Radiation Geophysics
Products
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:
Open File No. |
GSC Information Circular |
Description |
1035 |
June 1984 (List 925) |
Airborne Radioactivity Survey Film (video-cassette) |
2661 |
May 1993 (List 1025) |
SurView: a Microsoft Windows Application to View Geophysical Survey Data |
3061 |
April 1995 (List 1045) |
Workshop Manual: Applications of Gamma-Ray Spectrometry & Magnetic/VLF-EM Surveys |
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:
Rob B. K. Shives
Head, Radiation Geophysics Section
Geological Survey of Canada
601 Booth St., Room 571
Ottawa, Ontario, K1A 0E8
Voice: (613) 996-3695
FAX: (613) 996-3726
e-mail:
NatGam@gsc.nrcan.gc.ca
Digital data purchased from the Radiation Geophysics Section is accompanied
by the following Licence Agreement:
The digital data and/or SurView application supplied are under Crown
copyright. They are supplied on the understanding that they are for
the SOLE USE of the purchaser and are NOT to be DISTRIBUTED in any
form to third parties. In acknowledging receipt of the data, the
purchaser undertakes to abide by the foregoing legal requirements
implicit in the purchase.
http://www.gsc.nrcan.gc.ca/gamma/prod_e.php