Another option is to use GMT grdcontour program
gmt grdcontour 6800_2480.tif -C1 -Dlixo.dat -V
it creates a ~8.3 Mb ascii file with a memory consuption of ~50 Mb (Task
manager info) that you can later convert to shp with ogr2ogr
Stefan,
I have problems creating contours with gdal_contour and some tiff files.
The following command
gdal_contour -i 1.0 6800_2480.tif out.shp
ends with "0Killed" after eating all memory and all swap. It happens
with
gdal 1.11 and gdal-master. It did work on a Ubuntu 10.04 machine (as
far as
I remember). Now I'm on Ubuntu 14.04.
Comparing the source code, the algorithm hasn't fundamentaly changed, at
least
since GDAL 1.5. I can reproduce your issue with latest trunk or 1.5.X.
It is related to the fact that your source dataset has floating point
values.
An easy workaround is to translate your raster into a Int16 one and
contour
it. I've just tried it and it works.
Or you could possibly round values to 0.5 precision with gdal_calc.py for
perhaps a smoother result. But basically the contour alg seems to
require a
lot of memory if every pixel is different from its neighbour (might be an
approximation of what happens as the algorithm is non trivial and I
didn't
study it in detail).
It might be worth opening a ticket on that.
Even
Tiff file can be found here:
http://maps.zh.ch/download/hoehen/2014/dtm/tif/6800_2480.tif
Any ideas?
regards
Stefan
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