Bug in Create Stack - Stack of Coherence + Intensity

Dear Step Forum,

I am about to create a complex RGB composite following the tutorial from step user mfoumelis here:

On page 50-52 a data stack is created for the partly preprocessed Intensities and the coherence. I try to follow the exact workflow of all slides, but the “Create Stack” function does not work, since there is a complain saying:
S1 TOPS SLC products should use TOPS Coregistration.
So I tried the TOPS Coreg, which gave an error. Probably because products are already de-bursted and multi-looked.
Also the automatic coregistration fails, since it uses the create stack function as well.

Has there been any recent change?
I am convinced the coherence layer (maybe some old metadata entry) is responsible for the error, since the stack creation of the partly preprocessed intensities works.

Any alternative? Or may this be part of an update?

Thanks in advance

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Standard multi-looking destroys the phase so interferometry is no longer possible. You should always do co-registration and InSAR operations 1st and multilook only afterwards…

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Hi mengdahl,

I am afraid it is a bit more complicated then this. Maybe I haven’t explained well. My problem is not the creation of the coherence. I already have this layer, and of course, de-bursted and multi-looked just after. I also have successfully created the layers of the 2 VV polarized intensities of image t1/swath1 and t2/swath1 - following the processing steps explained in the link I posted above.

Now I want to create a stack in order to create a RGB composite which contains: R:Coh, G: VV_t1 + VV_t2, B: VV_t1-VV_t2. And that is where the problem lies. In order to do this RGB composite, I need to create a stack of those three layers. But as described in the above mentioned link, the Create Stack function gives an error as already explained in my first post. Please check the presentation of mfoumelis in case I am not expressing myself clearly.

My guess is that the metadata of the coherence is blocking the functionality of the Create Stack function, since it is recognized as a S1 SLC layer, which is actually not anymore the case.

Btw. I am using the latest SNAP version on Ubuntu 14.04.

Hope to get this solved. Thanks

I have exactly the same problem as AVollrath. I cannot create a stack with two IW SLC coregistered images + coherence, because the error “2.-CreateStack: S1 TOPS SLC products should use TOPS Coregistration” comes up in “Create Stack”. We would appreciate an explanation or solution :wink:

Hi there,

I experienced the same problem. I wanted to create an RGB image with a stack of two SLC sigma0 images and the coherence but the same error occured as mentioned above. And when I try to use the S1 TOPS SLC Coregistration with these images, there’s an error saying that the data must consist of multiple subswaths.

Hope someone can help us.

If the band sizes are the same in all products, you could use BandMerge operator in the GraphBuilder. Although you should also be able to create an RGB from different products as long as the location is the same and the band sizes are the same.

I’ll address the CreateStack problem for the next release.

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Great, that solves it. I could create successfully the RGB composite. Thanks!

I used the BandMerge operator to create a stack from other stackes (that are co-registered with the same master by backgeocoding) instead of CreateStack operator because it doesn’t handle TOPS data, the operator just put the bands together in one stack but you lose your metadata. and that generat double bands, you have the same bands with different names