Warp From File (Data Management)

Summary

Performs a transformation on the raster based on a link file, using a polynomial transformation. The link file contains the source and target control points.

Illustration

Usage

• 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 (1) 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:

  columns = (xmax - xmin) / cell size
  rows = (ymax - ymin) / cell size

• You can save your output to BIL, BIP, BMP, BSQ, DAT, GIF, Esri Grid, IMG, JPEG, JPEG 2000, PNG, TIFF, 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 within the Environment Settings.

Syntax

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

Parameter	Explanation	Data Type
in_raster	The input raster dataset.	Mosaic Layer; Raster Layer
out_raster	Output raster dataset. When storing the raster dataset in a file format, you need to specify the file extension: .bil—Esri BIL .bip—Esri BIP .bmp—BMP .bsq—Esri BSQ .dat—ENVI DAT .gif—GIF .img—ERDAS IMAGINE .jpg—JPEG .jp2—JPEG 2000 .png—PNG .tif—TIFF no extension for Esri Grid When storing a raster dataset in a geodatabase, no file extension should be added 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.	Raster Dataset
link_file	The link file that will be used to warp the raster. Each row in the input link file should have the following values, each delimited by a TAB: <Optional ID> <From X> <From Y> <To X> <To Y>.	Text File
transformation_type (Optional)	The geometric transformation type. POLYORDER0 —A zero-order polynomial is used 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. POLYORDER1 —A first-order polynomial (affine) fits a flat plane to the input points. This is the default. POLYORDER2 —A second-order polynomial fits a somewhat more complicated surface to the input points. POLYORDER3 —A third-order polynomial fits a more complicated surface to the input points. ADJUST —A transformation that optimizes for both global and local accuracy. It accomplishes this by first performing a polynomial transformation, then adjusting the control points locally, to better match the target control points, using a triangulated irregular network (TIN) interpolation technique. SPLINE —A transformation that exactly transforms the source control points to the target control points. This means that the control points will be accurate, but the raster pixels that are between the control points are not. PROJECTIVE —A transformation that can warp 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.	String
resampling_type (Optional)	The resampling algorithm to be used. The default is NEAREST. NEAREST —Nearest neighbor assignment BILINEAR —Bilinear interpolation CUBIC —Cubic convolution MAJORITY —Majority resampling 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 NEAREST or MAJORITY for continuous data, such as elevation surfaces. The BILINEAR option and the CUBIC option are most appropriate for continuous data. It is not recommended that BILINEAR or CUBIC be used with categorical data because the cell values may be altered.	String

Code Sample

WarpFromFile example 1 (Python window)

This is a Python sample for the WarpFromFile tool.

import arcpy
arcpy.WarpFromFile_management(
     "\\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.Warp_management("raster.img", "warp_output.tif", "gcpfile.txt", 
                      "POLYORDER2", "BILINEAR")

Environments

Compression, Current Workspace, Output CONFIG Keyword, Output Coordinate System, Extent, NoData, Pyramid, Raster Statistics, Scratch Workspace, Snap Raster, Tile Size

Licensing Information

ArcGIS for Desktop Basic: Yes

ArcGIS for Desktop Standard: Yes

ArcGIS for Desktop Advanced: Yes