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

temp_mod_sim_pt

ANSI-C program: temp_mod_sim_pt.c

NAME
temp_mod_sim pt  - Simulate temperature dependent differential phase for a stack of interferograms given the model parameters

SYNOPSIS
temp_mod_sim_pt <plist> <pmask> <SLC_tab_temp> <itab> [pdph_dtemp] [pph_offset] [pph_model]

<plist> (input) point list (int)
<pmask> (input) point data stack of mask values (uchar, set to - to accept all points)
<SLC_tab_temp> (input) table of SLC filenames, SLC parameter filenames, and temperature values (C) (text)
                 SLC        SLC_par    Temperature C
<itab> (input) table associating interferogram stack records with pairs of SLC stack records (text)
                 pSLC_rec1  pSLC_rec2  itab_rec_num  switch_flag
[pdph_dtemp] (input) derivative of phase w.r.t. temperature for each point (radians/degree C, float)
[pph_offset] (input) phase offset of linear regression of phase w.r.t. temperature (radians, float) (enter - for none)
[pph_model] (output) linear model for the phase due to temperature difference for each interferogram layer (radians, float) (enter - for none)

EXAMPLE

temp_mod_pt pt - SLC_tab_temp itab pdh_dtemp - pph_mod

This command uses a specially formatted list of the SLC_tab_temp file containing  the average scene temperatures to calculate a model for temperature dependent phase for differential interferograms.

DESCRIPTION

This program uses the output phase sensitivity with respect to temperature and phase offset from program temp_mod_pt. The program temp_mod_pt performs a linear regression on the residual interferometric phase with respect to the difference in scene temperatures for the days when the two SLC images were acquired. The slope of the linear regression is the derivative of the phase with respect to temperature difference and the phase constant is the phase when the temperature difference is 0.

The SLC_tab_temp has an additional third column with the average scene temperature in degrees C near to the time when the SLC data were acquired. An example of the SLC_tab_temp used in an example is shown below:

20071230.rslc  20071230.rslc.par  8.0
20080110.rslc  20080110.rslc.par 13.0
20080121.rslc  20080121.rslc.par  9.0
20080212.rslc  20080212.rslc.par  8.0
20080223.rslc  20080223.rslc.par 11.0
20080305.rslc  20080305.rslc.par  8.0

The third column of the SLC_tab_temp file is read by temp_mod_pt to determine the scene temperature. The SLC images used in the stack of interferograms is specified in the itab file and the residual unwrapped interferometric phase after removal of height related phase and tropospheric phase is stored in the pres file. Each layer in the pres file is the differential interferometric phase for interferogram using SLCs in the SLC_tab. The program temp_mod_pt prints out the temperature and date data for each interferogram. A section of the table for the first 6 interferograms in the stack of  a test example is shown below:

interf #SLC-1  #SLC-2   Date-1      Date-2     Temp-1   Temp-2   Diff-Temp
**************************************************************************
    1     40      1     2010 6 8   2007 12 3   21.000    8.000   -13.000
    2     40      2     2010 6 8   2008 1 10   21.000   13.000    -8.000
    3     40      3     2010 6 8   2008 1 21   21.000    9.000   -12.000
    4     40      4     2010 6 8   2008 2 12   21.000    8.000   -13.000
    5     40      5     2010 6 8   2008 2 23   21.000   11.000   -10.000
    6     40      6     2010 6 8   2008 3 5    21.000    8.000   -13.000

Input to the program consists of the following data and parameters

  1. plist    IPTA point list with the range and azimuth coordinates of the points, see plist file format
  2. pmask    IPTA pmask file. This file is an unsigned byte file set to 1 where a point is to be considered and 0 where not. Entering a "-" assumes all points are accepted in the input point list
  3. SLC_tab  SLC_tab with the addition of a third column with nominal temperature in the area of the scene preferably close to the time of the data acquisition. 
  4. itab     interferogram table. This is a text file with 4 columns that specifies the interferograms. The first two columns are references to entries in the SLC_tab, see itab file format
  5. pdh_dtemp    This is estimate of the derivative of the interferometric phase with respect to temperature difference  (radians/degree) assuming a linear dependence. The linear regression is performed for each accepted point in the stack and is obtained using program temp_mod_pt.
  6. pph_offset   This is the intercept of the linear regression of phase with respect to temperature difference (radians). When it is not provided, it is not included in the model calculation. When using the pdh_dtemp from a multi-reference set to simulate the phase of a single-reference stack, pph_offset should be omitted and set to "-".
Output from the temp_mod_sim_pt is the temperature dependent phase model for each layer
  1. pph_model    Temperature dependent phase model values (radians). Evaluated for each point and each interferogram.
The output of the phase model for interferogram with index k is given by:

where   is a phase constant and  is the derivative of phase with respect to temperature difference for each point with index i.

To apply  temp_mod_pt very early in the processing,  a multi-reference stack is typically used that includes pairs with relatively short baselines and possibly also small changes in temperature (but not 0).  When using a multi-reference stack with temp_mod_pt, it is recommended to set the phase offset to 0.0 (modes 0, 2).  The temperature sensitivities from the multi-reference stack point phase regressions can be used to model the temperature in the single-reference interferogram stack. The itab of the single reference stack must be supplied on the command line of the program. Entering "-" for the name of the phase offset sets the value in the phase model to 0

SEE ALSO

ipta.h, SLC_tab format, itab file format, plist file format, expand_data_pt, def_mod_pt, temp_mod_pt

© Copyrights for Documentation, Users Guide and Reference Manual by Gamma Remote Sensing, 2014.
UW, CW last change 5-May-2014.