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Name | Type | Caption | Length | Value range |
---|---|---|---|---|
FILI* | String | Input complex SAR image | 1 - 192 | |
FILREF* | String | Reference complex SAR image | 1 - 192 | |
DBIC | Integer | Input complex SAR image channels | 0 - 4 | |
FILO* | String | Output Wishart change metric raster | 1 - 192 | |
WINSIZE | Integer | Window size (pixels) | 0 - 1 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 17 | 19 | 21 | 23 | 25 | 27 | 29 | 31 | 33 Default: 5 |
MONITOR | String | Monitor mode | 0 - 3 | ON, OFF Default: ON |
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FILI
Specifies the name of the input file that contains the test SAR image data.
This 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 file.
FILREF
Specifies the name of the file that contains the reference SAR image data.
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.
DBIC
Optionally specifies the list of input channels to be processed. The specified channels must exist for both the input and reference images, and must be comparable; that is, they must have the same data type and polarization. By default, all channels from the input test and reference file are used to compute the change.
Ranges of channels or segments can be specified with negative values. For example, {1,-4,10} is internally expanded to {1,2,3,4,10}. When you are not specifying a range in this way, only 48 numbers can be specified explicitly.
FILO
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 direction of change is inferred by visual inspection of the output.
The specified file must not already exist.
WINSIZE
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.
MONITOR
The program progress can be monitored by printing the percentage of processing completed. A system parameter, MONITOR, controls this activity.
Available options are:
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CCDWISH uses Wishart statistics to test the equality of two complex covariance matrices that are assumed to follow a Wishart distribution. When the backscatter coefficients are very close, but either the phase or the correlation coefficient between the co-polarization have changed, the Wishart test statistic is much more sensitive to the differences than test statistics based only on the intensity. In other words, CCDWISH may highlight changes that are not detected by CCDINTEN.
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.
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This example uses two Radarsat-2 Fine QuadPol images created by SARINGEST to measure the changes between September 19th and September 25th, using Wishart statistics.
EASI>FILI = 'C:\Data\rsat2_FQ15_sep19.pix' ! input image file name EASI>FILREF = 'C:\Data\rsat2_FQ15_sep25.pix' ! reference image file name EASI>DBIC = ! use all channels to detect change EASI>FILO = 'C:\Data\ccdwish_sep19_sep25.pix' ! output file name EASI>WINSIZE = 5 ! use a 5x5 processing window EASI>run CCDWISH
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Conradsen, K.; Aasbjerg, A.; Schou, J.; Skriver, H.; "A Test Statisitc in the Complex Wishart Distribution and its Application to Change Detection in Polarimetric SAR Data" IEEE Trans. Geosci Remote Sensing, 41, no. 1 (2003): 4-19.
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