# Surface Subsidence

Dear ABraun,

I created combined stack of only displacement band (1+2+…19), using this created one average displacement band using Band Math(dis1+dis2+dis3+…dis19)/19.
And then same way i created combined stack of only coherence band (1+2+…19). using this created one average coherence band using Band Math (coh1+coh2+coh3+…coh19)/19.

Then finally i stacked both of this bands.
properties of the displacement band (new_band_14), placed coherence band value (new_band_13_slv57_21Nov2017) >0.35 as shown in below figure.

final output

Is it correct ?

looks correct - good job!

Thank you ABraun.

Phase to Displacement
The unwrapped phase is now a continuous raster but not yet a metric measure. To convert the radian units into absolute displacements, the Phase to Displacement operator (under Radar > Interferometric > Products) is applied. It translates the phase into surface changes along the line-of-sight (LOS) in meters. The LOS is the line between the sensor and a pixel. Accordingly, positive values mean uplift and negative values mean subsidence of the surface (if the master image is the earlier acquisition date).
Copied from
InSAR Displacement Mapping
with ERS data
Issued April 2020
Andreas Braun.

Because if LOS is increase (means sensor to ground pixel distance increases (+ indication)) I’m getting subsidence (- indication) and vice versa.

Is it correct?

this depends on the order of yourr images. Which one is the master and which one is the slave?

For suppose master is 2014 January and slave is 2020 August. Then how can we define LOS (or upliftment and subsidence)?

if the master is the earlier date, negtive values indicate subsidence and positive ones indicate uplift.

Dear ABraun
I started processing interferograms (1+2, 1+2, 1+3 …) using these Graph builder in batch processing.

In this processing as it will (as you said) 1+1, 1+2, 1+3 … but i got 1+2, 2+2, 2+3, 2+4…(shown in below figure) how can use this for DInSAR processing.

now you can proceed with filtering, multi-looking, unwrapping, phase to displacement and terrain correction.

But please check the quality of the interferograms first.

But, In the above list (1+2, 2+2, 2+3, 2+4, 2+5…) which one i have to select as a master image?

there is no general rule for this. with 1+2 you capture the displacement based on a period of maybe 12 days, but with 2+5 this period is 36 days (if we assume 12 days between each subsequent pair).

Sometimes, longer periods result in more clear patterns, but they also suffer from higher decorrelation. On the other hand, it often depends on which incidents you want to analyze, e.g. if there was a specific date since something happened, so you place your image pairs around this incident.

If you want to understand the temporal dynamics of a longer time-span it is often good to add subsequent pairs (for high coherence), so 1+2, 2+3, 3+4 and then add up the displacements or visualize them over time in a graph. Check how this was done in this tutorial (slides are old but the last part on the multi-temporal analysis is still valid) https://eo-college.org/resource/insar_deformation/

Thank you ABraun.

stamps(2,2)

STAMPS: ########################################
STAMPS: ####### StaMPS/MTI Version 4.0b6 #######
STAMPS: ####### Beta version, Jun 2018 #######
STAMPS: ########################################

STAMPS: Will process patch subdirectories
psver currently: 1
psver now set to: 1

STAMPS: ########################################
STAMPS: ################ Step 2 ################
STAMPS: ########################################
STAMPS: Directory is PATCH_1

PS_EST_GAMMA_QUICK: Starting
PS_EST_GAMMA_QUICK: Estimating gamma for candidate pixels
GETPARM: filter_grid_size=50
GETPARM: filter_weighting=‘P-square’
GETPARM: clap_win=32
GETPARM: clap_low_pass_wavelength=800
GETPARM: clap_alpha=1
GETPARM: clap_beta=0.3
GETPARM: max_topo_err=20
GETPARM: lambda=0.0554658
GETPARM: gamma_change_convergence=0.005
GETPARM: gamma_max_iterations=3
GETPARM: small_baseline_flag=‘n’
Found look angle file
PS_EST_GAMMA_QUICK: n_trial_wraps=0.252487
PS_EST_GAMMA_QUICK: Initialising random distribution…
PS_EST_GAMMA_QUICK: 455435 PS candidates to process
PS_EST_GAMMA_QUICK: iteration #1
PS_EST_GAMMA_QUICK: Calculating patch phases…
Error using zeros
Requested 60459x155072x50 (1746.3GB) array exceeds maximum array size preference. Creation of arrays greater
than this limit may take a long time and cause MATLAB to become unresponsive. See array size limit or

