Dear Ram,

Thanks for your interest

I installed snaphu and performed phase unwrapping for the filtered interferogram 

now I have already a DInSAR but in slant range units 

I need to convert this slant (phase difference) to metric units (Displacements)

Regards

Hi Reda. Once you have unwrapped slant range phase values. It needs to be converted into slant range metric units using displacement = lambda*phi/ 4*pi. where phi is the slant range displacement phase which you derived using phase unwrapping. pi is 3.14. lambda is the wavelength of the SAR signal, like for X, its 3.1 cm, C its 5.6 cm and so on. If you apply this formula, you will get the slant range motion in metric units.

If you want to convert the slant range into absolute up/down motion (as you are looking for crustal uplift/subsidence), then you should consider the local incidence angle of the scene. Local incidence angle constitutes of the global incidence angle of the satellite, while acquiring your scene, and the slope of the terrain. Be cautious. 

You need to ultimately tie your final product with some stable points where you consider no motion or the points where you know some uplift/subsidence information from GPS or other field survey methods. This is necessary for accuracy assessment. 

This in total will you give you the product.

Regards.

Saurabh

Hi Reda,

I see from the attached image in your question, you are using the SNAP Sentinel-1 Toolbox. In the current version, there is a tool to convert the unwrapped phase to displacement. It is located under 'Radar' > 'Interferometric' > 'Products' > 'Phase to Displacement'.

Note that this is 'Line-of-sight' (LOS) displacement towards the sensor, not vertical displacement, for which you need both an ascending and descending scene.

Regards,

Alisdair

You need to unwrap the phase and then there's a relation between unwrapped phase, incidence angle and wavelength that gives displacement. For details go through this-

https://www.researchgate.net/deref/http%3A%2F%2Fdx.doi.org%2F10.1117%2F12.2326267?_sg%5B0%5D=cAyirgxsTf17GYPdNhk30BjBs5VX7-LjFz1VdCwVKu2NscNuYhYulPbaK09LinyuG-rtopWYjze_L2aKT74S4t6iww.4XuhOTk22B2uL4nFUxamVWH_rGIKb19Vp7V36s5rOalEweToX3ycnVNQgsu5ysw_xcnkcxxMrzwdjB9VhYHjZA

Dear all,

what do you think about the idea to use DInSar to detect vertical displacement of gravel-bed rivers due to flood events?

The question is deliberately generic so you can express your own view ;) !

Thanks Daniele