INSPSN

Description

The INSPSN module unwraps the phase of all points where the bitmasks is set to one. The bitmask locations should correspond to persistent scatterers (stable targets) which are only marginally affected by temporal and geometric decorrelation. The module INSPSC can be used to generate a bitmask of persistent scatterer locations derived from a coregistered stack. The unwrapped phase at stable points can be utilized to accurately model the velocity of surface deformation and remove atmospheric artifacts from a stack of interferograms.

Parameters

inspsn(fili, dbic, filref, dbib, calwin, regufact, maxrd, filo, calbpsc)

Name	Type	Caption	Length	Value range
FILI*	str	Input file	1 -
DBIC*	List[int]	Database Input Channel	1 -	Default: 1
FILREF*	str	File containing bitmap layer	1 -
DBIB	List[int]	Bitmap Layer	0 -
CALWIN	List[int]	Calibration window size	0 - 2
REGUFACT	List[float]	The regularization factor	0 - 1	0 - Default: 0
MAXRD	List[int]	Max Radius to Connect PSCs	0 -
FILO*	str	Name of Output file	1 -
CALBPSC	str	Toggle Best PSC tilt processing	0 -

* Required parameter

Parameter descriptions

FILI

This parameter specifies the name of the input file containing the complex valued, unwrapped interferogram.

DBIC

This parameter identifies the complex valued input channel containing the layer to be unwrapped.

FILREF

This parameter specifies the name of the input file containing the bitmask. The size of the bitmask file should correspond to the size of the input file. If the input file contains the bitmask, FILREF and FILI can be identical.

DBIB

This parameter specifies the bitmask layer.

CALWIN

The size of the image window, in pixels and lines, centered on each best persistent scaterers as determined by INSPSC. In the window, all valid displacements are averaged, and the resulting value is used to obtain the correction associated with the given best persistent scaterer. The values of 1, 1, means that the exact value is used as the correction at each best persistent scaterer.

To define a square window, enter a single value, To define a rectangular window, enter two values. The window has the same size at all best persistent scaterers, based on the specified value or values.

If this parameter is not specified, the window will cover an area of 1000m x 1000m based upon the image sample sizes extracted from the metadata.

REGUFACT

This regularization parameter weights the residual norm against the solution norm. Its role is to find a balance between solutions overfit to the noisy measurements and solutions that are constrained too much.

If not specified, the default factor value of 0 reduces to the unregularized solution.

MAXRD

The maximum length in meters of the arc between connected PSCs to include in the unwrapping network. If blank, no arcs will be excluded based on length.

FILO

This parameter specifies the name of the PIX file to be generated which will contain the unwrapped values at the locations associated with the set values of the bitmask. If the input file is a deformation interferogram, the output is converted to displacement in the line of sight in meters, otherwise the output is written in radians. This file must not already exist.

CALBPSC

If input files contain "Best PSC" metadata, this option allows using that information to calibrate the unwrapped interferogram to the Best PSCs. 'YES', 'Y', or blank will calibrate the unwrapped interferogram using the Best PSC metadata. 'NO', 'N' will not calibrate the unwrapped interferogram.

Details

INSPSN generates a network connecting all bit masked points. The phase differences of these points are used to solve a series of linear equations to determine the unwrapped phase. The unwrapped phase values are written in radians. Unmasked points are set to the no data value.

INSPSN uses a triangulation method to generate a connected network of persistent scatters. The phase differences from the connected network are then used to solve a series of linear equations to determine the unwrapped phase (written in radians) at each persistent scatterer location. The remaining points (i.e. those not set by the bitmask) are set to the no data value. A consistency check is applied to the unwrapped phases.

Examples

Use the wrapped interferogram contained on the first channel of the input file to estimate the unwrapped phase (in radians) for all points set by the bitmask layer (2) of the reference file and write the result to the output file.

from pci.inspsn import *
fili = r"c:/Wrapped_phases.pix"        #file containing wrapped interferogram
dbic = [1]                             #channel with wrapped interferogram
filref = r"c:/PSC_points.pix"          #file containing bitmask
dbib = [2]                             #use bitmask layer 2
calwin = [3, 3]                        #average nine pixels around every point
regufact = [0.05]                      #use a weak regularization
maxrd = [1300]                           #do not unwrap along arcs longer than 1300 meters
filo = "c:/Unwrapped.pix"              #output containing unwrapped phase
calbpsc = ""                           #default PSC tilt processing
inspsn(fili, dbic, filref, dbib, calwin, regufact, maxrd, filo, calbpsc)
      

Use the wrapped interferogram contained on the third channel and the bitmask layer (4) of the input file to estimate the unwrapped phase (in radians) and write the result to the output file.

from pci.inspsn import *
fili = r"c:/Wrapped_phases.pix"        #file containing wrapped interferogram
dbic = [3]                             #channel with wrapped interferogram
filref = fili                          #input file contains bitmask
dbib = [4]                             #use bitmask layer 4
calwin = []                            #average 1kmx1km around every point
regufact = []                          #default no regularization
maxrd = [1300]                           #do not unwrap along arcs longer than 1300 meters
filo = "c:/Unwrapped.pix"              #output containing unwrapped phase
calbpsc = ""                           #default PSC tilt processing
inspsn(fili, dbic, filref, dbib, calwin, regufact, maxrd, filo, calbpsc)