[GRASS-user] creating high-resolution DMT

Vaclav Petras wenzeslaus at gmail.com
Fri Apr 14 20:31:02 PDT 2017

Back to filling holes in lidar data, I also think that the "fill in the
gaps" approach is quite promising, so I ported the r.fill.gaps module to G7:


I didn't review the code, but the documentation is very nice and detailed.
I did some mostly formatting updates for the current submitting guidelines
and added complete example with lidar data.

On Tue, Mar 21, 2017 at 7:29 AM, Benjamin Ducke <benducke at fastmail.fm>

> I just realized that I have never committed "r.fill.gaps"
> to the add-ins repo.
Really nice module, please, find more of these in your shelf :-)


> I have just done that now:
> http://grasswiki.osgeo.org/wiki/AddOns/GRASS_6#r.fill.gaps
> Its purpose is filling small gaps in otherwise dense
> data using IDW with a pre-computed weights matrix.
> It works on rasterized data, so you simply use v.to.rast
> on your vector points first. Make sure to set the
> cell size small enough so that you don't get many
> vector points falling into the same cell. The result
> will be an oversampled raster with a lot of small
> "no data" cells. That's exactly the intended input for
> r.fill.gaps!
> This is not multi-core code, (parallelizing
> interpolation algorithms is hard, because you need to
> segment the data and then you need to deal with the
> seams between the segments), but it is very, very fast,
> as long as you keep the IDW radius small.
> The code is optimized to death, which makes it very
> hard to read. Another drawback is that it was written
> for GRASS 6 (but converting it to GRASS 7 should not
> be hard, since it uses only the basic raster API).
> r.fill.gaps is not useful for filling large gaps, both
> in terms of performance (for large IDW radii) and
> interpolation quality (it's IDW -- enough said).
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