Interpolation methods in GPR tomographic imaging of linear and volume anomalies for cultural heritage diagnostics

This paper presents results of a ground penetrating radar (GPR) survey conducted in St. Joseph's Church in Gdansk, Poland. The aim of the study was to produce tomographic imaging of a renovated floor as well as the objects buried under the floor to detect linear and volume inclusions. The assumed track spacing was meaningfully greater than the single signal spacing in each track, which induced the need for interpolation methods to estimate signal values in the areas beyond the trace lines. Various interpolation techniques were used to prepare the tomography maps. GPR time slices allowed the identification of reinforcing meshes, underfloor heating system elements and the foundations of entrances to crypts. The results obtained were compared to the exact images acquired in a dense regular grid to evaluate the efficiency of the applied interpolation methods and to verify the possibility of conducting GPR surveys with coarse track spacing. (C) 2020 The Author(s). Published by Elsevier Ltd.