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iTool User's Guide: Working with Maps |
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A map projection establishes the axis type and coordinate conversion mechanism for mapping points on the earth's surface, expressed in latitude and longitude, to points on a plane, according to one of several possible map projections.
You can apply a map projection before or after you import image or contour data into the iMap tool. To do so, select Operations Map Projection. This command opens the Map Projection dialog, shown in Figure 15-1.
You can apply a map projection to another iTool as well. If you do, the tool will adapt to expose iMap functionality, including the iMap operations and the Map panel.
Table 15-1 shows the common projection properties.
In addition to these properties, the following properties (Table 15-2) become available depending on the selected projection:
Note The map projection properties are normally taken from the currently selected dataspace. However, in the Operations Browser, the map projection properties are registered on the operation itself. Changing these properties in the Operations Browser will have no affect on the currently selected dataspace. If the Show Dialog property is set to False and then the Map Projection operation is activated, the projection properties will be copied directly from the Map Projection operation onto the currently selected dataspace. |
Note Each projection has default longitude and latitude limits. If you have not modified one of these limits (the longitude and latitude minimum and maximum properties), the Map Projection operation will automatically use its default limit. However, if you have modified one of these limits, the Map Projection operation will use either your desired limit or the default limit, whichever is smaller. |
IDL Online Help (March 01, 2006)