How can I convert the coordinate system of a BLN file in Surfer?

If you convert the coordinate system of a BLN file in the worksheet, then the headers for all the objects in the BLN file are also converted. This is generally undesirable.

Since there is not a way for Surfer to ignore the BLN header rows in the worksheet, converting the coordinate system of a BLN file is probably easiest to do in the plot window instead of the worksheet. 

For example:

  1. Click Base | New Map | Base | Base, select the BLN file and click Open.
  2. Select the Base layer in the Contents window, and in the Properties window, on the Coordinate System tab, make sure the correct coordinate system is specified for the layer. If not, click the Set button, select the appropriate current coordinate system for the BLN file and click OK.
  3. Now select the Map in the Contents window, and in the Properties window, on the Coordinate System tab, click the Change button. Change the coordinate system to the one you want the coordinates to be in (the target coordinate system) and click OK.
  4. Turn off all four axes in the map by unchecking them in the Contents window, so that you just see the point, polyline and/or polygon objects on the screen.
  5. Click File | Export.
  6. In the Export dialog set the Save as type to BLN Golden Software Blanking (*.bln), give your file a name and click Save.
  7. In the Export Options dialog:
    1. On the Scaling tab set the Scaling source to your Map. 
    2. On the Spatial References tab check one of the external reference file types.
    3. On the BLN Options tab, in the NoData section, verify that the NoData direction is correct.
    4. Click OK to create the new BLN file.


Updated September 12, 2017

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