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How to reproject a Geosoft grid in ArcMap

Joe McPherson

Objective:

I would like to reproject a Geosoft grid in ArcMap.

Resolution:

To reproject a Geosoft grid in ArcGIS :
  1. From the ArcToolbox, expand Data Management Tools > Projections and Transformations > Raster and double-click Project Raster.
  2. Browse to and select the Input Raster (i.e. the Geosoft grid).
    You can also drag and drop a layer from the Table of Contents (ToC) to this field.
    The file's coordinate system will display if it is already defined.
  3. Specify the Output Coordinate System.
  4. Specify the Geographic Transformation if you are reprojecting across datums.
  5. If you have continuously sampled data, such as elevation or airborne geophysical data, set the Resampling Technique to Bilinear or Cubic.
  6. You can optionally change the Output Cell Size.
  7. Click Ok.
    The reprojected raster layer will appear in your ToC and is saved to your default File Geodatabase.

To save the reprojected raster layer to an ESRI BIL file:

  1. Right-click the output layer in the ToC, select Data and click Export Data.
  2. Do not change the default options for Extent and Spatial Reference.
  3. From the Format drop-list, select ESRI BIL.
  4. Select a Location and enter a Name for the output file.
  5. Click Save.
  6. Click No on the next prompt.

The ESRI BIL can be converted to a Geosoft grid if required but the Geosoft dialog boxes in ArcMap can read the BIL format directly.

To convert the BIL to a Geosoft grid:

  1. From the Geosoft Database toolbar, select Geosoft Data > Gridding > Copy/convert grids.
  2. Click Browse to the right of Input Grid File.
  3. For Files of type, select BIL with *.hdr header (*.*).
  4. Then select the {file name}.bil file you saved as the reprojected raster layer > click Open.
  5. Enter a name for the Output Grid File.
  6. Click OK.

Although the converted Geosoft grid is in the reprojected coordinate system (i.e. the coordinate values for the grid cells have been reprojected), its coordinate system must be set as it did not carry over from the Copy/convert function.

Notes:

In order to read Geosoft grids with ArcGIS, you must have either the Geosoft Extensions for ArcGIS or the Geosoft Plug-in for ArcGIS installed.