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

Laurent C. lrntct at gmail.com
Thu Sep 21 10:47:23 PDT 2017


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
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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