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Time series <off_par>
Added by Hui Luo about 6 years ago
Hi all
When dealing with time series, I'm confused about the offset parameter file <off_par> used.
Suppose we have 3 SLCs A B and C, and A and B are both coresgistered C as A.r/B.r/C and then we get 2 <off_par> as A_C.off and B_C.off.
If we want to generate the inteferogram of A and B under the A.r/B.r/C geometry.
SLC_intf A.r B.r A.rslc B.rslc <XX.off> A_B.int ....
So what the <XX.off> should be?
Not only inteferogram generation but the later steps such as phase_sim/create_diff_par, this off_par will also be used.
Thanks,
Hui
Replies (1)
OFF_par for different pairs for a stack of images coregistered to a common reference - Added by Charles Werner about 6 years ago
Dear Hui,
C is the geometric reference scene in your example. This means that A and B have
been coregistered to C.
The offset parameter files contain information on the number of looks, pixel
size, and region of the SLCS used to form the interferogram, as well as
parameters for the the offset determination.
Note however, that these days, the interferograms we process cover the entire
SLC frame, not some small section. The OFF_par had more importance when making
interferograms of only a small section.
specify that C is the geometric reference!!
$ phase_sim_orb
- Simulate unwrapped interferometric phase using DEM height and deformation
rate using orbit state vectors *** - Copyright 2017, Gamma Remote Sensing, v2.4 12-Jun-2017 clw ***
usage: phase_sim_orb <SLC1_par> <SLC2R_par> <OFF_par> <hgt> <sim_unw>
[SLC_ref_par] [def] [delta_t] [int_mode] [ph_mode]
input parameters:
SLC1_par (input) SLC parameter file of reference SLC-1
SLC2R_par (input) SLC parameter file of resampled SLC-2
OFF_par (input) ISP offset/interferogram parameter file
hgt (input) height relative to the WGS-84 elliposid in the same
geometry as the mosaic (meters, float, enter - for none)
sim_unw (output) simulated unwrapped interferometric phase
SLC_ref_par (input) SLC parameter file of the image used for geometric
coregistration (enter - for none)
def (input) LOS deformation rate map (meters/yr, float, enter - for none)
delta_t (input) interferogram time interval (days, required for
deformation modeling, enter - for none)
int_mode (input) interferometric acquisition mode:
0: single-pass mode (Tandem-X)
1: repeat-pass mode (default)
ph_mode phase offset mode:
0: absolute phase (default)
1: subtract phase offset that is a multiple of 2PI to improve
precision
You must supply Scene C as the SLC_ref_par. When calculating the simulated
phase, we actually calculate 2 baselines A-C and B-C and then subtract these to
get the Baseline AB.
Create an OFF_par for AB using the program create_offset so that the file exists
when doing the processing.
- Create and update ISP offset and interferogram parameter files ***
- Copyright 2015 Gamma Remote Sensing v5.3 clw/uw 10-Nov-2015 ***
usage: create_offset <SLC1_par> <SLC2_par> <OFF_par> [algorithm] [rlks] [azlks]
[iflg]
input parameters:
SLC1_par (input) SLC-1/MLI-1 ISP image parameter filename (reference)
SLC2_par (input) SLC-2/MLI-2 ISP image parameter filename
OFF_par (input/output) ISP offset/interferogram parameter file
algorithm offset estimation algorithm
1: intensity cross-correlation (default)
2: fringe visibility
rlks number of interferogram range looks (enter - for default: 1)
azlks number of interferogram azimuth looks (enter - for default: 1)
iflg interactive mode flag (enter - for default)
0: non-interactive
1: interactive (default)
just accept the defaults (non-interactive). The offset polynomial information in
the OFF_par is not used in the later processing steps such as phase_sim_orb and
SLC_diff_intf.
You will find that the contents concerned with the image size of the OFF_par
will be identical to AC and BC if you process the entire frame in each case.
Best regards,
Charles