[GRASS-user] Tessellation of a set of polygons

[Moritz Lennert]

On 29/08/13 17:38, Thomas Leduc wrote:
> Let's consider a set of input polygons (represented by dark gray
> polygonal footprints in the enclosed screenshot [1]). I wonder whether
> there already exists a (set of) GRASS instructions to produce the
> "surrounding tessellation". I mean, could you please tell me how to
> compute the set of multicolor polygons in the enclosed screenshot?
>
> As an example, the blue polygon is the set of points that are:
>    - overlayed by the dark gray polygon labeled #1
>    - or closer to the dark gray polygon labeled #1 than to any other
> input polygon.
>
> Thanks a lot for any help/advice.

You could try the following workflow:

- add category values to your boundaries (if that is important make them 
equal to the cat values of your centroids, otherwise just using 
v.category op=add type=boundary)
- use v.to.points to transform the boundaries to points (each point will 
have the cat value of the corresponding boundary)
- v.voronoi to create voronoir diagrams for these points
- v.dissolve to disolve boundaries between polyons with the same 
category numbers

Moritz