[GRASSLIST:8068] Re: v.surf.rst - serious errors in DEM

Dylan Beaudette dylan at iici.no-ip.org
Thu Aug 25 17:19:28 EDT 2005

On Thursday 25 August 2005 12:55 pm, Maciek Sieczka wrote:
> Helena, All,
> I have run v.surf.rst on a dataset which consists of sparse elevation
> contour lines and single elevation points (for hill tops) and several spots
> of very dense elevation points, indicating elevation faults.
> On
> http://www.biol.uni.wroc.pl/sieczka/udostepnione/vsurfrst.png (160 KB)
> and it's 10x exagaration
> http://www.biol.uni.wroc.pl/sieczka/udostepnione/vsurfrst_exag.png (237 KB)
> you can see that there is a strange artifact in the interpolated DEM. I
> mean these series of pits between the isoline on the right and the
> elevation points indicating faults to it's left. How come? The elevation of
> the isoline is slightly (decimeters) more than the elevation of the highest
> points in the fault, so I expected a smooth elevation gradient from the
> isoline towards the fault - but there is a ditch instead!


I am by no means an expert on this, but it looks like your tension parameter 
is set too high... what were the parameters for the interpolation?


Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis

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