ps_plot velocity

Hello all,
seeking explanation why velocity is different for
ps_plot(‘v-d’,1,0,0,[1:3,7:8],‘ts’), and
ps_plot(‘V-D’,‘ts’)

and what would be the difference in normal velocity plot ps_plot(‘v’) and with time-series ps_plot(‘v’, ‘ts’).

results attached.

Thanks in advance.

the “ts” flag does not change the output, it simply offers the option to click in the map and extract a time-series plot of a group of scatterers.

The larger value range of the first map could result from a higher impact of outliers in the data (only 5 interferograms are averaged instead of 8).

But I wonder why your displacement map is basically a representation of topography. Did you apply topographic phase removal in the preprocessing? It does not look reasonable as it is now to be honest.

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Thank for reply @ABraun
Yes i applied topographic phase removal while processing interferograms in SNAP (preprocessing).
I had 40 images so I made 4 patches of 10 images in each group.
Isn’t is bcoz in one result it is including 39 interferogram based velocity and in other only 5 are consider (including i didn’t filter the outliers, few interferograms have baseline over 80).

I didn’t know how much interferograms you had in total. So the discrepancy between 5 and 39 makes it even more plausible that the average velocity of the 5 ones has more outliers than the entire stack.

yess, The ps_info says:

ps_info
1 02-May-2018 89 m 47.592 deg
2 14-May-2018 8 m 47.107 deg
3 26-May-2018 -8 m 47.975 deg
4 07-Jun-2018 15 m 41.210 deg
5 19-Jun-2018 17 m 40.813 deg
6 01-Jul-2018 96 m 40.657 deg
7 13-Jul-2018 104 m 40.560 deg
8 25-Jul-2018 52 m 42.128 deg
9 06-Aug-2018 30 m 47.377 deg
10 18-Aug-2018 -36 m 46.719 deg

yess just checked, biggest outliers total 5 (more than 80 m) 2 are in this subset [1:3,7:8].
plus the area is prone to landslides (Himalayan region).
Does mean velocity of 39 interferograms i.e. -28.6 mm/yr to 28.7mm/yr makes sense?? please suggest.

that entirely depends on the study area. For landslides this is too low.

A good indicator is to plot small areas using the “ts” flag and check if the displacement is linear or noisy.

ps_info does not show outliers, the metric information is the length of the perpendicular baseline.

Dear @ABraun thank you so much for your time and valuable comments.

Dear @ABraun, The sentence “Using the ‘V-D’ option (rather than ‘v-d’) forces the use of single master interferograms for the estimation, even for SB or combined processing” in Chapter 7, StaMPS/MTI Mannual (version 4.1b), what does the meaning of “single master interferograms for the estimation” if I use the SBAS-InSAR method, but in fact, there are more than one master image in SBAS-InSAR method, Thank you for your help.