ANSI-C program: base_ls_pt.c
NAME
base_ls_pt - least squares baseline estimation using terrain
heights (single record or all records)
SYNOPSIS
base_ls_pt <plist> <pmask> <pSLC_par>
<ppos> <itab> <rec_num> <punw>
<phgt> <pbase> [ph_flag] [bc_flag] [bn_flag]
[bcdot_flag] [bndot_flag] [bperp_min]
| <plist> | (input) point list (int) |
| <pmask> | (input) point data stack of mask values (uchar, set to - to accept all points) |
| <pSLC_par> | (input) stack of SLC/MLI parameters (binary) |
| <ppos> | (input) point data stack of interpolated point target positions (fcomplex, enter - to use plist coordinates) |
| <itab> | (input) table associating interferogram stack records
with pairs of SLC stack records (ascii) (line entries are: pSLC_rec1 pSLC_rec2 itab_rec_num switch_flag) |
| <rec_num> | record number to process (default -: all records) |
| <punw> | (input) point data stack of unwrapped interferometric phases (float) |
| <phgt> | (input) point data stack of terrain heights (float) |
| <pbase> | (input/output) stack of baseline parameters (binary) |
| [ph_flag] | restore range phase ramp (default=0: do not restore 1: restore) |
| [bc_flag] | cross-track baseline component estimate (0:orbit derived 1:estimate from data, default=1) |
| [bn_flag] | normal baseline component estimate (0:orbit derived 1:estimate from data, default=1) |
| [bcdot_flag] | cross-track baseline rate estimate (0:orbit derived 1:estimate from data, default=1) |
| [bndot_flag] | normal baseline rate estimate (0:orbit derived 1:estimate from data, default=0) |
| [bperp_min] | minimum perpendicular baseline required for L.S estimation (m, default= 10.) |
EXAMPLE
base_ls_pt testsite.plist testsite.pmask testsite.ppar -
testsite.itab - testsite.punw testsite.phgt testsite.pbase
0
Estimation of precision baselines for each interferometric pair listed in the itab using a non-linear least squares error analysis with unwrapped interferometric phases and height values at each point of the point list.
base_ls_pt testsite.plist testsite.pmask testsite.ppar - testsite.itab 5 testsite.punw testsite.phgt testsite.pbase 0
Estimation of precision baselines for record 5 of the point data stacks using a non-linear least squares error analysis with unwrapped interferometric phases and height values at each point of the point list.
INSTALLATION
Source code base_ls_pt.c in ./IPTA/src, executable version
base_ls_pt in ./IPTA/bin
DESCRIPTION
base_ls_pt supports the estimation of precision baselines using
point data stacks of unwrapped interferometric phases and known
terrain height values.
In the IPTA stacks of baseline parameters in binary format are used to organize the baseline information of sets of interferometric pairs. Pairs are defined in the itab, an ascii file with a table associating interferogram stack records with pairs of SLC stack records. For each pair (line of itab, record of point data stacks) the stack of baseline parameters contains a record with the related baseline parameters which are the same parameters as used in the baseline parameter file, i.e. initial baseline, precision baseline, and phase constant.
The estimated precision baselines (in TCN coordinates) are written to the related record in the stack of baseline parameters, the binary format used to store baseline information of stacks of interferograms. Either a single record or all records can be considered. To consider all records indicate - instead of a record number. Record numbers start with 1.
The points considered in the least squares fit are the points defined through the point list and the related point mask. Furthermore, points with a NULL (0.0) for the unwrapped phase or the terrain height are excluded from the fit.
The computed baselines are used in the simulation of the orbital phase trend and the topographic phase and in the conversion of interferometric phase values to terain heights.
Attention needs to be used concerning the idea to provide unwrapped phases corrected for the atmospheric delay and thereby to improve the fit. The baseline related phase error tends to end in the "atmospheric phase term", as it is also low frequency in the spatial domain and random in the temporal domain. Consequently, this will prevent the program from making the right correction for the baseline.
On the command line it is possible to activate/deactivate the modification of the phase constant and the individual components of the baseline model. The along track baseline component is asumbed to be 0 in any case.
Optionally, interpolated point position coordinates can be used instead of the integer coordinates from the point list.
For very short baselines the solution tends to get instable because of the neglectable influence of the topographic height on the phase. To avoid problems a minimum perpendicular baseline (e.g. 20m) can be set. For shorter baselines the precision baseline is set to the initial baseline estimate.
Other programs to manipulate stacks of baseline parameters include base_orbit_pt and base_par_pt. base_orbit_pt supports the initial baseline estimation from orbit state vectors. base_par_pt supports conversions between conventional baseline parameter files (ascii) and the IPTA stacks of baseline parameters (binary).
OPTIONS
none.
SEE ALSO
base_orbit_pt, base_par_pt, baseline_file, ipta.h.