[GRASS-dev] r.fill.gaps porting

Vaclav Petras wenzeslaus at gmail.com
Sat Apr 15 18:40:50 PDT 2017


On Sat, Apr 15, 2017 at 8:32 AM, Benjamin Ducke <benducke at fastmail.fm>
wrote:

> The thing is: I originally developed this module for
> gradiometer data. That data is very noisy and has
> high local variation. Interpolating that type of
> data while preserving original measurements will
> usually result in unsatisfactory output. Also note
> that the smoothing increases with the interpolation
> radius. For tiny holes in LiDAR data, try "distance=1"
> or "2". Of course, LiDAR data probably has different
> properties and does not need low-pass filtering
> like gradiometer data. So try "-p" to preserve the
> original values.
>
> An alternative would be to invert the behaviour of
> the module and assume "-p" by default.
>
> I don't work with LiDAR data myself, but I would very
> interested to know your results!
>


I've added a figure which shows the r.slope.aspect products from the
surface without and with -p. You can see that the smoothing gives
significantly different results and probably better ones. I had the same
experience in past when trying to patch result of r.neighbors with the
original raster. Perhaps using smaller distance as you say or greater power
would help, but I haven't tested that yet.

I managed to commit just the figure its caption. If somebody gets to it,
please extent the section.
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