Re: [GRASS-user] Re: XYZ Data (UTM32N) workflow to DEM and reprojection to Gauß Krüger 3

[Moritz Lennert]

On 14/05/12 15:28, Micha Silver wrote:
>   On 14/05/2012 15:52, Danny Luque Ramirez wrote:
>> Hi Moritz,
>>
>> thx for the quick answer :)
>>
>> What about the calculation of a DEM from XYZ data? I didn't find a tool to
>> perfom this within GRASS.

This depends a bit on the original form of you XYZ data: is it gridded, 
or just "randomly" located points ?

>
> v.surf.rst
> http://grass.osgeo.org/grass64/manuals/html64_user/v.surf.rst.html

Micha's solutions relies on importing your XYZ data as vector points, 
for example using v.in.ascii. The you can use any interpolation method, 
such as v.surf.rst, v.surf.idw, etc), to interpolate the data into a 
raster DEM.

r.in.xyz already does a form of interpolation as well, but not in such a 
sophisticated way: it takes XYZ ascii data and allows you to create a 
raster map with for each pixel a statistic based on the points that fall 
into that pixel. In your case the mean, the median or trimmed mean might 
be appropriate.

In both cases you have to carefully set your region (g.region) in order 
to get the raster you want in terms of pixel size and region extension.

Moritz