INSTOPO

Description

INSTOPO adjusts the phase of a raw interferogram to compensate for flat-Earth and topographic effects.

Parameters

instopo(fili, dbic, filedem, filo)

Name	Type	Caption	Length	Value range
FILI*	str	Database input file name	1 -
DBIC	List[int]	Database input channel list	0 -	1 -
FILEDEM	str	Database DEM file name	0 -
FILO*	str	Database output file name	1 -

* Required parameter

Parameter descriptions

FILI

The name of the input interferogram created with the INSRAW algorithm.

DBIC

The layer or layers from the input interferogram to process. The default is to process only the first channel.

FILEDEM

The name of the file containing the digital elevation model (DEM). The DEM information must be in meters and stored in the first channel of the file.

FILO

The name of the file to which to write the phase-corrected interferograms. The file name you specify must not exist already.

Return Value

Returns: Program execution status

Type:  PCI_INT

The return value is 0.

This function returns only if it executes successfully; otherwise, it throws an exception.

Details

INSTOPO models the orbits of the reference and dependent files to calculate the required adjustment of the interferometric phase for systematic (flat-Earth) effects. When you specify a DEM, variations in interferometric phase caused by topography are corrected. The systematic flat-Earth and optional topographic corrections are adjusted for the nominal processing elevation, in meters, provided by the NominalLocation_Height metadata tag. If the nominal processing elevation is not available in the metadata, the surface of the ellipsoid is assumed.

The DEM elevations are resampled to the slant range of the reference file. For each slant-range pixel, the modified elevation, incident angle, and interferometric gradient are computed to calculate the flat-Earth and topographic-phase corrections. The NoData areas of the input file are not modified. If the DEM does not fully cover the area covered by the interferogram, the output for the nonoverlapping regions is processed as NoData.

If you do not specify a DEM, you can use the output to generate one. By doing so, the InSARContent metadata tag is set to TopographicInterferogram. When you specify a DEM, you can use the output to generate a deformation map. By doing so, the InSARContent metadata tag is set to DeformationInterferogram. The InSARContent metadata tag is read by the INSUNWRAP algorithm to determine the type of processing to apply.

If there are any residual fringes due to orbital error, you can correct them by running the INSADJUST algorithm.

Examples

The following example corrects a single-channel interferogram for flat-Earth effects, but does not remove topographic fringes. The output interferogram can be unwrapped by running the INSUNWRAP algorithm to generate a DEM.

from pci.instopo import instopo

fili    =  r"C:\MyProject\Single_channel_interferogram.pix"
dbic    =  []
filedem =  ""
filo    =  r"C:\MyProject\Topographic_interferogram.pix"

instopo(fili, dbic, filedem, filo)
      

The following example corrects a single-channel interferogram for flat-Earth effects and topographic fringes. The output interferogram can be unwrapped by running the INSUNWRAP algorithm to generate a deformation map.

from pci.instopo import instopo

fili    =  r"C:\MyProject\Single_channel_interferogram.pix"
dbic    =  []
filedem =  r"C:\MyProject\DEM.tiff"
filo    =  r"C:\MyProject\Deformation_interferogram.pix"

instopo(fili, dbic, filedem, filo)
        

The following example removes flat-Earth and topographic fringes from a multi-channel interferogram.

from pci.instopo import instopo

fili    =  r"C:\MyProject\Multi_channel_interferogram.pix"
dbic    =  [1,2,3,4]
filedem =  r"C:\MyProject\DEM.tiff"
filo    =  r"C:\MyProject\Multi_Channel_Deformation_interferogram.pix"

instopo(fili, dbic, filedem, filo)
        

Algorithm

Acknowledgements

The PCI Interferometric SAR (InSAR) project was funded in part by the Canadian Space Agency under the Earth Observation Application Development Program (EOADP) contract (9F043-130644/006/MTB), Application Development for Environmental Monitoring and Remediation.