Gamma ISP: Reference Manual

SLC_interp

NAME
SLC_interp - SLC resampling using 2-D SINC interpolation. Range and azimuth offset functions are polynomials stored in the ISP offset/interferogram parameter file

SYNOPSIS
SLC_interp <SLC-2> <SLC1_par> <SLC2_par> <OFF_par> <SLC-2R> <SLC2R_par> [loff] [nlines]

<SLC-2>	(input) SLC-2 image to be resampled to the geometry of the reference SLC-1 image
<SLC1_par>	(input) SLC-1 ISP image parameter file
<SLC2_par>	(input) SLC-2 ISP image parameter file
<OFF_par>	(input) ISP offset/interferogram parameter file
<SLC-2R>	(output) SLC-2 resampled into the reference geometry of SLC-1 (fcomplex)
<SLC2R_par>	(output) ISP image parameter file for resampled SLC-2R
[loff]	offset to starting line of interferogram (relative to SLC-1) (default=0)
[nlines]	number of SLC lines to process (default=to end of file)

EXAMPLE
SLC_interp 1610.slc 1352.slc.par 1610.slc.par 1352_1610.off 1610.rslc 1610.rslc.par

DESCRIPTION
SLC_interp registers SLC-2 to the reference geometry, that is the geometry of SLC-1.

A 2D SINC interpolator is used in the resampling of the complex valued data. The registration uses the bilinear coregistration offset polynomials for range and azimuth offset (as a function of range and azimuth) of the ISP offset/processing parameter file. To determine the offset polynomials use the programs offset_pwr, offset_SLC, and offset_fit are used. No spectral filtering is applied during the registration. Such filtering is applied during the interferogram calculation.

The coregistration of multiple SLC images to the same (reference) geometry has advantages in particular when several interferometric pairs are investigated. Due to the fact that the 2 SLC are coregistered no resampling/interpolation step is required. To coregister multiple SLC images the programs there are different possibilities. The registration offset function is determined using The resampling of the SLC to the reference geometry is then completed using the program SLC_interp.

SLC_interp has been updated to adapt to changes in the Doppler centroid along-track. This is especially applicable to the processing of long strips (>200 km) of Radarsat data where the Doppler centroid changes by more than 100 Hz/frame.

No multi-look intensity images are produced from the two SLC images. Coregistered multi-look intensity images in the identical geometry as the interferogram can be generated from the coregistered SLC images using the program multi_look. The parameters [lbegin] and [nltot] should nominally not be changed from the default values since the starting line and number of lines are not recorded in the SLC-1 parameter file. The primary intent of SLC_interp is to resample the SLC-2 image to the geometry of SLC-1. If a only an interferogram from a segment of the SLC images is desired, then use the program SLC_copy to extract the segment from SLC-1, before using SLC_interp and SLC_intf.

Display of the images can be carried out by ISP programs for complex data. Complex images can be displayed or saved as SUN raster or BMP files using the programs disSLC, dis2SLC, rasSLC.