"No Triangles Found" error upon smallbaselineAppy.py --dostep quick_overview

[Lincoln Olayta]

Good Day to everyone!

I'm Lincoln from the Philippines, and I'm currently trying to use MintPy to present time series from the Sentinel-1 InSAR data of Taal Volcano (processed using ISCE). I'd like to ask what are the causes of this error I've encountered while following the step-by-step method of smallbaselineApps.py tutorial. Any help would be appreciated, thanks a lot!!

Attached herewith is the error encountered. As well as the modified template file. Kindly inform me if there are files required to be seen for the assessment of the error. Thank you!


L. Olayta

[Yunjun Zhang]

Hi Lincoln,

The quick_overview is an auxiliary step and no other steps rely on it (if I remember it right). You should be able to continue to run the other steps one by one.

To help diagnose this error, could you attach the following two information?

1. run smallbaselineApp.py without --dostep and attach the full printout message so I could see what happened before this step.

2. it seems like the input stack of interferograms might not be able to form triplets. To confirm this, could you run info.py inputs/ifgramStack.py --date and attached the output here?

Yunjun

[Lincoln Olayta]

Thank you for your quick reply, Mr. Zhang!

I tried your suggested steps. Here are the results:

1. I tried running the smallbaselineApps.py as is, with only my modified template (smallbaseline_SENT1TAAL) for directories. The error persisted, attached herewith is the printed out text file of the outputs. (smallbaselineApp_usingmodifiedtemplate.txt)

2. By info.py inputs/ifgramStack.py --date, you mean ifgramStack.h5 (?), if so, here's the result:

Thank you so much for your help, and I'm sorry if this is such a rookie error. Thanks again!

Regards,

LPO. 

[Yunjun Zhang]

Hi LPO,

Your ifgramStack file has a sequential network with one connection, thus, no interferogram triplets can be formed from these existing interferometric pairs, resulting in the error you have. Since the quick_overview is not an essential step and the rest is not dependent on this step. I have changed the alert level from exception to warning here. Thank you for bringing this to our attention. Update your code and you should be able to continue without breaks.

On the other hand, the small baseline approach grabs its strength from the network redundancy, as shown in section 6.3 in my 2019 paper. You might want to add more interferograms (by increasing the number of connections while running stackSentinel.py from ISCE/topsStack).

Yunjun