Output extent

• The keyword used at the command line or in scripts for this environment setting is: Extent.
• Set this environment if your study area is only a portion of a larger dataset.
• The extent entered are assumed to be in the coordinate system in which the data is stored, even if the OutputCoordinateSystem environment is set.
• Extent uses keywords at the command line or in scripting. If you set extent using the environments dialog you will notice the keywords are represented with phrases.



Keyword	Dialog option	Description
MINOF	Intersection of Inputs	The minimum area common to all inputs; where all layers overlay. This is the default.
MAXOF	Union of Inputs	The maximum extent of all inputs; the combined extent of all inputs.
value	As specified below	User specified XMin, YMin, XMax, YMax values.
N/A	Default	The maximum extent of all inputs; the combined extent of all inputs. NOTE: This option is available only on the environments dialog.

• When you first specify the extent to be the same as a layer, the extent is read and set. The next time you open up environments, it will read "As specified below". The numbers come from the previously set layer, but the option reverts to "as specified below".
• Learn more about specifying general settings
• Learn more about environment settings
• Learn more about environment levels and hierarchy

In ModelBuilder

• In ModelBuilder, Extent will also show a list of variables. If you create a feature dataset, raster dataset, feature layer, raster layer, or extent variables in your model you will see these as options in the extent drop-down list. These choices are easily recognizable because they appear as either "Same as variable <name>" or "Same as layer <name>".
• The list will also show derived data in the drop down list. Derived data does not already exist before the model is executed and therefore can't be selected as the model extent. So if you are setting the extent for the entire model do not select derived data.
• You can selected derived data only if you are setting the extent for a single process and the derived data will be created before the process will execute. In your model diagram you will see a condition connector line appear that forces the model to first execute the process with the derived data element.
• In ArcGIS 9.2, extent is dynamic which allows for the additional selection of feature dataset, raster dataset, feature layer, raster layer, or extent variables. However, if you open the extent environment and click anywhere in the top/bottom/left/right input boxes the input will display As specified below and the extent will become static. The variable you had selected will no longer define the extent and the connector line will be automatically removed from your model. To make the extent dynamic again you will need to re-set the extent by selecting a drop-down list choice.

Command line examples

Extent MINOF
Extent '1 1 512 512'

Script example

import arcgisscripting
gp = arcgisscripting.create()

gp.workspace = "h:/workspace"
gp.toolbox = "SA"
gp.Extent = "MAXOF"
gp.Extent = "1 1 512 512"