Transform (Coverage)

License Level:BasicStandardAdvanced

Summary

Moves all features in a coverage based on a set of from and to control points.

Learn more about how Transform works

Illustration

Transform illustration

Usage

Syntax

Transform_arc (in_cover, out_cover, {transform_type})
ParameterExplanationData Type
in_cover

The coverage whose coordinates are to be transformed.

Coverage
out_cover

The name of an existing coverage containing destination tics. The features from the input coverage will be transformed into this coverage.

Coverage
transform_type
(Optional)

The type of coordinate transformation to be performed:

  • AFFINEPerforms an affine transformation. At least three tics are required to define this transformation. If only two tics are matched, a similarity transformation will be applied. The AFFINE equations use six parameters.
  • PROJECTIVEPerforms a projective transformation. This requires a minimum of four tics to define the transformation. The projective transformation is only used to transform coordinates digitized directly off high-altitude aerial photography or aerial photographs of relatively flat terrain, assuming there is no systematic distortion in the air photos. PROJECTIVE uses eight parameters.
  • SIMILARITYPerforms a similarity transformation. At least two tics are necessary for this transformation. This transformation is also known as a Helmert, orthogonal, two-dimensional linear conformal, or four-parameter transformation.
String

Code Sample

The following stand-alone script demonstrates how to use the Transform tool on a digitized coverage. First it creates an empy output coverage based on a template coverage. The template has tics and a defined projection. The empty output coverage is named roads. Then it transforms the digitized road features into the empty roads coverage.

# Name: Transform_Example.py
# Description: Transforms digitized road features into a new output coverage
# Requirements: ArcInfo Workstation

# Import system modules
import arcpy
from arcpy import env

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

# Set local variables
inCover = "roads_dig"
outCover = "C:/output/roads"
transformType = "AFFINE"

# Create the empty output coverage
arcpy.Create_arc(outCover, "citylim")

# Execute Transform
arcpy.Transform_arc(inCover, outCover, transformType)

# Print the RMS error
print arcpy.GetMessage(4)

Environments

Related Topics

Licensing Information

ArcGIS for Desktop Basic: No
ArcGIS for Desktop Standard: No
ArcGIS for Desktop Advanced: Requires ArcInfo Workstation installed
3/3/2014