I used v.surf.rst but when i look at new (raster) and old (vector) values in a given point, they are not the same and even sometimes very remote from one another. I thought the interpolation would not modify values of points existing at the departure in the vector layer.
Should i try to fit the function parameters ?
Thanks
If you want the surface to pass exactly through the points (which can yield potential overshoots), set the smoothing to zero.
Mark
On Tue, May 20, 2008 at 1:12 PM, Stéphanie Faroux <stephanie.faroux@meteo.fr> wrote:
I used v.surf.rst but when i look at new (raster) and old (vector) values in a given point, they are not the same and even sometimes very remote from one another. I thought the interpolation would not modify values of points existing at the departure in the vector layer.
Should i try to fit the function parameters ?
Thanks
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I used v.surf.rst but when i look at new (raster) and old
(vector) values in a given point, they are not the same and even
sometimes very remote from one another.
I thought the interpolation would not modify values of points
existing at the departure in the vector layer.
v.surf.rst will not follow all the points exactly, it will try and create the best surface for all the data. (minimizing the overall energy to bend the surface) create and look at the deviations point map to see how far from each starting data point the surface is (then run v.univar on that).
see Helena's website for animations of what happens when varying the smoothing and tension parameters.
Hamish