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

[Dylan Beaudette]

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!
>
[snip]

Maciek,

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?

best,


-- 
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341