[GRASS-user] Strange r.slope.aspect output of Aster dem : slope calculations

[Markus Metz]

On Fri, Dec 20, 2013 at 4:54 PM, manuel.martin
<manuel.martin at orleans.inra.fr> wrote:
> Hi all,
> I just computed the slope using r.slope.aspect on the Aster data over the
> full French territory, and as a result got large artefact stripes on a south
> west-north east axe? When could it come from (inadequate re-projection, the
> slope routine or the aster data)?
>
> The stripped result :
> https://www.dropbox.com/s/fcxaei1be9wsmka/slopeFranceSmall.png
> https://www.dropbox.com/s/b52k5co46ujmpt7/slopeFrance.jpg

ASTER data are not really suitable to derive a DEM, your example is
another demonstration that an ASTER-derived DEM contains artefacts.
SRTM DEMs are without these artefacts.

Markus M