[GRASS-dev] How to create union of areas with isles

[Wolf Bergenheim]

On 09.08.2008 23:35, ????? ????? wrote:
> Hi,
> 
> I'm almost done with the new v.buffer module, but I need some help to finish it.
> I have the following problem. Suppose we have several line_pnts
> structs: A0, A1, A2, ...., An; B0, B1, B2, ..., Bm; ... (All lines are
> not self-intersecting) Here A0, B0, ... represent outer contours of
> areas and A1...An, B1, ... Bm, .... represent the corresponding isles
> (and no two isles A1...An intersect each other, and no isle of A1...An
> intersects A0. I.e. we have nice areas). How to create the map which
> consists of  the union of those areas A,B,... (Most of the times
> A,B,... will intersect each other)
> I have attached an example of such area - A with outer line A0, and
> isles A1, A2.
> 

Hmm the old v.buffer seems to work it so that it creates a line 
consisting of all points including the islands (note that island points 
are listed counter-clockwise). This will create bridges to the islands. 
Those are removed with a call to Vect_remove_bridges(); so I guess you 
don't need to worry about them.

Markus, Glynn, Hamish, is that right? Is there no way to create islands 
without creating bridges?

--Wolf

-- 

<:3 )---- Wolf Bergenheim ----( 8:>