogeneous background media, empty cavities or topography of the surface. We assume here that no more than a commercial processing software is available. Customarily, commercial codes assume a homogeneous soil and a flat interface in order to achieve the focusing of the data. Therefore, this is also the model exploited here, whereas the data are referred to an inhomogeneous soil or to a non‐flat interface. The proposed strategy exploits the principle that ‘the data speak’, even if with some ambiguity and some reticence, and they can reveal or at least suggest important features of the underground scenario. On this basis, heuristically, we exploit features derived from the data themselves as a posteriori information, improving the available focusing and time–depth conversion even having at disposal a basic model of the background scenario.

GPR Mapping of Cavities in Complex Scenarios with a Combined Time–Depth Conversion

“…However, this is possible only if both the ceiling and bottom of the cavity are visible in the data. This has been shown in [22] with a simulated Bscan. Herein, the experimental data and depth slices in particular will be shown.…”

“…This paper has proposed a combined time-depth conversion (CTDC) for cavities embedded in the soil, accounting for the propagation velocity of the electromagnetic waves both in the soil and the cavity. This paper is part of a larger work [22,30] also In sum, in comparison with the homologous 5 and 7 without CTDC, Figures 9 and 11 show that the extension of the cavity along the depth is better reproduced if a CTDC is applied. Moreover, the displacement along the depth of the three pipes is also better reproduced because the dynamic of each image results automatically better calibrated by the CTDC.…”

“…This paper has proposed a combined time-depth conversion (CTDC) for cavities embedded in the soil, accounting for the propagation velocity of the electromagnetic waves both in the soil and the cavity. This paper is part of a larger work [22,30] also investigating layered media (indeed, a cavity locally represents a particular three-layered medium, with upper and lower medium equal to the embedding soil and the central one constituted by free space).…”

An innovative heuristic strategy for the management of buried scenarios with strong discontinuities

“…Consequently, if there are further targets beyond the cavities, the GPR data processing performed by means of the commonly adopted commercial software provides an image of the scenario affected by an incorrect representation of the relative depth levels. This drawback can be overcome by means of a combined time-depth conversion [4][5], as described in the following, accounting for the propagation velocity of the waves both in the (empty) cavity and in the surrounding soil. In order to apply a combined time-depth correction, both top and bottom of the cavity must be recognized in the radargram and it is needed to understand from it that the anomaly at hand is a cavity.…”