Plotting a Portion of the Globe

You do not always have to display the entire globe, you can view just a section of the globe by defining an area by latitude and longitude in the Map Panel. This example displays the North American Continent using the Miller Cylindrical projection.

  1. Open an iMap window by typing IMAP at the IDL command line.
  2. Select Operations →  Map Projection. This command opens the Map Projection dialog, shown below.
  3. Choose the Hammer projection from the Projection pull-down list.
  4. Change the Longitude and Latitude settings as follows (and shown to the right):
    imap_hammer.gif
    • Longitude minimum -130
    • Longitude maximum -70
    • Latitude minimum 10
    • Latitude maximum 55

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  5. Click OK. The iMap window now displays a grid:
    imap_hammer_grid.gif

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  6. Now add a map to display on this grid. From the iMap menu, select Insert →  Map →  Countries (high res). The countries within the specified area appear on the grid.
    imap_hammer_northam.gif
  7. For better readability, you can change the way the grid and annotations appear. From the iMap menu, select Window →  Visualization Browser.

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    imap_map_grid_properties.gif

  8. In the Visualization Browser, expand the tree view until you can see the Map Grid item. Double-click on Map Grid to expand the browser and display the Map Grid properties. Make the following changes:
    • Automatic grid = False
    • Line style = dotted
    • Label position = 0.0

imap_hammer_final.gif

The iMap window now displays the map and grid projection with dotted lines and the grid annotations on the edges:

 

 

 

 

Note
You can add a title and other annotations using the Text tool on the iMap tool bar.