ANSI-C program: offset_tracking.c
NAME
offset_tracking converts range and azimuth offsets files
to displacement map
SYNOPSIS
offset_tracking <offs> <snr> <SLC_par>
<OFF_par> <disp_map> [disp_val] [mode] [thres]
[poly_flag]
| <offs> | (input) range and azimuth offset estimates (fcomplex) |
| <snr> | (input) SNR values of offset estimates (float) |
| <SLC_par> | (input) SLC parameter file of reference SLC |
| <OFF_par> | (input) offset parameter file used in the offset tracking |
| <disp_map> | (output) range and azimuth displacement estimates (fcomplex)) |
| [disp_val] | (output) range and azimuth displacement estimates and SNR values (enter - for none) (text) |
| [mode] | flag indicating displacement mode: 0: displacement in range and azimuth pixels 1: displacement in meters in slant range and azimuth direction 2: displacement in meters in ground range and azimuth direction (default) |
| [thres] | SNR threshold to accept offset value (default from OFF_par) |
| [poly_flag] | flag indicating if trend calculated using offset
polynomials from OFF_par is subtracted: 0: do not subtract polynomial trend from offset data 1: subtract polynomial trend from offset data (default) |
EXAMPLE
offset_tracking 1352_1610.offs 1352_1610.snr 1352.slc.par
1352_1610.off 1352_1610.disp_map 1352_1610.disp_val 2 6.5
1
Converts the input offset fields (*.offs) to an offset map (*.disp_map) which has the same dimension as the original reference SLC image.
DESCRIPTION
offset_tracking converts the input offset fields
(*.offs) to an offset map (*.disp_map) which has the same
dimensions as the original SLC reference image.
The binary offsets file (*.offs) contains offsets in SAR image pixels (of the reference image) in fcomplex format. The real parts correspond to range offsets and the imaginary parts to azimuth offsets. The positions of the offset estimates are defined by the starting range and azimuth positions and the range and azimuth steps, as documented in the offset parameter file. Only offsets with a quality value (SNR) above an indicated threshold are used. For offsets with an SNR below the threshold and for missing estimates (previously discarded) the offset map values are set to (0.0,0.0).
The threshold 2D range and azimuth offsets map (*.disp_map) is in fcomplex format. The real parts correspond to range displacements and the imaginary parts to azimuth displacements. The file size and positions corespond to those of the reference SAR image.
Different modes are supported. The offsets can be expressed as displacement in range and azimuth pixels (0), or as displacement in meters in slant range and azimuth direction (1), or as displacement in meters in ground range and azimuth direction (2, default mode).
The offset polynomials defined in the offset parameter file can either be subtracted from the offset values (poly_flag=1) or not subtracted (poly_flag = 0). The idea of subtracting the offset polynomials is that the polynomials shall reprosent overall registration offsets, while the offset map shall only contain offsets related to surface displacements.
SEE ALSO
typedef_ISP.h, OFF_par, offset_fit, offset_pwr, offset_SLC, offset_pwr_tracking, offset_SLC_tracking, create_offset.