[GRASS-user] Thiessen Polygons

[Hamish]

Jan wrote:
> Wouldn't this work with cost surfaces too? Starting
> from several points (the Thiessen centers) with a grid cell
> cost information raster containing only the value
> "one", you get a raster representation of a
> classic Thiessen structure. Manipulating the cost
> information raster , you should get something like a
> weighted Thiessen structure. The last step would be to
> extract the boundaries between the polygons in vector
> format, with the methods above. Starting from each center
> point, the cost surface will rise, until it meets the rising
> surface from an adjacent point. At this location, slope
> becomes zero. These zero slope areas are effectively the
> Thiessen polygons, and can be vectorized. For normal
> Thiessen polygons, this should be no problem, but I am not
> sure what happens with really complex weighted cases. Does
> anyone have any experience with this?

right, the idea is to apply the wealth of landscape analysis modules
to the cost surface (or whatever) instead of a real DEM. Lots of power
there just waiting to be harnessed.


Hamish