Get coordinates of an SLC subswath for Sentinel 1

Hello

I’m looking for a way to get approximate coordinates for one sub-swath of an Sentinel-1 SLC image (IW3 for example). I looked at manifest.safe in my data folder but there is only the global coordinates of the image.

For now, the only solution that I have is to get global coordinates of the image, divide the rectangle into 3 vertical rectangle and I got one rectangle for each sub-swath.
I wonder if there are more precise solution.

Does anyone have an hint for me? Thanks you

Open the S-1 SLC product in SNAP, go to Metadata => Original_Product_Metadata => annotation, you will see the metadata of all sub-swathes. Inside the sub-swath metadata, you will see Product => geolocationGrid which is probably what you are looking for

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If I’m not mistaken the geolocation grid is based on ellipsoid geocoded coordinates so it is incorrect over areas that are not at sea-level. For some applications this does not matter but one should be aware of it.

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Thanks! That was the information that I needed.

@mengdahl It shouldn’t be a problem for my range of accuracy but it’s good to know.
However, the geolocation grid points have a height attribute that is different from 0 and quasi constant over one line of the grid so it’s a bit curious.

For future reference for anyone else interested in using the GeolocationGrid:

This European Commission report: dx.doi.org/10.2788/132810 on pages 21 and 46 has information about the GeolocationGrid and why it isn’t good for direct use if you need high accuracy.

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