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Warp From File


Transforms a raster dataset using an existing text file containing source and target control points.


Example of two-dimensional coordinate transformations


  • Warp is useful when the raster requires a systematic geometric correction that can be modeled with a polynomial. A spatial transformation can invert or remove a distortion by using polynomial transformation of the proper order. The higher the order, the more complex the distortion that can be corrected. The higher orders of polynomial will involve progressively more processing time.

  • The default polynomial order will perform an affine transformation.

  • To determine the minimum number of links necessary for a given order of polynomial, use the following formula:

    n = (p + 1) (p + 2) / 2

    where n is the minimum number of links required for a transformation of polynomial order p. It is strongly suggested to use more than the minimum number of links.

  • This tool will determine the extent of the warped raster and will set the number of rows and columns to be about the same as in the input raster. Some minor differences may be due to the changed proportion between the output raster's sizes in the x and y directions. The default cell size used will be computed by dividing the extent by the previously determined number of rows and columns. The value of the cell size will be used by the resampling algorithm.

    If you choose to define an output cell size in the Environment Settings, the number of rows and columns will be calculated as follows:

  • You can save your output to BIL, BIP, BMP, BSQ, DAT, Esri Grid , GIF, IMG, JPEG, JPEG 2000, PNG, TIFF, MRF, CRF or any geodatabase raster dataset.

  • When storing your raster dataset to a JPEG file, a JPEG 2000 file, or a geodatabase, you can specify a Compression Type and Compression Quality in the Environments.


WarpFromFile_management (in_raster, out_raster, link_file, {transformation_type}, {resampling_type})
ParameterExplanationData Type

The raster that you want to transform.

Mosaic Layer; Raster Layer

The name, location, and format for the dataset you are creating. When storing a raster dataset in a geodatabase, do not add a file extension to the name of the raster dataset. When storing your raster dataset to a JPEG file, a JPEG 2000 file, a TIFF file, or a geodatabase, you can specify a compression type and compression quality using environment settings.

  • .bilEsri BIL
  • .bipEsri BIP
  • .bmp—BMP
  • .bsqEsri BSQ
  • .dat—ENVI DAT
  • .gif—GIF
  • .jpg—JPEG
  • .jp2—JPEG 2000
  • .png—PNG
  • .tif—TIFF
  • .mrf—MRF
  • .crf—CRF
  • No extension for Esri Grid
Raster Dataset

The file containing the coordinates to warp the input raster.

Text File

Select a method for shifting the raster dataset.

  • POLYORDER0 This method uses a zero-order polynomial to shift your data. This is commonly used when your data is already georeferenced, but a small shift will better line up your data. Only one link is required to perform a zero-order polynomial shift.
  • POLYSIMILARITY This is a first order transformation that attempts to preserve the shape of the original raster. The RMS error tends to be higher than other polynomial transformations because the preservation of shape is more important than the best fit.
  • POLYORDER1A first-order polynomial (affine) fits a flat plane to the input points.
  • POLYORDER2A second-order polynomial fits a somewhat more complicated surface to the input points.
  • POLYORDER3A third-order polynomial fits a more complicated surface to the input points.
  • ADJUST This method combines a polynomial transformation and uses a triangulated irregular network (TIN) interpolation technique to optimize for both global and local accuracy.
  • SPLINE This method transforms the source control points precisely to the target control points. In the output, the control points will be accurate, but the raster pixels between the control points are not.
  • PROJECTIVE This method warps lines so they remain straight. In doing so, lines that were once parallel may no longer remain parallel. The projective transformation is especially useful for oblique imagery, scanned maps, and for some imagery products.

Choose an appropriate technique based on the type of data you have.

  • NEAREST Nearest neighbor is the fastest resampling method; it minimizes changes to pixel values since no new values are created. It is suitable for discrete data, such as land cover.
  • BILINEAR Bilinear interpolation calculates the value of each pixel by averaging (weighted for distance) the values of the surrounding four pixels. It is suitable for continuous data.
  • CUBIC Cubic convolution calculates the value of each pixel by fitting a smooth curve based on the surrounding 16 pixels. This produces the smoothest image but can create values outside of the range found in the source data. It is suitable for continuous data.
  • MAJORITYMajority resampling determines the value of each pixel based on the most popular value in a 3 by 3 window. Suitable for discrete data.

The Nearest and Majority options are used for categorical data, such as a land-use classification. The Nearest option is the default since it is the quickest and also because it will not change the cell values. Do not use either of these for continuous data, such as elevation surfaces.

The Bilinear option and the Cubic option are most appropriate for continuous data. It is recommended that neither of these be used with categorical data because the cell values may be altered.


Code sample

WarpFromFile example 1 (Python window)

This is a Python sample for the WarpFromFile tool.

import arcpy
     "\\cpu\data\raster.img", "\\cpu\data\warp_out.tif",
     "\\cpu\data\gcpfile.txt", "POLYORDER2", "BILINEAR")
WarpFromFile example 2 (stand-alone script)

This is a Python script sample for the WarpFromFile tool.

##Warp image with signiture file

import arcpy
arcpy.env.workspace = r"C:/Workspace"
arcpy.WarpFromFile_management("raster.img", "warp_output.tif", "gcpfile.txt", 
                      "POLYORDER2", "BILINEAR")

Licensing information

  • ArcGIS Desktop Basic: Yes
  • ArcGIS Desktop Standard: Yes
  • ArcGIS Desktop Advanced: Yes

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