After precisely geocoding your data and after aligning well your external DEM with your data,
you can uise this function (it's optional) to refine the coregistration using the external DEM.
The default coregistration process is in fact using a 2D polynomial to resample the data on the Master grid.
However, in particular in cases of high-resolution data over mountainous areas, if high normal baselines are present,
the geometric distorsion might be enough to cause decorrelation even for point-wise targets.
Be aware that if the DEM is not well aligned and/or its resulution/accuracy are too low, this process might worsen
the co-registration.
The software will not allow you to re-process this step simply by pressing this button multiple times.
If you want to re-process the coregistration refinement follow the steps below:
- run the "SLC data processing" module (from the "Select Dataset" window)
- check the directory contents (you will need your original SLC data to re-process the fine coregistration)
a - if you want to re-process a single image, pick it up from the "single image" menu
- press the set orbits button
b - if you want to re-process all images, set the orbits in update mode
- after the orbits are set in update mode, check the "all" flag
- exctract all slaves
- make sure NO "ovw" option is selected in the coregistration parameters
- run the coregistration (the sw will use coefficients previously processed -if available-)
- when the coregistration is done, close the window
- open the "site processing" module
- run the coregistration refinement again