I need the steps applied to create the interferogram in SNAP 6.0 and the phase developed in SNAPHU

Oliverius · November 7, 2019, 4:20am

these are the steps:

Step 1. Open data

Step 2. Corregistration

Step 3. Interferogram formation

Step 4. Tops derbust

Step 5. Topographic phase removal (DinSAR)

Step 6. Goldstein phase filtering

Step 7. Multilooking

Step 8. Snaphu export

Step 9. Unwrapping phase with SNAPHU

Step 10. Import unwrapping with SNAP

Step 11. Unwrapped phase result

Step 12. Phase conversion in displacement

Step 13. Range doppler terrain correction

Step 14. The file obtained is exported as a tiff for procesing in QGIS 3.10

From the steps applied i ask for your opinion and the answer according to your experience for the following questions:

a). If the water does not discriminate in the interferogram, how do you eliminate the effect of coherence in slow waters?
b). If the band can identify areas identified by the potential for water erosion and wind erosion in areas without vegetation cover?
c). If the interval time of 1 year can be taken as a reference for surface deformation or subsidence?

Regards,

Paau, Oliver
ingenieriaenambienteyenergia@gmail.com
Guatemala, Centro America.

ABraun · November 7, 2019, 7:19am

First of all, your steps look alright to me, the order is fine.

Water areas decorrelate within a few seconds, getting inteferometric information here is nearly impossible. Some discussions on this: Sentinel 1A_reservoir water level extraction

these are non-coherent processes and therefore cannot be monitored by DInSAR, please also see mengdahl’s comment on this here.

It depends a bit on your study area. The risk of decorrelation is quite high for c-band over such a long period. Especially if you have lots of vegetation, you will be left with only small areas of high coherence and the unwrapping between these areas (no fringes here) will produce weird results.
Another aspect is the amount of displacement you expect within two images. If it exeeds the wavelength (about 5 cm for C-band) you will also lose control over the absolute amount, because the phase shift is no longer resolvable.