Parameter descriptions
FILREF
The name of the file to use as the reference data set. The file must contain single-look complex (SLC) data. The pixels of the dependent file must align one-to-one with the pixels of the reference file. FILREF can be either in the original slant-range projection, or resampled to the dependent file, or in the projection of a third (i. e. common) reference file.
DBIC_REF
The list of channel numbers from the reference file.
FILI
The name of the file to use as the dependent data set. The file must contain single-look complex (SLC) data. The pixels of the dependent file must align one-to-one with the pixels of the reference file. FILI can be either in the original slant-range projection, or resampled to the reference file, or in the projection of a third (i. e. common) reference file.
DBIC
The list of channel numbers in the dependent file. The number of channels must match identically with the number in the reference file.
FLSZ
The filter size, in pixels, of the adaptive Lee filter to apply. You specify the filter as n x n, where
n is an odd integer greater than or equal to five.
FILO
The name of the output file to which to write the raw interferograms. The file will contain the same number of pixels and lines as the reference file and the number of channels you specified. Nonoverlapping areas will be processed as NoData. The file name you specify must not already exist.
Details
The dependent file must be coregistered and aligned (by running the INSCOREG algorithm) pixel-by-pixel with the reference file. Both the reference and resampled dependent file must be in single-look complex format (SLC), and the beam modes must be the same. The output file will contain the same number of pixels and lines as the reference file with the number of complex valued channels you specified. Each output channel represents the interferometric product of the corresponding input channels.
Note: The value of DBIC_REF and DBIC need not be identical.
Viewing unfiltered interferograms in CATALYST Professional
Focus
In
Focus, the default interpretation of complex values is
Intensity. If you opted not to use the adaptive Lee filter, the interferometric phase is computed without filtering (i.e. 1x1), but the resulting interferogram will have the magnitude (and intensity) associated with the minimum 5x5 filter. This is to avoid generating an interferogram with a constant coherence (amplitude) value of one. If you want to view unfiltered interferograms in
Focus, open the file, and then do either of the following:
- On the Maps tab, right-click the unfiltered interferogram you want to display, point to Data Interpretation, and then click Phase in radians or Phase in degrees, as applicable.
- On the Files tab, expand Rasters, right-click the channel you want, point to View, and then click As Amplitude and Phase.
Examples
Generate a nonfiltered, single-channel interferogram between the reference file (in its original projection) and the resampled dependent file (generated by INSCOREG) using the default values.
from pci.insraw2 import insraw2
filref = r"C:\MyProject\Reference_File.pix"
dbic_ref = []
fili = r"C:\MyProject\Resampled_File_1.pix"
dbic = []
flsz = []
filo = r"C:\MyProject\Interferogram_1.pix"
insraw2(filref, dbic_ref, fili, dbic, flsz, filo)
Generate a nonfiltered, single-channel interferogram using the resampled file (from the previous example) as the reference file and a third file already coregistered to the resampled file (by INSCOREG). Note: The input files "Resampled_File_1" and "Resampled_File_2" and the output files "Interferogram_1" and "Interferogram_2" are in the same slant range projection as the original reference file. This technique can be used to coregister multiple files to a common slant range projection.
from pci.insraw2 import insraw2
filref = r"C:\MyProject\Resampled_File_1.pix"
dbic_ref = []
fili = r"C:\MyProject\Resampled_File_2.pix"
dbic = []
flsz = []
filo = r"C:\MyProject\Interferogram_2.pix"
insraw2(filref, dbic_ref, fili, dbic, flsz, filo)
Generate a filtered interferogram using a seven-by-seven adaptive Lee filter.
from pci.insraw2 import insraw2
filref = r"C:\MyProject\Reference_File.pix"
dbic_ref = []
fili = r"C:\MyProject\Resampled_Dependent_File.pix"
dbic = []
flsz = [7]
filo = r"C:\MyProject\Adaptive_Filtered_Single_Channel_Interferogram.pix"
insraw2(filref, dbic_ref, fili, dbic, flsz, filo)
Generate a filtered, multi-channel interferogram using a seven-by-seven adaptive Lee filter. The output file will contain four interferograms. Each output layer (n) is defined by the interferogram between the reference layer [DBIC_REF(n)] and the dependent layer [DBIC(n)].
from pci.insraw2 import insraw2
filref = 'Multi_Pol_Reference_File.pix'
dbic_ref = [1,2,3,4]
fili = 'Multi_Pol_Resampled_Dependent_File.pix'
dbic = [1,2,3,4]
flsz = [7]
filo = 'Adaptive_Filtered_Multi_Channel_Interferogram.pix'
insraw2(filref, dbic_ref, fili, dbic, flsz, filo)
from pci.insraw2 import insraw2
filref = r"C:\MyProject\Multi_Pol_Reference_File.pix"
dbic_ref = [1,2,3,4]
fili = r"C:\MyProject\Multi_Pol_Resampled_Dependent_File.pix"
dbic = [1,2,3,4]
flsz = [7]
filo = r"C:\MyProject\Adaptive_Filtered_Multi_Channel_Interferogram.pix"
insraw2(filref, dbic_ref, fili, dbic, flsz, filo)
Algorithm
The following formula is the complex-valued correlation coefficient of the input reference and dependent files, where w
i is the weight of the adaptive Lee Filter, I
k
ref and I
k
dep are the complex values of the references and coregistered dependent data for the k
th channel listed in reference and dependent files, respectively, * is the complex conjugate, and N is the size of the adaptive filter. If N = 1, then |γ
raw| = 1.
The magnitude of the correlation coefficient is the coherence of the interferogram. Typically, a higher coherence represents a higher-quality interferogram. The magnitude of a complex number is computed as follows:
The phase of the correlation coefficient is the relevant wrapped interferometric phase. The phase of a complex number is computed as follows:
