Kazi
January 5, 2019, 3:55pm
#1
Hi,
ABraun
January 5, 2019, 4:42pm
#2
This is already discussed in several topics. Please directly address remaining questions there.
If you have ascending and descending interferograms, then you can calculate two components of the ground displacement. The LOS directions of ascending and descending Sentinel-1 orbits make it possible to estimate the East component and a mixture of the Up component and the North component.
You will need to do the phase unwrapping and conversion to displacement first. I don’t think there is any function in SNAP to do the complete calculation of the components, but you can get an approximate calc…
according to my understanding, the equation is just approximating the vertical elevation change. In fact, it is still largely representing the change of surfaces along the line of sight. There is no simple way retrieving it from a single InSAR image pair (confirmed by mengdahl here ). johngan nicely explained the difference here .
A comparison between the formula and the phase to displacement module is given here - they are nearly the same.
This was discussed this in several topics:
Differen…
Hi,
When doing measurements with SAR sensor to identify movements on the ground, we can resolve only one surface displacement vector. What the satellite measures is the distance between the satellite sensor and the ground but we cannot say that the ground was moved horizontally or vertically using only one satellite orbit (ascending or descending). If you want, we can make the assumption that the ground was moved vertically (we cannot be certain for that). SAR is much more sensitive to vertic…
By combining LOS displacement values of both ascending and descending directions you can calculate the actual direction with the Pythagoras theorem.
But differentiating between horizontal and lateral movement is hard to do.
SAR is measuring displacement in Line-Of-Sight. It is not possible to project that single measurement onto lateral or vertical without making extra assumptions about the direction of the actual movement. If you have two different LOS using ascending and descending data you will be able to solve the direction of actual movement without extra assumptions.