Error in ps_est_gamma_quick (line 215)
ph_grid=zeros(n_i,n_j,n_ifg,‘single’);

Error in stamps (line 326)
ps_est_gamma_quick(est_gamma_parm);

while running stamps(2,2), i’m getting this above error. please give me solution.
Thank you.

how many patches did you select during mt_prep_snap?

Seems like the raster is excessively large…

I replace the ps_load_initial_gamma.m file in Stamps4.2b/matalb.
Then stamps(2,2) step is running nicely.
Thank you.

1 Like

interesting - thank you for reporting. I thought this was no longer necessary.

1 Like

stamps(6,6)

STAMPS: ########################################
STAMPS: ####### StaMPS/MTI Version 4.0b6 #######
STAMPS: ####### Beta version, Jun 2018 #######
STAMPS: ########################################

STAMPS: Will process current directory only

STAMPS: ########################################
STAMPS: ################ Step 6 ################
STAMPS: ########################################
STAMPS: Directory is 6_psiexport

PS_UNWRAP: Starting
Phase-unwrapping…
GETPARM: small_baseline_flag=‘n’
GETPARM: unwrap_patch_phase=‘n’
GETPARM: scla_deramp=‘n’
GETPARM: subtr_tropo=‘n’
GETPARM: tropo_method=‘a_l’
GETPARM: drop_ifg_index=
GETPARM: unwrap_hold_good_values=‘n’
PS_UNWRAP: Code to hold good values skipped
GETPARM: unwrap_time_win=730
GETPARM: unwrap_method=‘3D’
GETPARM: unwrap_grid_size=200
GETPARM: unwrap_gold_n_win=32
GETPARM: unwrap_prefilter_flag=‘y’
GETPARM: unwrap_gold_alpha=0.8
GETPARM: unwrap_la_error_flag=‘y’
GETPARM: unwrap_spatial_cost_func_flag=‘n’
GETPARM: max_topo_err=20
GETPARM: lambda=0.0554658
PS_UNWRAP: n_trial_wraps=0.261384
Resampling phase to grid…
Number of interferograms : 50
Number of points per ifg : 269037
Number of resampled points: 7915
Interpolating grid…
Number of unique edges in grid: 18636
Unwrapping in time-space…
Estimating look angle error (elapsed time=199s)
Using sequential daisy chain of interferograms
Smoothing in time (elapsed time=201s)
Unwrapping in space…
Processing IFG 1 of 50
Invalid file identifier. Use fopen to generate a valid file identifier.

Error in uw_stat_costs (line 159)

Error in uw_3d (line 163)
uw_stat_costs(options.unwrap_method,options.variance);

Error in ps_unwrap (line 235)
[ph_uw_some,msd_some]=uw_3d(ph_w(:,unwrap_ifg_index),ps.xy,day,ifgday_ix(unwrap_ifg_index,:),ps.bperp(unwrap_ifg_index),options);

Error in stamps (line 503)
ps_unwrap

Please tell me the solution for this error.

Thank you

After replacing the ps_load_initial_gamma.m file in matlab folder. It is working up to stamps (5,5) without any interruption.

After finishing, the stamps(5,5). i run this below command as shown in stamps manual.

ps_plot(‘w’)
Warning: MATLAB has disabled some advanced graphics rendering features by switching to software OpenGL. For
Color Range: -3.14159 to 3.14159 rad

ans =

Figure (1: w) with properties:

``````  Number: 1
Name: 'w'
Color: [0.9400 0.9400 0.9400]
Position: [672 479 560 420]
Units: 'pixels'
``````

Show all properties

While running stamps(6,6) i’m getting above posted error.
Thank you.

this looks like the case here where triangle was installed but the path was not correct in the config file. After you source the config file in the shell, you should be able to get the tool parameters when you type “triangle”. Please test.

Thank you so much ABraun… Its working