[GRASSLIST:8067] v.surf.rst - serious errors in DEM
werchowyna at epf.pl
Thu Aug 25 15:55:25 EDT 2005
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.
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!
DEM resolution 1m, distance between the isoline and fault about 10-30
Such sudden ditches occur everywhere where faults contact the continous
surface. No matter how far is the closest isoline. Why is v.surf.rst
introducing such an error?
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