AUTOSHIFT

Description

AUTOSHIFT shifts the position of an image by modifying its extents to ensure pixel alignment with a reference image. It is assumed that both images have a misalignment of only a few pixels and were acquired using the same viewing geometry. AUTOSHIFT prepares the images used as input to any of the coherent change detection algorithms functions. To co-register non-complex SAR images, it is recommended that you run ORTHO instead.

Parameters

Name	Type	Length	Value range
Input: Input complex SAR image *	Raster port	1 -
Reference: Reference complex SAR image *	Raster port	1 -
Output: Output shifted SAR image *	Raster port	1 -
Radius	Integer	0 - 1	Default: 16
Tiles X	Integer	0 - 1	Default: 4
Tiles Y	Integer	0 - 1	Default: 4

* Required parameter

Parameter descriptions

Input: Input complex SAR image

Specifies the name of the input image file to be shifted. The specified image must have the same georeferencing and pixel size, and at least some overlap with the reference image file.

The input image must be a data set that has already been imported into the PCIDSK (.pix) format by SARINGEST, or it may be the key file name of any GDB-supported POLSAR data set in its distribution format. The specified image must have the same georeferencing and pixel size, and at least some overlap with the reference image file.

Reference: Reference complex SAR image

Specifies the name of the file that contains the reference image data. This reference image must have the same geocoding and pixel size as the input test image file.

Output: Output shifted SAR image

Specifies the name of the output file that is created. This file will contain the same number of channels as the specified input channels.

The specified file must not already exist.

Radius

Specifies the distance, in pixels, in the X- and Y-directions over which the search for the best match between the reference and test image will be conducted. The value must be equal to or greater than the maximum offset between the images, in pixel units.

Tiles X

Specifies the number of tiles into which the overlap area will be divided, in the X-direction;. The tiles should all contain valid image data values (non-background pixels).

Tiles Y

Specifies the number of tiles into which the overlap area will be divided, in the Y-direction;. The tiles should all contain valid image data values (non-background pixels).

Details

AUTOSHIFT shifts a test image by modifying its geocoding extents to guarantee pixel alignment with the reference image. To preserve the original data, no resampling is applied to the test image file. The offset is computed based on the highest correlation of complex and/or intensity values of all pixels in the search window. This function supports any polarimetric (single, dual, full polarimetric) data set from all acquisition modes. The function is NoData-aware; which means any pixel values defined as 'NoData' in the metadata will be ignored. The output image file retains all the metadata from the input test image file.