[GRASS-user] DEM with bathymetric contour lines

[Tomáš Brunclík]

Hello Irantzu,
As I said, for anyone to be able to help, please post the exact commands 
used (all from the beginning, not just the last one which fails) and 
GRASS version and operating system, just like Markus did in his post. If 
you are using GUI tools, there is the copy button in the command 
dialogs, that will allow you to paste the command parameters to e-mail. 
Also, address the reply back to the conference - more people may have ideas.
It occurs to me, that if there is no error, and the interpolation throws 
unchanged input raster on you, that perhaps the input raster contains 
zero values instead of no-data (null) values or something - then there 
would be nothing to interpolate... But without seeing the data or the 
commands used it is just wild guessing..
Regards,
Tomas

Dne 25.5.2015 v 13:43 Irantzu Alvarez napsal(a):
> Hello Tomas,
> As you said, I think that the problem could be in the volume of data. 
> My contours are of 300 MB and if I set a region with resolution of 1 m 
> (the one I would like to perform) the output raster has over 3 billion 
> cells. Although I have a high capacity computer, grass doen't compute 
> the surface.  With a resolution of 10 m my region setting are:
> g.region -p
> projection: 1 (UTM)
> zone:       30
> datum:      etrs89
> ellipsoid:  grs80
> north:      4818930
> south:      4791480
> west:       486510
> east:       601280
> nsres:      10
> ewres:      10
> rows:       2745
> cols:       11477
> cells:      31504365
>
> I am trying to generalize contours, in order to reduce the contour 
> file, but I don't know which algorithm is better in that case.
> After that I will try to use diferrent resolutions to see if that is 
> the problem.
>
> All the best,
> irantzu
>
>
>
>
> 2015-05-25 10:12 GMT+02:00 Tomáš Brunclík <brunclik at atlas.cz 
> <mailto:brunclik at atlas.cz>>:
>
>     Hello,
>     I tried to process bathymetry lines with negative elevation and it
>     just worked in GRASS 7.0.1svn r65198 @Linux. Maybe try if it works
>     with coarser resolution or region subset to test if the data
>     volume is the problem, or if your version of GRASS really has
>     problem with negative elevation values. Also try to look if the
>     input raster contains expected values, if you did not check that
>     already.
>     If the problem persists, post your findings with log of the
>     commands you used, your GRASS version and platform.
>     If it seems a problem of the GRASS module, and you are using a
>     recent version of GRASS, it would be better to fill a bug,
>     instructions at http://grass.osgeo.org/development/bug-tracking/
>     Regards,
>     Tomas Brunclik
>
>     Dne 18.5.2015 v 16:47 Irantzu Alvarez napsal(a):
>>
>>     I am trying to create a DEM from a bathymetric contour lines.
>>     Contours are in vector format and the elevation value is negative
>>     (integers). To create the surface I have converted the contours
>>     in raster (v.to <http://v.to> rast) and then I have used
>>     r.surf.contour, but It doesn't work (there is no error but the
>>     resulting output rasteris exactly the same as the previous one,
>>     without any interpolation).
>>
>>     This are my region settings:
>>
>>     g.region -p -a raster=contours at iiaa nsres=1 ewres=1
>>
>>     projection: 1 (UTM)
>>
>>     zone:30
>>
>>     datum:etrs89
>>
>>     ellipsoid:grs80
>>
>>     north:4818927
>>
>>     south:4791484
>>
>>     west:486512
>>
>>     east:601275
>>
>>     nsres:1
>>
>>     ewres:1
>>
>>     rows:27443
>>
>>     cols:114763
>>
>>     cells:3149441009 <tel:3149441009>
>>
>>
>>
>>     I need a DEM of very high resolution of a wide area. I am using a
>>     computer with large capacities for it.
>>
>>
>>     Could someone help me please?
>>
>>
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>
>
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