In Surfer, data, grids, map layers, and maps can have an associated coordinate system. All coordinate systems defined by the data, grids, and map layers are converted "on the fly" to the map's target coordinate system. This allows maps with different coordinate systems to be easily combined in Surfer.
The standard procedure for creating maps in a specific coordinate system is as follows:
- Create the map by clicking on the appropriate Home | New Map command.
- In the Open Grid(s) dialog, select the file to open and click Open.
- In the Contents window, click on the map layer to select it.
- In the Properties window, click on the Coordinate System page.
- If the Coordinate system is not correct, click the Set button next to Coordinate System. The Assign Coordinate System dialog opens. This is the initial coordinate system for the map layer, i.e. the coordinate system for the source data. Select the correct coordinate system in the dialog. When finished making changes, click OK.
- To change the target coordinate system for the map, click on the Map object in the Contents window. In the Properties window, click on the Coordinate System tab. This is the coordinate system in which you want the map to display.
- Click on the Change button next to Coordinate System to set the desired target coordinate system. When finished, click OK.
- All of the map layers are converted on the fly to the target coordinate system. The entire map is now displayed in the desired coordinate system.
Surfer does not require a map coordinate system be defined. Maps can be created from unreferenced data, grid, and map layers. As long as all map layers have the same X and Y ranges, coordinate systems do not need to be specified. If you do not specify a source coordinate system for each map layer, it is highly recommended that you do not change the target coordinate system. Changes to the target coordinate system for the map can cause the unreferenced map layers to appear incorrectly or to not appear.