Output extent
Release 9.3 Last modified December 17, 2008	Print all topics in : "General settings"

Defined area of interest for results from running tools. In the case of feature data, all input features to a tool that pass through the area of interest will be included in the calculation. For raster data, results from running tools will be contained within the extent set.

The extent is a rectangle, specified by identifying the coordinates of the window in map space.

Usage tips

• 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 extents 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 box, you will notice the keywords are represented with phrases.
  



Keyword	Dialog box 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 box.



• 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, a raster dataset, a feature layer, a 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 reset the extent by selecting a drop-down list choice.
  

Command line syntax

An overview of the command line window

Extent <MINOF | MAXOF | value>

Parameters	Explanation	Data type
<MINOF| MAXOF | value>	Specifies the extent of the study area. 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)—Specifies the minimum and maximum extent values: Left—XMin value Right—XMax value Bottom—YMin value Top—YMax value	String

Data types for geoprocessing tool parameters

Command line examples

Extent MINOF
Extent '1 1 512 512'

Scripting syntax

An overview of scripting in geoprocessing

Extent (study_area)

Parameters	Explanation	Data type
MINOF | MAXOF | value (Required)	Specifies the extent of the study area. 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)—Specifies the minimum and maximum extent values: Left—XMin value Right—XMax value Bottom—YMin value Top—YMax value	String

Data types for geoprocessing tool parameters

Script example

import arcgisscripting
gp = arcgisscripting.create()

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

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