Coregistered SLC stack for Envisat

Microwave Toolbox StaMPS
#1

I want to perform PSI using 6 Envisat ASAR images, I have performed coregistration, interferogram formation, topographic phase removal, phase filtering, geocoding, subsetting of my required area for each pair of images selecting the oldest image as master in each pair.
So, I have obtained 5 interferogram which has same master image and different slave image of different year of the same frame and I have subsetted each of the interferogram having using same geocordinates and pixel co-ordinates.
Now I want to export this interferograms from SNAP to StaMPS for PSI, but whenever I try to export they ask for one coregistered stack of SLC image and minimum 4 interferograms with elevation band.
I have tried stacking using create stack option the subsets of interferogram(gives error that cannot stack if image has phase band so only kept the coherence and elevation band), the phase filtered interferograms and even the interferograms without filtering and tried to use them as Coregistered stack of SLC and subsetted ineteferograms, filtered interferograms, interferograms without filtering respectively as input for PSI export as trial.That is, I performed 3 different trials with different type of inputs. But these don’t seem to work and I cannot pinpoint my problem. Please help me identify my problem and also how to solve it. As I cannot understand how to make Coregistered SLC stack for master and slave images.

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Multi-Temporal InSAR by SNAP
#2

PS processing needs large time-series to be able to compute the stability of a pixel and, regardless of your problem, I would say that 6 is clearly not enough for that purpose.

Besides that, you need for the StaMPS export:

  • the stack of all your envisat products (by coregistration)
  • the stack of all interferograms (check ‘add lat/lon band’ and ‘add elevation band’) for all products to be included
#3

Thank you for your reply.
Though i still have few confusions about the fact that if i try to stack the interferogram after applying terrain correction will it work?
Also, should i add both the stack of Envisat images formed using coregistration option and the stack of interferograms?
Is it the correct process to use the oldest image as master for every interferogram?or should i use the slave image of previous interferogram as master image next interferogram?

#4

for InSAR it is advisable to leave all data in slant geometry, so I wouldn’t recommend range doppler terrain correction. You should actually

  1. coregister all images
  2. perform interferogram generation (including lat/lon and dem bands)

add both products in the StaMPS export

Currently, snap only supports stacks with one master and multiple slaves (AB AC AD…)

#5

Thank you for the help.

#6

I exported successfully for StaMPS,thanks for helping me.
But I lack idea about how to further proceed in StaMPS to obtain PSI.Can you please suggest me the steps i need to follow to obtain PSI using StaMPS and Matlab in Windows 10 with 16GB RAM.

#7

The processing starts at chapter 6 of the manual: https://homepages.see.leeds.ac.uk/~earahoo/stamps/StaMPS_Manual_v3.1.pdf

But you need to compile stamps first and replace the scripts. Please have a close look here: About the STaMPS category

#8

thanks for the help.

#9

Is this stack is by Coregistration > Coregistration
or
through Coregistration > Stack tools> Create stack?

#10

Coregistration > Coregistration - generally for all products which are not yet projected.

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#11

@ABraun When I try to coregister the interferograms (with lat/lon and elev. band) I get the Error: [NodeId : Warp] The product “…” already contains a band withe the name ‘Intensity_null’
But I checked in side the folder- there is no such band by that name. Can you help?

#12

What data are you using and which steps did you apply?

#13

I aim to do PSI. For it I created a coregistered stack (Coregistration > Coregistration) of envisat subsets (on which I had not applied orbit files). that works fine.

But when I want to create coregistered stack (Coregistration > Coregistration) of the interferograms then the following error arises.
For generating interferograms- I have subset the images (also without applying any orbit files), then created interferograms (using the default values) and then topographic phase removal (with lat/lon an elvelation band output checked).

Note if i use the 'create stack" then there’s no error.

#14

how can you create the interferograms without coregistering?
I doubt that they will look good with simple stacking.

#15

Sorry I meant I have subset the images (also without applying any orbit files), then coregistered each pair, then created interferograms for each pair(using the default values) and then topographic phase removal (with lat/lon an elvelation band output checked).

#16

If all interferograms have the same master you can simply stack them, that is true.

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#17

Do you know @ABraun how I can do this in snappy?
I am facing this error RuntimeError: java.lang.NullPointerException

But actually i don’t know how to use master and slave image.

#18

I’m not very experienced with snappy, sorry.