[GRASS-user] r.surf.contour (again)

[Frank Broniewski]

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Hi,

I'd like to create a DEM from contours using r.surf.contours. Maybe I
am trying something to ambitious here because the region is quite
large and the relief is rather complex with lots of human made
modifications to the terrain. I used standard contours and contours
describing terrain features in combination with elevation points.

The region is:

nsres:      1
ewres:      1
rows:       12000
cols:       16000
cells:      192000000

and the calculation took amazing five days (or was it six days?).
Anyway, the result is unfortunately not what I would like to have
gotten. There links to three images with accompanying contour lines
[1][2][3] for some of the problems I encounter with the result, which
is btw. a hillshade computed from the DEM. To me it seems that the
contour lines are sometimes to dense and sometimes to far spaced for
the algorithm. And there are those straight line artefacts you can
find all over the place and some patterns that vaguely look like
quadtree pattern. And then there are those contour like black lines,
especially in [1] and [3] which I really can't explain.

Well I am willing to give it a second try and now I wonder what I can
do better. Increase resolution? Leave out some contour lines?

So any help is greatly appreciated :-)


Frank

PS
Grass is version 6.4.3 on Ubuntu 12.04



[1] http://www.geometrico.lu/devel/grass/hillshade1.jpeg
[2] http://www.geometrico.lu/devel/grass/hillshade2.jpeg
[3] http://www.geometrico.lu/devel/grass/hillshade3.jpeg

- -- 
Frank BRONIEWSKI

METRICO s.à r.l.
géomètres
technologies d'information géographique
rue des Romains 36
L-5433 NIEDERDONVEN

tél.: +352 26 74 94 - 28
fax.: +352 26 74 94 99
http://www.metrico.lu
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