There are times when you may need to change the coordinate system of the grid file itself, instead of just a map, for use in Surfer. This may be the case when performing grid operations such as Grid Volume or Grid Calculus or when working with 3D surface maps.
Grid Volume and Calculus commands require linear X, Y, and Z units in order to provide meaningful results. For example, a grid file with Z values in feet and XY coordinates in Lat/Lon will result in a very small volume with the units lat degrees * long degrees * feet. Similarly, slope analysis of Lat/Lon can result in all slopes being near 90°.
3D surface maps do not support coordinate systems and therefore require the same coordinate system for all grids and files used to create each map layer.
To convert a grid to a new coordinate system in Surfer, follow the steps below.
- Click Grids | Edit | Project.
- In the Grid Project dialog, click Browse, select your grid file, and click Open.
- Click Set in the Input Grid section.
- In the Assign Coordinate System dialog, select the coordinate system of the original data and click OK.
- Click Set in the Output Grid section.
- In the Assign Coordinate System dialog, select the coordinate system you want the grid converted to and click OK.
- Click OK in the Grid Project dialog to create the new grid file.
Updated September 4, 2020