GAMMA Interferometric Point Target Analysis Software (IPTA): Reference Manual

phase_sim_pt

NAME
phase_sim_pt - simulate unwrapped interferometric phase (single record or all records)

SYNOPSIS
phase_sim_pt <plist> <pmask> <pSLC_par> <ppos> <itab> <rec_num> <pbase> <phgt> <psim_unw> [pdef] [ph_flag] [bflag]

<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)
<pbase>	(input) stack of baseline parameters (binary)
<phgt>	(input) point data stack of terrain height (meters, float, single record, enter - for none) NOTE: if - is entered for both phgt and pdef, then the output simulated phase will all be 0.0 since there are no valid points. A value of 0.0 in the phgt file represents "no data"
<psim_unw>	(output) point data stack of simulated unwrapped interferometric phase (float)
[pdef]	(input) point data stack of LOS deformation rate (m/day, float, single record, enter - for none)
[ph_flag]	phase model flag 0: unflattened (default) 1: flattened 2: height + deformation phase, relative to ref. layer
[bflag]	baseline flag 0: use initial baseline (default) 1: precision baseline

EXAMPLE
phase_sim_pt pt pmask pSLC_par - itab - pbase phgt psim_unw - 0 0

Simulates the unwrapped interferometric phase (unflattened) based on the provided terrain heights and (initial) baseline information for all interferogram layers listed in the itab. No deformation is included in the simulation.

phase_sim_pt pt pmask pSLC_par -itab 3 pbase phgt psim_unw pdef 0 0

Simulates the unwrapped interferometric phase (unflattened) based on the provided terrain heights, (precision) baseline information, and the indicated deformation rate for all records of the itab. A linear deformation with time (i.e. constant deformation rate) is assumed in the model.

DESCRIPTION
phase_sim_pt simulates unwrapped interferometric phases considering terrain heights and a temporally constant deformation rates. This can be done for a single record of the itab or all records. The coordinates of the points considered are defined in the point list. The optional point mask file (in point data format) indicates for each point if it is valid (1, i.e. considered) or not valid (0, excluded).

Information required for the reference SLCs of the indicated interferometric pair(s) is provided in the stack of SLC parameter files. Optionally, interpolated point position coordinates can be used instead of the integer coordinates from the point list. Interferometric pairs are defined in the itab, a text file with a table associating interferogram stack records with pairs of SLC stack records. For each pair (line of the itab) the baseline parameter stack pbase contains a record with the related baseline parameters including the initial baseline, precision baseline, and phase constant.

The input terrain heights in meter (m) are also provided as a point data stack. This stack has a single record only (height is the same for all interferometric pairs). In an early stage of an IPTA investigation the heights are typically retrieved from an existing DEM. The heights in point data format can be obtained from 2-D height data using the program data2pt. Later on the heights may be improved based on the interferometric data, for example by adding the height corrections obtained with the def_mod_pt or multi_def_pt to the original heights. If the phase of deformation alone is to be simulated, the height file can be ommitted and the effective height set to 0 by entering a - in the argument list.

Optionally, temporally constant deformation rates can be considered in the simulation. The inputdeformation rates in meter per year (m/year) are also provided as a point data stack. This stack has a single record only (deformation rate is the same for all interferometric pairs, i.e. constant over time). In an early stage of an IPTA investigation the deformation rate is typically not modeled. Later on linear deformation rates as obtained with def_mod_pt or multi_def_pt can be considered.

Simulated unwrapped interferometric phases are calculated for each valid point of the point list. Valid points are points with a non-zero height value and a non-zero point mask value (if provided). Note that if both the height file and deformation rate file are both entered as - then the output will be all 0.0.

A ph_flag permits selecting if the unwrapped phase of the 0: unflattened, 1: flattened , or 2: phase due to the terrain height and deformaton, shall be generated. The phase flattening uses a simpler phase model for the ellipsoidal phase than option 2. Option 2 should be used if you want to subtract the phase term to terrain height that has been determined by performing a regression. Another bflag permits to selecting between using the initial or the precision baseline model in the pbase stack.

To display the simulated interferometric phase images contained in the point data stack the the program ras_data_pt can be used to rapidly display the phase as points using a raster image (Sun Raster or bmp format) as background. Alternately programs pt2data or pt2d can be used to convert the point data to 2d filled raster format data that can then be displayed using conventional display programs such as disrmg.

OPTIONS
To add or subtract atmospheric phase delay terms available in a point data stack to the simulated unwrapped phases the programs lin_comb_pt (single records) and sub_phase_pt (single or all records) can be used.