[GRASS-user] Thiessen Polygons

[Jan Hartmann]

Glynn Clements wrote:
> Dylan Beaudette wrote:
>
>   
>>>> While we are on this topic, is there a way to get a weigthed voronoi
>>>> diagram using grass ?
>>>>
>>>> The ability to rank a point to tune the area's influence would be great,
>>>> for that purpose I've been using an arcgis'extension* but with grass it
>>>> is not possible**. Is there a way to get a similar result ?
>>>>
>>>> *http://www.geog.unt.edu/~pdong/software.htm
>>>> **http://osdir.com/ml/gis.grass.user/2004-04/msg00036.html
>>>>
>>>> Regards,
>>>> MORREALE Jean Roc
>>>>         
>> Now that I have read about 'weighted voronoi diagrams', I wonder if a
>> combination of r.cost + r.mapcalc would solve this problem. Something
>> along those lines is demonstrated here:
>>
>> http://casoilresource.lawr.ucdavis.edu/drupal/node/288
>>
>> This example isn't quite what is requested, although using r.cost with
>> start=point_i, and stop=neighbor_points (derived from v.delaunay /
>> v.distance?) may work. It would then be a little more work to convert
>> the weighted-distance rasters into polygons, and link back to the
>> original attribute tables... but (hopefully) not outside the realm of
>> possibility via a script.
>>     
>
> The problem with using r.cost is that you would need to know the cost
> for each cell before you have created the polygons.
>
> I think that the simplest accurate approach would be to modify
> r.grow.distance.
>
>   
Do you mean: adding a metric parameter to Euclidean, Squared, Manhattan, 
and Maximum? Something like: compute on the basis of the value of 
traversed cells?

Jan
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