CCDPHASE

Description

CCDPHASE measures change based on the average coherence (over a specified window size) between two co-registered single-look complex SAR images. Coherence values will range between zero and one, where areas of change will have coherence values close to zero (that is, they are incoherent) while unchanged areas will have higher values (that is, will be coherent).

Parameters

Name	Type	Length	Value range
Input: Input complex SAR image *	Raster port	1 -
Reference: Reference complex SAR image *	Raster port	1 -
Output: Output phase change metric raster *	Raster port	1 -
Window Size	Integer	0 - 1	3 | 5 | 7 | 9 | 11 | 13 | 15 | 17 | 19 | 21 | 23 | 25 | 27 | 29 | 31 | 33 Default: 5

* Required parameter

Parameter descriptions

Input: Input complex SAR image

Specifies the test SAR image input layers.

The data must be a complex SAR image in scattering matrix format (symmetrized or non-symmetrized) and it must have the same georeferencing, pixel size, and viewing geometry as the reference image.

Reference: Reference complex SAR image

Specifies the reference SAR image layers.

The data must be a complex SAR image in scattering matrix format (symmetrized or non-symmetrized), and it must preserve the same structure as the input test image. This file must have the same georeferencing, pixel size, viewing geometry, bit depth, matrix representation, and calibration type as the specified input image.

Output: Output phase change metric raster

Specifies the name of the output file that is created. The output file will consist of the overlap area, and four channels that describe:

• the intensity value (or sum of intensities) of the input test data
• the intensity value (or sum of intensities) of the reference data
• the absolute value of the intensity ratio (written in decibels) between the test and reference average coherence
• the change, as percentiles, ranked from 0% (no change) to 100% (maximum change)

The direction of change is inferred by visual inspection of the output.

The specified file must not already exist.

Window Size

Optionally specifies the size of the square window that is moved over the images. All of the pixels in the window are averaged together for the value of the center pixel. The window size value must be an odd integer between 3 and 33. The default value of 5 defines a processing window of 5 pixels by 5 lines.

Details

CCDPHASE performs change detection based on phase information. It computes the intensity and polarimetric coherence value for each pixel in the overlap area, and determines the magnitude of the average coherence value. Change is determined based on the ratio of the computed total power for each pixel, to the magnitude of the average coherence value of the images. The computed change is written to cumulative percentiles, where negative values represent a "loss" and positive values represent a "gain" with respect to the reference image.

Both the input and the reference images must have been ingested through SARINGEST and must overlap. It is recommended that you check the pixel alignment (or run AUTOSHIFT) before computing the change. The input layers and reference layers must be comparable on a corresponding basis (for example, the first layers from each image must have the same polarizations).