BandMath operation between SAR image and any geotiff

Hi everyone,

I hope my topic hasn’t already been discussed, but I cannot find a solution to my problem.

In my work I produced an interferogram, which is still in SAR coordinates. However, my interferogram in corrupted by some atmospheric disturbances.

To correct it, I asked my climatology department to produce a geotiff of a variable. My job is then to correct my interferogram by a very simplistic relation like :

ifg_corrected = ifg - A * MyGeoTiff

And I would like to do it in radar coordinates.

Is there any solution in SNAP to do it?

Thanks in advance,


I found a solution but that’s a bit annoying.

If you want to use a geotiff in your radar geometries, the module collocation is for you. There, you can select your radar image as a master and your geotiff as a slave, in order not to modify the radar image. Doing that, you now have a new Beam-Dimap container with all your images. Great.

However, if you have 6 geotiff to collocate, you have to use 6 times the collocation tool (creating in the way a huge amount of data). That’s a bit boring.

As a remark, it would be great simply to let people choose how many slave images they want to add in the collocation process, using the same interface that in stack tool for example. Thanks :slight_smile:

Hello Quentin, there is currently no option in SNAP to do radarcoding into slant-range coordinates. It is in the plans but not in the near future.

Hello @mengdahl. But what I’m doing is still a radarcoding in some sense, right?

It’s good to hear that it is in the plans. These are the kind of lacking features that allow my colleagues to tell me “why don’t you use GAMMA?”

Well, collocation does not correct for radar-specific distortions caused by the terrain so I would guess it can only sort-of-work on almost flat areas.

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My area have 20m elevation difference on almost 30 000 meter distance so I guess I can consider it as “almost flat” :wink: