ArcMap

Define Projection

Available with Advanced license.

Summary

Records the coordinate system information of the Input Coverage including any associated projection parameters, such as datum and spheroid.

It creates or modifies the Input Coverage's projection definition file (PRJ) that stores the projection parameters.

Learn more about how Define Projection works

Usage

  • Can be used if the input dataset or feature class does not have a projection defined. If the input dataset or feature class already has a projection defined, a warning will be raised but the tool will execute successfully.

  • To actually project the dataset or transform the datum or spheroid, you need to use the Project tool, which requires that your dataset have a PRJ file.

  • Define Projection will not change the coordinates of the output dataset. To project a dataset from one projection to another, you must use Project.

  • To find tables of predefined geographic coordinate system, projected coordinate system, and geographic (datum) transformations, see An overview of map projections.

Syntax

DefineProjection_arc (in_cover, projection_file)
ParameterExplanationData Type
in_cover

The coverage for which the projection information is being defined.

Coverage
projection_file

The name of a text file defining the input projection parameters.

File

Code sample

DefineProjection example (stand-alone script)

The following stand-alone script demonstrates how to define the projection on a global coverage. The coverage is stored in geographic coordinates. 

# Name: DefineProjection_Example.py
# Description: Defines the projection of a global coverage
# Requirements: ArcInfo Workstation

# Import system modules
import arcpy
from arcpy import env

# Set environment settings
env.workspace = "C:/data"

# Set local variables
inCover = "worldgrat"
projectionFile = "newgeo.prj"

# Execute DefineProjection
arcpy.DefineProjection_arc (inCover, projectionFile)

Environments

Licensing information

  • ArcGIS Desktop Basic: No
  • ArcGIS Desktop Standard: No
  • ArcGIS Desktop Advanced: Requires ArcInfo Workstation installed

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