[GRASS-dev] boundaries, areas and between [was: v.digit replacement [was: Modules]]

[Moritz Lennert]

On Tue, February 27, 2007 23:20, Maciej Sieczka wrote:
>
> If there is only one, valid, area, it still is green, but describing it
> as "Boundary (between 2 valid areas)" or "Boundary (2 areas)" does not
> make sense.

Unless you take into account that the rest of the universe is counted as a
valid area.

>
>  and orange "Boundary (between 1 complete
>> area and one not good area)"; and grey "Boundary (which doesn't form an
>> area)".
>
> Proposition:
>
> was:                 to be:
>
> Boundary (no area)   Boundary not closed
> Boundary (1 area)    Boundary closed, invalid
> Boundary (2 areas)   Boundary closed, valid

I don't think that the boundary which has only one area next to it is
invalid.


> I have one more problem. Can you look at my drawings. Shouldn't the
> east-most area be either all-good-green (vdig_badarea_ms.png) or
> all-bad-orange (vdig_badarea_ms2.png), and not a mix of the two, as it is?

The way I understand this is that the rest of the universe is considered
as a valid area, unless it is in "touch" with an unclosed boundary. At
that moment the rest of the universe is not "rest of the universe" anymore
but the potential content of this unclosed boundary. So, the boundaries
are orange because what should be the rest of the universe, and thus a
valid area, cannot be considered as such. If you close the western area,
then the rest of the universe becomes a valid area and each boundary thus
delimites two areas.
The one boundary which is green is the only one between two areas.

I hope I make any sense ;-)