GAMMA Questions

Hi Sonya,

which method did you use to unwrap your interferogram? May we also have a look on this? The big question is: are the island area and the big area connected in your interferogram or not? If so, how big/reliable is the connection? Did you carefully check if there any phase jumps? My guess is that you need to correct the big area of a multiple of 2 PI. You may use the command bridge to achieve that.

Cheers, Julia

My guess is it didn't unwrap correctly over the river...
If you haven't tried this yet: change your unwrapping parameters (maybe a smaller/weaker filter also helps) so that the unwrapping can't go across the river by itself, then bridge manually.
Jackie

Hi Julia, hi Jackie,
I used branch-cut method and I did use the bridge command to unwrap step by step over the river.
Thanks!
Sonya.

Sonya, can you show us your original interferogram, than maybe the
flagfile, the rastree file and the bridge file you used? Also where is
you original seedpoint located? In the correct island area or outside?

As far as I understand the bridging only helps if the areas are not unwrapped already (it can not "force" a correct unwrapping). So make sure you have no branches crossing the river

Do the hgt-file-values agree well with your GCPs? If yes, or if they all show a similar shift, it could be just a reference issue, e.g. depending on where you started the unwrapping. I am not sure if the hgt-file shows phase jumps - maybe try to display it in colors as well and really compare values on both sides of the river. Last option to "correct" the data (if you are dead sure about what you do), is to just lift the "wrong" regions to the correct height, using Matlab, masks etc.

Hi all,

I just did unwrapping once again, and height file looks much better now! Sorry for spamming! Thanks for ideas!

Sonya.