[GRASSLIST:3304] Re: how to interpolate a raster?

leo.lami@katamail.com wrote:

> I'd like to smooth or interpolate a raster but I don't know how to do it.
> I tried with r.surf.idw but the result is not good for me.
> Are there other metods more flexible?

One alternative is to convert the raster to a sites file with
r.to.sites then use s.surf.rst.

--
Glynn Clements <glynn.clements@virgin.net>

Would you like to smooth an already done raster which is not very smooth without changing the resolution or with changing the resolution or would you like to interpolate a set of point (sites) data to get an estimation of the values between them?

In the first case you can use r.mfilter or r.mapcalc's neighborhood modifier. As far as I know r.mfilter does not handle floating point values.

In the second and third case just follow Glynn's suggestion. Or for a more in depth analysis you can use Gstat or R's geostatistic and spatial interpolation packages.

Miha

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On Thu, 29 Apr 2004, Miha STAUT wrote:

>leo.lami@katamail.com wrote:
>
> > I'd like to smooth or interpolate a raster but I don't know how to do
>it.
> > I tried with r.surf.idw but the result is not good for me.
> > Are there other metods more flexible?
>
>One alternative is to convert the raster to a sites file with
>r.to.sites then use s.surf.rst.
>
>--
>Glynn Clements <glynn.clements@virgin.net>

Would you like to smooth an already done raster which is not very smooth
without changing the resolution or with changing the resolution or would you
like to interpolate a set of point (sites) data to get an estimation of the
values between them?

In the first case you can use r.mfilter or r.mapcalc's neighborhood
modifier. As far as I know r.mfilter does not handle floating point values.

In the second and third case just follow Glynn's suggestion. Or for a more
in depth analysis you can use Gstat or R's geostatistic and spatial
interpolation packages.

Miha

_________________________________________________________________
MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*.
http://join.msn.com/?page=features/virus

r.neigbors worked for me (the tension was set too high on my DEM, creating
'waves' from the contour lines).

Dave