[GRASS-user] Contours

Markus Neteler neteler at osgeo.org
Mon Dec 18 14:10:53 PST 2017


On Mon, Dec 18, 2017 at 6:38 PM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> On Mon, 18 Dec 2017, Shane Carey wrote:
>
>> I have a large DTM (5m cell size) and it covers an area of 100,000km2. I
>> need to create contours every 10meters in the dataset. If I tile the
>> dataset and contour each tile, the data, the contours act funny at the
>> edges, hence the need to process the area as one area. Is grass capable of
>> doing this?
>
>
> Shane,
>
>   Yes. As long as you have sufficient memory and drive space. You can always
> set the environment variable in ~/.bash_profile:
>
> export=GRASS_VECTOR_LOWMEM=1
>
> which will use available memory and not crash, while running more slowly.
>
>   If I'm wrong I'm sure we'll both read about it. :-)

Shane: please report how it goes.

Markus

PS:
If you want a tiled approach (could probably be partially run in
parallel), then you may create tiles with overlaps, then generate the
contour lines:
https://grass.osgeo.org/grass72/manuals/r.tile.html


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