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Chapter 7 - Base Maps
Placing Boundaries on Other Maps
Base maps can be used to place boundary features on any type of map. When you want to place
boundary lines on a map, create the base map, select all maps, and then use the Map | Overlay
Maps command to combine the maps. The maps must use the same coordinate system or they
will not overlay correctly.
Coordinates
Base map file coordinate systems must use the same units and be reasonably close to each other to
avoid the extreme scaling of one map or the other. Surfer merges the coordinate systems of the
individual maps. For example, consider a contour map based on latitude/longitude coordinates.
To overlay a base map on the contour map, the base map must also use latitude/longitude
coordinates in the same general range as the contour map.
Limits and Scale
When overlaying maps, the composite map limits are based on the greatest extent determined from
all the overlays included in the composite map. For example, you may have a base map that
covers a much greater extent than the contour map on which you want to display boundary
information. When you overlay these maps, the limits are based on the overlay with greater
extent, and the other overlays might be quite small within the limits of the composite map. When
this occurs, you can clip the limits of the map to the smaller overlay limits using the map
properties Limits page. The scale can then be changed using the map properties Scale page.
To place a boundary on a map:
1.
Create a map, such as a contour or wireframe. The grid file should use limits that cover the
same general XY extent as the base map.
2.
Choose the Map | Base Map command, or click the
3.
Select the file containing the boundaries you want to include on the map. Click Open and an
import options dialog appears.
button.
4.
Select import options for the map and click OK. The base map is drawn.
5.
Select the maps. If there are the only maps in the plot window, click Edit | Select All to
select both maps.
6.
Choose the Map | Overlay Maps command to create a single composite map.
7.
To clip the map to specific limits, open the map properties and select the Limits page. If
necessary, set the map scale on the Scale page.
8.
Click OK or Apply to redraw the map.
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