Radiometrics Filtered K percent Image - 2015

Low-pass filtered K element concentration (percent K). The Radiometric Map of Australia dataset comprises gridsof potassium (K), uranium (U) and thorium (Th) element concentrations, and derivatives of these grids. This third edition was derived by seamlessly merging 45 new survey grids with the Second Edition Radiometric Map of Australia (Minty et al., 2010). Details of the specifications of individual airborne surveys can be found in the 2014 Edition of the Index of Airborne Geophysical Surveys (Percival, 2014). Matching of the grids in the database was achieved using a program called Gridmerge, originally developed within Geoscience Australia and has now been commercialised. This program was used to merge 45 new surveys to the Second Edition Radiometric Map of Australia. The second edition merged over 550 individual grids to create the compilation (Minty et al., 2009), and the Australia-wide Airborne Geophysical Survey (AWAGS) airborne radiometric data was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). As the second edition was used as a base grid for the Gridmerge operation the new Third Edition is essentially levelled to AWAGS. Filtering: Potassium, uranium, thorium and dose rate grids are available in both filtered and unfiltered versions. The low-pass filtering was achieved by applying a 7-point, degree-3 Savitzky-Golay filter (Savitzky and Golay, 1964) to each of the original survey grids prior to grid merging.

低通滤波后的钾（K）元素浓度（以钾百分比计）。澳大利亚放射性制图数据集包含钾（K）、铀（U）以及钍（Th）元素浓度栅格，以及这些栅格的衍生数据集。本第三版通过将45份新的实测栅格与《澳大利亚放射性制图第二版》（Minty等，2010）无缝融合而成。各航空测量项目的规格细节可查阅《航空地球物理测量索引2014版》（Percival，2014）。数据库中栅格的配准工作通过一款名为Gridmerge的程序完成，该程序最初由澳大利亚地质调查局（Geoscience Australia）研发，目前已实现商业化。该程序被用于将45份新实测数据与澳大利亚放射性制图第二版进行融合。第二版通过融合超过550份独立栅格完成数据集汇编（Minty等，2009），且采用全澳航空地球物理调查（AWAGS）航空放射性数据，对与AWAGS数据重叠的实测栅格的基准水平进行校准（Milligan等，2009）。由于第二版被用作Gridmerge操作的基准栅格，新版第三版实质上已基于AWAGS完成了水平校准。滤波处理：钾、铀、钍及剂量率栅格均提供滤波版与非滤波版两种格式。低通滤波通过在栅格融合前，对每份原始实测栅格应用7点3次萨维茨基-戈莱（Savitzky-Golay）滤波实现（Savitzky与Golay，1964）。