[GRASS-user] Interpolating DEM from points with 'no data' area

Markus Neteler neteler at osgeo.org
Mon May 6 12:30:32 PDT 2013


On Mon, May 6, 2013 at 4:59 PM, Adrian Kirilov <kirilov.adrian at gmail.com> wrote:
>       Hello to the GRASS users,
>
>       I have a question about interpolating surface from vector points. I'm
> building surface for a large area 8x10km with IDW method, from point data
> derived from LiDAR.

IDW is not the best method for many cases. Please take a look here:

http://grasswiki.osgeo.org/wiki/Interpolation
(yes, that page could be still improved)

>       There is large area at the south-east side in the dataset (probably
> 1/3 of the whole set) with no data and also some small gaps in the data (in
> place of buildings). What to do when interpolating because the program
> interpolates also in the large 'no data' area resulting in flat surfaces and
> strange shapes there? How to proceed in this case?

You may try v.surf.bspline instead which uses B-splines rather than IDW.

Markus


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