[GRASS-user] Topo to Raster

Martin Landa landa.martin at gmail.com
Tue Apr 1 03:37:21 PDT 2014


2014-03-04 19:25 GMT+01:00 Mark Seibel <mseibel at gmail.com>:

> Are there specific inputs of the "topo to raster" tool that are of
> importance for your application?

not really I just want to show my students that almost everything what
they are doing in the class using ArcGIS they can do using open source
GRASS GIS quite easily  :-)

> Using contour lines as input, I have found the r.surf.nnbathy module to
> perform very well.  For (LiDAR) point data, my preference is v.surf.rst.

Right, `r.surf.nnbathy` is based on Pavel Sakov's nn natural neighbor
interpolation library. This library is provided in MIT licence. Then
we could probably incorporate it into main GRASS source code, right? I
found code in Addons [1], btw, link at [2] doesn't work. The module is
written as a bash script and needs to be ported to Python for G7.

What do you think?

> If one wanted to mimic the arcgis method of filling sinks after
> interpolating, one could run iterations of r.fill.dir to make it
> depression-less.  This isnt necessary with the hydrologic tools in GRASS
> because the r.watershed algorithm is intelligent enough to keep seeking the
> next lowest location the DEM.  Add in the fact that r.watershed has MFD, and
> GRASS quickly surpasses the ESRI hydrologic toolset offerings.

Thanks for clarification.


[1] http://trac.osgeo.org/grass/browser/grass-addons/grass6/raster/r.surf.nnbathy/r.surf.nnbathy
[2] http://grasswiki.osgeo.org/wiki/AddOns/GRASS_6#r.surf.nnbathy

Martin Landa * http://geo.fsv.cvut.cz/gwiki/Landa

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