[GRASS-user] interpolation with data periodicity

Hamish hamish_nospam at yahoo.com
Tue May 15 03:00:13 EDT 2007

Schmitt Thierry wrote:
> I wonder if there is any way of interpolating data concidering a 360
> periodicity (namely current orientation). If there is no solution in
> GRASS, I would be interested in earing your suggestions (I might be
> able to code it).

(raster data)
split data from direction,magnitude into x and y (U,V) components,
interpolate those two maps, convert the result back to polar coords, and
visualize with d.rast.arrow.

See the d.rast.arrow help page for an example of the conversion.

If you only have direction and not magnitude data, use a unit magnitide
of "1" throughout.

(vector data)
use Matlab (or Octave). :)  [pol2cart() & cart2pol() fns]


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