[GRASS5] v.buffer now does v.bubble

[Radim Blazek]

> On the positive side only the new code is broken and using a
> constant buffer will still work the same, so we don't have to revert
> the code while we try for a fix. And I think it is useful even now.

It can be for a while in CVS, but it cannot be in release.

> I am forgetting the module that adds missing centroids.. maybe document
> v.extract type=boundary + that as a work around until it is fixed.
> Or is there a problem whether or not islands/holes get a category number
> when they shouldn't then?

Yes it is problem, it works like this:
1) generate boundaries around input features
2) break and clean boundaries to get clean topology
3) create centroids in ALL areas (including those outside
    buffer, e.g. those which become islands in utput)
4) identify centroids in buffer
5) merge (dissolve boundaries) areas in buffer
6) delete centroids outside buffer

> For a v.bubble replacement it isn't very good to use this module as
> small bubbles will be disolved in bigger bubbles.

I will be once we add also the possibility to assign categories
of input features to buffers. That means merge only the areas
with the same categories. So I think you can go on here.

Radim