as mentioned in Fialko 2001 for 3 D displacement from InSAR, a linear system of equations should be solved for each pixel :
1.Two equations from Ascending and Descending Orbits
[Un Sin φ – Ue Cos φ] Sin θ + Uu Cos θ + δlos = dr ……….. (1)
Where,
φ … The azimuth of the satellite heading vector (positive
clockwise from the North)
θ … The radar incidence angle at the reflection point
dr … The LOS displacement at the reflection point
δlos … Is the relative measurement error
2.
One equation for the Azimuthal Offset from the descending orbit
Un Cos φ + Ue Sin φ + δazo = dazo ………………….……….. (2)
my question is how to obtain dazo from an unwrapped differential interferogram.
Have a look into the paper of Joughin et al. 1998 I have attached. Though it explains how to tetermine the 3D flow vector of an ice-flow by using ERS-interferometry, the principle should be the same as in your case.
SARscape
http://www.exelisvis.com/ProductsServices/ENVIProducts/ENVISARscape.aspx
http://www.sarmap.ch/page.php?page=sarscape
offers you both amlpitude /speckle tracking and Multuple Aperture Interferometry (MAI)
http://web.stanford.edu/group/radar/people/noa_thesis.pdf
tools and workflows to derive both LOS and along-track (azimuth) displacement components from SAR data from any spaceborne sensor.
Dear Reda, for azimuth offsets you asked, you have to go for amplitude/offset/pixel tracking method. (All are same). They simply measure the horizontal shift in each pixel position between the two images by matching the intensities of the pixels. Getting 3d measurements can be done by combining as. and ds. pass interferometric measurements or you can do the same with as. and ds. offset tracking results as said by @peter. For offset tracking you can go through http://eprints.whiterose.ac.uk/747/1/murrayt1.pdf
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