Since Surfer 10, users have been able to create maps using layers that contain data from different coordinate systems and reproject the layers to the desired coordinate system on the fly. This valuable feature has streamlined workflows, eliminating the need to transform all data to the same coordinate system before using it to create multi-layered maps. For an example, see the sample file CoordinateSystems.srf, located by default at C:\\Program Files\\Golden Software\\Surfer 12\\Samples. Let's take a look at this powerful component of Surfer's 3D Mapping software!
Know your data
If your data file has coordinate system information embedded, or if Surfer finds an associated location reference file (for example, a PRJ file), Surfer will automatically assign the coordinate system for the map layer when it is created. If no location information is found, or if location information is recognized, but is incorrect, the coordinate system can be manually assigned. It is important to know the coordinate system of the data and where in the world the data is located. An improperly assigned coordinate system can result in undesired results.
Source coordinate system vs. target coordinate system
There are two coordinate systems to consider when working with maps and map layers in Surfer's mapping software: the source coordinate system and the target coordinate system. The source coordinate system is the coordinate system of the data, and the target coordinate system is the coordinate system in which the map is displayed. The two coordinate systems may be the same, or may be different, for a map.
Source coordinate system
The coordinate system of the data used to create a map layer is the source coordinate system. When a map layer is selected, the source coordinate system is displayed on the Coordinate System page of the Property Manager. If Surfer is unable to find location information for the data, Unreferenced local system is displayed for the Name. In this case, or if the location information is incorrect, you can set the source coordinate system for the layer. If the source coordinate system is incorrectly specified, you may see a blob, a mess of black lines, or your map may disappear or locate incorrectly when overlaying it with other data.
The image below shows what the Coordinate System page of the Property Manager looks like for a map layer before and after specifying a source coordinate system. Note that the page says Source Coordinate System, and the button reads Set.
Coordinate System page for a map layer before and after assigning a source coordinate system.
To specify a source coordinate system for a layer:
The Property Manager updates with the newly assigned coordinate system.
Target coordinate system
The coordinate system in which the map is displayed is the target coordinate system. This may be different from (or it may be the same as) the source coordinate system. When the map itself is selected, the target coordinate system is displayed in the Property Manager. If no target coordinate system is defined, Unreferenced local system is displayed for the Name. Change the target coordinate system to change the coordinate system in which the map is displayed, and change the values of the coordinates displayed on the axes.
The image below shows what the Coordinate System page of the Property Manager looks like for a map before and after specifying a target coordinate system. Note that the page says Target Coordinate System, and the button reads Change. Additionally, the image above and the image below were taken from the same map. Note that the source coordinate system is different from the target coordinate system.
Coordinate System page for a map before and after assigning a target coordinate system.
To specify a target coordinate system for a map:
The Property Manager updates with the newly assigned coordinate system, and the values displayed on the axes update to reflect the new coordinate system.
When and why assign a coordinate system?
There are a few cases in which a coordinate system is necessary for a map or a map layer:
To see this feature in action, take a look at our training video Setting and Changing Coordinate Systems for Maps. Additionally, the information contained in this article (and more) can be found in various Surfer Knowledge Base articles.
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