Applying Interpolation Methods for Ground Penetrating Radar (GPR) Topographic Correction at a Lithuanian Holocaust Mass Burial Site

Abstract

A ground penetrating radar (GPR) grid was collected to locate a Holocaust mass burial site in the Trakas-Pempiškis woods of Rokiškis, Lithuania. The survey, shot with a pulseEKKO Pro GPR system and 500 MHz antennae, consisted of 28 parallel GPR lines approximately 9 m in length and spaced 0.25 m apart. A Topcon RL-H4C laser leveler was used to measure topographic points surveyed every 1 sq. m. Historical eyewitness testimony and a truncation in subsurface stratigraphy beneath a surface depression suggested the presence of the burial site. Aiding interpretation of GPR data, we identified 13 unique Ordinary Kriging (OK) and Radial Basis Function (RBF) digital elevation models (DEMs) for GPR line topographic correction. Presumably, OK and RBFs produce DEMs passing through input points and predict values beyond minimum and maximum input point values, both desired attributes for logical consistency. In practice, OK and some RBF DEMs insignificantly exceeded minimum and maximum sample data values while other RBF DEMs exceeded both. Due to relatively large topographic sample point spacing, profiles are only adjusted for general trends in elevation change, and an analyst must be cognizant of individual lines’ placement affecting uncertainty of correction.