[GRASS-user] No Data everywhere when I extract the shadow from a DEM using r.sunmask

[Helmut Kudrnovsky]

Hakim Benoudjit wrote
> Hello,
> 
> First of all, I'm new to this mailinglist and to GrassGIS in general.
> 
> So, I'm trying to use the `r.sunmask` command in order to extract the
> shadow from an `SRTM DEM` of the Alps mountains (Switzerland).
> The image had to be first `reprojected` when I've imported it to a
> `EPSG:21781` location, in order to get both the (lat, lon) in meters
> (similarly to the elevation).
> 
> Here is the command I'm executing (note that the time of the day was
> chosen
> at 09:00 in the morning to maximize the shadow):
> 
> r.sunmask elevation=n46_e006_1arc_v3 at PERMANENT output=alps-sunmask.tif
> year=2014 month=9 day=23 hour=9 minute=0 timezone=1
> 
> 
> The problem I have is that the image produced is emtpy (no-data
> everywhere).
> Is there a parameter I'm forgetting to add to the `r.sunmask` command?
> Or should I use `r.sun` command instead, even though I'm not sure about
> the
> parameters I should provide to it either ?
> 
> Hakim.

have you set your computional region to your DEM by g.region?



-----
best regards
Helmut
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