Airborne GeophysWeb: Information on Images and Survey Borders
Please contact DGGS at firstname.lastname@example.org with any feedback or questions.
NOTE: Images will be added at a later date. More information will be provided on the key points below at that time.
- Images are colored to reflect information about that polygon, and are typically colored independently from others.
- Ranges are vastly different between borders (polygons), showing fine differences in images with a small range, and only the larger anomalies when a larger range is used.
- Mixed types of data appear on each layer:
- Magnetics are a mixture of total field magnetics (TFM) (around 55,000 nT) and residual magnetic intensity (RMI) (commonly, but not always centered around 0 nT). Nanoteslas (nT) is the magnetic unit.
- Apparent resistivity have different frequencies displayed, most commonly 7200 Hz of 900 Hz.
- Radiometric data are typically one of three ratios of elements, such as "ppm Thorium / percent Potassium". The type of ratio will vary by polygon, depending on what appears most visually interesting.
- Color bars are different on different layers. Magenta means high values on magnetics and radiometrics, and dark blue or black mean high values (very resistive) on apparent resistivity images.
Survey Borders (polygons)
- When surveys are flown adjacent to another, an overlap is necessary.
- DGGS borders: The boundaries for the DGGS polygons do not show the overlapping border. Currently the borders are shown with the older boundary as it was, and the overlap caused by the new survey is not. This may be changed in the future. The newer surveys, particularly when applied to surveys a number of years apart, have a better ability to distinguish among resistive rocks than older surveys.
- USGS borders: The boundaries for USGS polygons show the overlapping border.
Please refer to the User's Guide for additional information on how to use the Airborne GeophysWeb interface.