Gamma DIFF/GEO: Reference Manual

WSS_interp

ANSI-C program: WSS_interp.c

NAME
WSS_interp - ASAR Wide-Swath SLC complex image resampling using an offset polynomial model and  2-D SINC interpolation

SYNOPSIS
 WSS_interp <SLC-1> <SLC-2> <SLC1_par> <SLC2_par> <DIFF_par> <DIFF_par> <SLC-2R> <SLC2R_par>

<SLC-1> (input) ASAR Wide-Swath SLC_1 reference image
<SLC-2> (input) ASAR Wide-Swath SLC-2 image to be resampled to the geometry of the WSS SLC-1 reference image
<SLC1_par> (input) ASAR Wide-Swath SLC-1 image parameter file
<SLC2_par> (input) ASAR Wide-Swath SLC-2 image parameter file
<DIFF_par> (input) WSS DIFF/GEO parameter file containing polynomial offset model
<SLC-2R>  ASAR Wide-Swath SLC-2R coregistered to SLC-1
<SLC2R_par  (output) ASAR Wide-Swath SLC-2R image parameter file for coregistered image

EXAMPLE
WSS_interp 20030921.VV.IS2.SLC 20040208.VV.IS2.SLC 20030921.VV.IS2.SLC.par 20040208.VV.IS2.SLC.par 20030921_20040208.VV.IS2.diff_par 20040208.VV.IS2.rslc 20040208.VV.IS2.rslc.par

Use the range and azimuth offset polynomials in 20030921_20040228.VV.IS2.diff_par to resample 20040208.VV.IS2.SLC to the geometry of 20030921.VV.IS2.SLC. Output is in 20040208.IS2.rslc with parameter file 20040208.IS2.rslc.par.

DESCRIPTION
WSS_interp uses the polynomial offset model in the DIFF_par file to resample ASAR Wide Swath SLC into the geometry of a reference ASAR Wide Swath SLC image. Offsets are measured between MLI images produced from the ASAR Wide-Swath SLC data using multi_SLC_WSS. 

The Wide-Swath SLC data are produced from SCANSAR data and has a different format than strip-map mod SLC images. Each burst is processed into an SLC burst that is 48 lines long with 80 meter along-track azimuth pixel spacing with each point on the ground imaged by on average 3 bursts. Generating a pair of coregistered ASAR Wide-Swath SLCs requires the following steps:
  1. Generate MLI images from the Wide-Swath SLC data using  the ISP program  multi_SLC_WSS
  2. Create DIFF/GEO offset parameter file DIFF_par using create_diff_par
  3. Measure offsets between resampled MLI-2 and MLI-1 using ( offset_pwrm)
  4. Estimate offset polynomial coefficients using (offset_fitm)
  5. Resample the WS SLC data using WSS_interp using the offset polynomials stored in the DIFF_par file
  6. (OPTIONAL) Confirm lookup table offset correction and goodness of fit:
    1. Calculate an MLI image from the resample SLC-2R using the ISP program  multi_SLC_WSS
    2. Measure new offsets btween the MLI-2R and MLI-1 using DIFF program offset_pwrm. (use a new DIFF_par file)
    3. Generate new range and azimuth offset polynomials using DIFF program  offset_fitm 
    4. Analyze the new residual range and azimuth offset polynomials to confirm goodness of fit
    5. Use dis2SLC to confirm goodness of fit between resampled SLCs and the reference. The number of pixels to use for the image width is number of image pixels + 6. 24 bytes at the start of each line are use for the line header.

A 2D SINC interpolator is used in the resampling of the complex valued data. The interpolation takes into account  changes in the Doppler centroid both along-track and in slant range.  

SEE ALSO
create_diff_par, offset_pwrm, offset_fitm

© Copyrights for DIFF/GEO Documentation, DIFF/GEO Users Guide and DIFF/GEO Reference Manual by Gamma Remote Sensing, 2005.
UW, CW, last change 1-Mar-2006.