[gdal-dev] Potential issue with Sentinel-1 SAFE driver

Alessandro Amici a.amici at bopen.eu
Fri May 13 11:53:52 PDT 2016


Even,

furthermore subswaths typically have different pixel and line sizes.

But the subswath level is easy bit of Sentinel-1 data, the real fun starts
as you note that every individual tiff file is a collection of actual image
segments (the bursts) interleaved with black stripes. The image segments
actually overlaps by a small amount. As far as I can tell the current
driver doesn't make any effort to recompose the swath image.

As a matter of fact I'm not even sure what strategy can be used to make the
Sentinel-1 data fit into the normal GDAL data model. Maybe treating bursts
as image tiles?

Cheers,
Alessandro


On Fri, 13 May 2016 at 15:54 Even Rouault <even.rouault at spatialys.com>
wrote:

>
> > This is obviously wrong, since pixels in each swath correspond to
> > different observed ground points. In other word, there is no meaning in
> > stacking the response of pixel (0,0) of swath one with pixel (0,0) of
> > swath two, since they do not observe the same target landscape.
> >
> > I think the best would be to report at least the different swath as
> > subdatasets (as done in S2 driver). For the sake of simplicity,
> > polarisations too could be exposed as subdatasets.
>
> Julien,
>
> Looking quickly at the driver and with the observations you made, your
> suggestions make sense to me. The swaths should defintely be in separate
> subdatasets, and the GCP fetched from the appropriate annotation file.
> Whether
> polarisations of the same swath are in different subdatasets is a matter of
> taste (looking quickly in the code base I see the CPG driver also puts the
> polarizations as different bands of the same dataset). Perhaps Delfim has
> some
> comments?
>
> Even
>
> --
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-- 
Alessandro Amici <a.amici at bopen.eu>
CTO at B-Open Solutions - http://www.bopen.eu/
Viale Palmiro Togliatti, 1639 - 00155 Roma - tel: +39 06 8370 8269
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