Map calculation

Dialog box

Map calculation can be used to perform calculations with raster maps. In the dialog box, type a MapCalc expression. For more information on the operators and functions that can be used, refer to Map Calculation. You can also type your map calculation expressions on the command line of the Main window.

Dialog box options:

Expression:	Type a MapCalc formula, for example Map1+Map2 Mind: You must use single quotes around object names which start with a digit, contain spaces or contain one of the following special characters ` ~ ! @ # $ ^ & ( ) - + = [ ] { } ; ' , . . Example: 'My Map1' + 'My Map2'
Output raster map:	Type a name for the output raster map.
Defaults:	Click this button to obtain a default domain. When the default domain is a value domain, you also obtain defaults for the value range and precision of the output map. You can also click this button to obtain defaults again after you changed the default domain, value range or precision.
Domain:	Accept the default domain, or select or create your own output domain.
Value range:	If the output map uses a value domain, accept the default value range, or specify your own range of possible values in the output map.
Precision:	If the output map uses a value domain, accept the default precision of output values, or specify your own precision.
Description:	Optionally, type a description for the output map. The description will appear in the status bar of the Main window when moving the mouse pointer over the map in a Catalog, and in the title bar of a map window when the output map is displayed. If no description is supplied, the output map will use its own definition as description.

When you click the Show button, the dependent output map will be defined, calculated and shown. When you click the Define button, the dependent output map will only be defined; if necessary, the map will be calculated later, for instance when the map is opened to be displayed.

Tip:

When working with value maps, you can generally accept the default system domain Value. You only need to select or create a user-defined value domain when the values have a specific meaning for which you have or want to create a meaningful representation.