[GRASS-user] Evaluation of AW3D30 open access global DEM for flood modelling

[Markus Metz]

On Thu, Sep 21, 2017 at 7:47 PM, Laurent C. <lrntct at gmail.com> wrote:
>
> 2017-09-20 4:07 GMT-05:00 Markus Metz <markus.metz.giswork at gmail.com>:
> >
> >
> > On Tue, Sep 19, 2017 at 9:10 PM, Markus Metz <
markus.metz.giswork at gmail.com>
> > wrote:
> >>
> >>
> >>
> >> On Tue, Sep 19, 2017 at 5:53 PM, Laurent C. <lrntct at gmail.com> wrote:
> >> >
> >> > Hello Markus,
> >> >
> >> > Thanks for your interest.
> >> > By SRTM1 we mean the 1 arcsecond version of SRTM. As far as we know,
it
> >> > comes in only one version.
> >>
> >> About USGS SRTM versions, see
> >> http://dx.doi.org/10.5067/MEaSUREs/SRTM/SRTMGL1.003
> >> https://dds.cr.usgs.gov/srtm/What_are_these.pdf
> >> https://dds.cr.usgs.gov/srtm/version2_1/Documentation/SRTM_Topo.pdf
> >>
> >> the latter one states that "there is a difference between the data
> >> distributed via ftp from the Land Processes
> >> Distributed Active Archive Center [now https://dds.cr.usgs.gov/srtm/],
and
> >> those available from the EROS Data Center"
> >>
> >> I am not sure if this still holds true. Following the EarthExplorer
links
> >> https://lta.cr.usgs.gov/SRTMVF
> >> https://lta.cr.usgs.gov/SRTM1Arc
> >>
> >> it is not clear which versions these are. I guess the non-void filled
> >> version of the EarthExplorer is the subsampled version 2.1, the void
filled
> >> version and the global 1 arc sec version are SRTM version 3. Just a
guess,
> >> if in doubt, ask USGS.
> >
> > According to
> >
https://lpdaac.usgs.gov/sites/default/files/public/measures/docs/NASA_SRTM_V3.pdf
> > and
> > https://lta.cr.usgs.gov/SRTM1Arc
> >
> > the USGS EarthExplorer most probably provides NGA version 2, not
JPL/NASA
> > versions 2.1 or 3.
>
> Markus,
>
> The JPL webpage about SRTM links to the USGS EROS website for
> download, which itself links to Earthexplorer:
> https://www2.jpl.nasa.gov/srtm/cbanddataproducts.html

The JPL/NASA website also links to
http://dds.cr.usgs.gov/srtm/
where you get the JPL/NASA SRTM products version 1 and 2.1

JPL/NASA SRTM version 3 (completely void-filled version 2.1) is available at
https://lpdaac.usgs.gov/dataset_discovery/measures/measures_products_table
JPL/NASA version 3 with 1 arc second resolution is described at
https://lpdaac.usgs.gov/dataset_discovery/measures/measures_products_table/srtmgl1_v003
JPL/NASA version 3 with 3 arc seconds resolution is described at
https://lpdaac.usgs.gov/dataset_discovery/measures/measures_products_table/srtmgl3_v003

Personally, I would prefer SRTM JPL/NASA version 3 over any other SRTM
version, mainly because according to the documentation it supersedes the
NGA version 2 available through the USGS EartExplorer.

Markus M

> https://eros.usgs.gov/elevation-products
>
> Do you know if there is a more recent version of the 1 arcsec product,
> and where to find it?
>
> Best,
> Laurent
>
> >
> > Markus M
> >>
> >> > We could make it more clear during the revision.
> >>
> >> That would avoid confusion. For example, there is a 1 arc second
version
> >> of version 2.1 ;-)
> >>
> >> Markus M
> >>
> >> >
> >> > Best,
> >> > Laurent
> >> >
> >> > On 19 Sep 2017 01:49, "Markus Metz" <markus.metz.giswork at gmail.com>
> >> > wrote:
> >> >
> >> >
> >> >
> >> > On Tue, Sep 19, 2017 at 1:41 AM, Laurent C. <lrntct at gmail.com> wrote:
> >> > >
> >> > > Hello all,
> >> > >
> >> > > Open-access global DEMs like SRTM are a staple in our GIS
community.
> >> > > Last year the JAXA released a new product, the ALOS World 3d 30m
> >> > > (AW3D30).
> >> > > Using GRASS and itzï we've carried out an assessment of AW3D30 from
> >> > > the point of view of flood modelling, and compared it to lidar,
SRTM
> >> > > and ASTER.
> >> >
> >> > Very interesting study! I have a question about SRTM: in the paper
you
> >> > write that you used SRTM version 1, but SRTM version 1 is
practically not
> >> > used since version 2.1 has been made available. Since 2013, SRTM
version 3
> >> > has been available:
> >> >
> >> > http://dx.doi.org/10.5067/MEaSUREs/SRTM/SRTMGL1.003
> >> >
> >> > SRTM version 3 is also the default for r.in.srtm.region.
> >> >
> >> > Best,
> >> >
> >> > Markus M
> >> >
> >> > >
> >> > > AW3D30 is indeed a very interesting product, and I thought that
GRASS
> >> > > users could be interested in our results:
> >> > > https://doi.org/10.5281/zenodo.885571
> >> > >
> >> > > Best regards,
> >> > > Laurent
> >> > > _______________________________________________
> >> > > grass-user mailing list
> >> > > grass-user at lists.osgeo.org
> >> > > https://lists.osgeo.org/mailman/listinfo/grass-user
> >> >
> >> >
> >
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