Geoprocessing tool reference > Data Management toolbox > Projections and Transformations toolset > Tools
Define Projection (Data Management) |
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Release 9.2
Last modified November 29, 2010 |
Print all topics in : "Tools" |
Records the coordinate system information for the specified input dataset or feature class including any associated projection parameters, datum and spheroid. It creates or modifies the feature class's projection parameters.
Usage tips
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This tool supports coordinate transformation using either of two projection systems. It can be used to define a feature class as a spherical coordinate system with angular units (such as Geographic) or a planar coordinate system with linear units. Most geoprocessing tools assume you have a planar, two-dimensional feature class. So if your feature class is in a geographic coordinate system in Decimal Degrees (DD, angular units), use the Project tool to project your feature class to any suitable projected coordinate system in linear units (meters or feet).
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This command can be used if the input dataset or feature class does not have a projection defined. If the input dataset or feature class has a projection defined, a warning will be raised but the tool will execute successfully.
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The coordinate system information of the input is created or modified by this tool. No separate output feature class will be created.
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If the input dataset or feature class doesn't have a projection defined, the coordinate system will be listed as Unknown on the dialog box.
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If the input dataset or feature class has a coordinate system defined, use the Project tool to modify it.
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Use the Spatial Reference Properties dialog box to select a coordinate system definition from either an existing definition list or from another dataset or to create a new coordinate system definition.
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All standalone geodatabase feature classes will be in the same coordinate system. All feature classes in a geodatabase dataset will be in the same coordinate system. The coordinate system for a geodatabase dataset should be determined as it's created. Once it contains feature classes, its coordinate system can't be changed.
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For more information on geographic transformations, see Geographic transformation methods.
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The environment setting that affects this tool is: configKeyword, extent, outputCoordinateSystem, scratchWorkspace, and workspace.
Command line syntax
An overview of the Command Line window
DefineProjection_management <in_dataset> <coor_system>
| Parameter | Explanation | Data Type |
| <in_dataset> |
Name of dataset or feature class whose projection is to be defined. |
Feature Layer | Geodataset |
| <coor_system> |
Name of the coordinate system to be applied to the input dataset or feature class. |
Coordinate System |
Command line example
DefineProjection_management c:\streams.shp 'Coordinate Systems\Geographic Coordinate Systems\Africa\Adindan.prj'
Scripting syntax
About getting started with writing geoprocessing scripts
DefineProjection_management (in_dataset, coor_system)
| Parameter | Explanation | Data Type |
| in_dataset (Required) |
Name of dataset or feature class whose projection is to be defined. |
Feature Layer | Geodataset |
| coor_system (Required) |
Name of the coordinate system to be applied to the input dataset or feature class. |
Coordinate System |
Data types for geoprocessing tool parameters
Script example
import arcgisscripting
gp = arcgisscripting.create()
gp.workspace = "c:/Workspace"
gp.toolbox = "management"
coordsys = "Coordinate Systems/Geographic Coordinate Systems/North America/North American Datum 1983.prj"
gp.defineprojection("counties.shp", coordsys)