For each airborne gamma-ray spectrometry survey, both analogue products and digital data are released in a variety of point/line & grid/image formats.

Analogue products include:

• maps of 7 primary radiometric elements:
  • POT^* - Potassium (K, %)
  • URA^* - equivalent Uranium (eU, ppm)
  • THO^* - equivalent Thorium (eTh, ppm)
  • ADRN^* - Natural air absorbed dose rate (ADRN, nGy/h)
  • RUT^* - equivalent Uranium/equivalent Thorium (eU/eTh)
  • RUK^* - equivalent Uranium/Potassium (eU/K, ppm/%)
  • RTK^* - equivalent Thorium/Potassium (eTh/K, ppm/%)

• TER^* ternary radioelement map (K, U, Th)

• maps of secondary products:
  • MTF^* - magnetic total field (nT)
  • MVG^* - magnetic vertical gradient (computed, nT/m)
  • VTF^* - VLF total field (%)
  • VQU^* - VLF quadrature (%)

• booklets for a single map sheet, comprising:
  • maps of primary & secondary variables (as above)
  • simplified topographic overlay
  • simplified geology overlay
  • stacked profile sections for all measured variables

^* acronyms commonly used in filenames for these products.

Digital products include:

• grids (K, eU, eTh, Exposure, eU/K, eTh/K, eU/eTh)
  These are binary floating-point flat raster files.

• ternary (K, eU, eTh) image
  This is a binary 8-bit 3-band BIL (Band Interleaved by Line) image file that has been created from the original K, eU & eTh files using an algorithm tailored to the unique character of radiometric data (Broome et al, 1987).

• multivariable point (flight line) data - all measured variables
  This is a binary file in the Section's proprietary Survey Line Data (SLD) format. It is designed for viewing with the SurView software (provided free with the data).

The grid & ternary image files are simple flat raster files. There are no headers or language-specific record delimiters (i.e. FORTRAN) embedded in the files, allowing them to be read with simple applications written in any programming language, including FORTRAN (with some care), C, Pascal & QBASIC. The header information (shape, size, description) is provided in separate ASCII files.

For no particular reason, the SLD file format (for multivariable line data) is not publicly documented, but SurView provides facilities to export the data to popular formats (i.e. XYZ text files).

Digital line (point) and gridded data ordered from the Radiation Geophysics Section is supplied in the Section's proprietary SLD (line) & GRI (grid) binary formats. Every set of digital line (point) or gridded data ordered from the Section is accompanied by the following free software for viewing and printing the line and gridded data, as well as converting it to other file formats:

• SurView: a viewing & printing application for Microsoft Windows (3, 95, NT) that handles line (point) and gridded data (runtime copy only, with import and other tools disabled) SurView can also export .SLD multivariable data file to:
  • ASCII XYZ (Geosoft & Geopak formats)
  • ASCII Arc/Info AML format (flight lines, profilemaps, labels)
  Note: these export capabilities used to be provided by the now-obsolete CONVSLD.BAS application.

• CONVGRID.BAS, a DOS QBASIC utility for converting the supplied .GRI binary grid files to:
  • ASCII Grid eXchange Format (GXF) files
  • binary 8-bit image (i.e. for PCI)
  • ASCII Arc/Info (for the 'ASCIIGRID' import command)
  • Geosoft 16-bit binary grid files

The following Open File special products are also available:

Current NATGAM airborne gamma-ray spectrometry survey coverage.

For each airborne gamma-ray spectrometry survey, the Section releases both analogue and digital products, in a variety of point/line & grid/image formats. Each survey is assigned a GSC Open File number that is listed in the GSC Monthly Information Circular along with a short description.

The prices and ordering information for the digital and analogue products of each Open File release are listed in the GSC Information Circulars. For custom orders or to enquire about the availability of data for a specific area, please contact:

Digital data purchased from the Radiation Geophysics Section is accompanied by the following Licence Agreement: