Time-Series of Offset-Tracking for Glacier

Dear all,

As I checked the offset-tracking tool of SNAP for the glacier application, I found it so useful in monitoring of the glacier movement. I would like to know it is possible to do the time-series processing of offset-tracking method for glacier using SNAP or not?!

Best regards,
Sayyed

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Dear Falahfakhri,

Yes I know and also I reviewed the tutorial file provided by RUS service. I mean discussion about the scientific aspect of time-series offset-tracking of glacier movement. For example, we can suppose a master and slave like PS or SBAS technique and finally, get the mean velocity of movement or not?!

Best regards,
Sayyed

The offset-tracking measurements are essentially the same as InSAR measurements in that they are relative motion between two dates. The big difference is that offset tracking can often be done all relative to a single master date, unlike InSAR that can have loss of coherence or too much motion when a single master is used. If you can do all your offset-tracking measurements with a single master, then the time-series analysis is almost trivial. You can simply divide the measurements by the time interval to get mean velocity.

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Thank you so much for your nice conclusion. On the other hand, we can see that the offset-tracking will be applicable wherever we have a high rate of displacement like glacier or some especial earthquakes, which is not possible using the InSAR processing as good as the offset-tracking method. Yes?

Glacier-surfaces are not stable in the longer term, so correlations are lost because the trackable features disappear/change. Short temporal baselines work better in this situation too.

Good point. I work with rocks and soil that move in volcanoes, earthquakes and slow-moving landslides, and those surfaces often remain stable for long periods.

The pixel offsets are extremely helpful for large earthquakes where the ground surface moves too much for InSAR measurements, especially near the fault.

Sorry, you mean the single master processing is not also good for glacier movement? We lose correlations due to only a high-range of movement or changing the appearance of glacier sheets?

Hi Everyone,

I processed two S1A GRDH images for checking the movement of a glacier. The dates of images are 2019-08-17 and 2019-06-06. Using the SNAP to process by offset-tracking method, I got the legend as follows:

legend

Now, I confused about the rate and value of movement so that in this legend, the unit is in m/day but I only used two images with a temporal baseline of 71 days. Could anybody please guide me to describe the legend the SNAP software give us after processing?

Best regards,
Sayyed