Coordinate System Frequently Asked Questions
Q: Do I need to specify a coordinate system for every map layer in Surfer?
A: You do not need to specify a coordinate system for your map layers in Surfer if you are not going to be converting between different coordinate systems or displaying maps from different coordinate systems. If all your map layers are in the same system, you do not need to specify the coordinate system.
However if all map layers are in the same coordinate system and you wish to specify the coordinate system, the map's Target Coordinate System can be applied to the layers' Source Coordinate Systems simultaneously with the Assign now button in the Properties window.
Q: Why would I want to set the coordinate system for a map?
A: If your data, grids, and base maps are in different coordinate systems, you will want to set the coordinate system for each map layer and the entire map. If you want to change the projection of your data, grid, or base map, you will want to set the coordinate system.
Q: Is there an easy way to define the coordinate system for my map and all layers at once?
A: Yes, but only when the unreferenced map layers all use the same coordinate system. If applicable, define the Source Coordinate System for any layers that do not share the same coordinate system as the other layers. Next verify that the Source Coordinate System is set to Unreferenced local system for the layers that you wish to set to the same coordinate system. Finally, set the Target Coordinate System for the map to the coordinate system shared by the unreferenced layers, and then click the Assign now button in the Properties window.
Q: How do I set the coordinate system for a data file?
A: Set the data file coordinate system using the worksheet's Data | Coordinate System | Assign Coordinate System command. The spatial reference information is saved in an external GSR2 file.
Q: How do I set the coordinate system for a grid?
A: Set the grid file coordinate system using the Grids | Edit | Assign Coordinate System command. The spatial reference information is saved in an external GSR2 file.
Q: If my data file has a coordinate system defined, do I need to define a different coordinate system for the grid?
A: If the grid was created from the data file after the coordinate system was defined, you do not need to define a coordinate system for your grid separately. Surfer automatically carries the coordinate system definition from the data to the grid and to any maps created from the data or grid.
Q: My map disappears after defining a coordinate system! Now what can I do?
A: Most likely, the map layer that disappeared did not have a defined coordinate system. In the Contents window, click on the map layer that has disappeared. In the Properties window, click on the Coordinate System tab. Click the Set button and define the map layer's coordinate system. Click OK. The map should now appear correctly. See the Source Coordinate System page for more information.
Q: My axes do not show the correct coordinates. How can I make them show the coordinates I want?
A: If the map axes are showing incorrect coordinates, you may need to change your Target Coordinate System. Click on the Map object in the Contents window. In the Properties window, click on the Coordinate System tab. Click the Change button to define the map's target coordinate system. After making the change, click OK. The map axes will now appear in the desired coordinates.
Q: When I import a map from another program, does it import the projection information?
A: If the map contained a reference file, Surfer will automatically read the reference file and apply any information it finds to the map layer.
Q: When I change the target coordinate system, my map limits change.
Surfer retains the map size, but the limits change when the target coordinate system changes.
Q: I need additional information about coordinate systems. Do you have any references that can help?
A: A good starting place is the references on the Projection References page. Many other good resources are available either online or in printed documentation.