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

[Maciej Sieczka]

Hamish wrote:
> Maciej Sieczka wrote:

>> BTW, not a question to Glynn really: I never understood the "Boundary
>> (1 area)" and "Boundary (2 areas)" explanations for color settings in
>> the Symbology tab. Eg., you can have one area, but it will be rendered
>> with color assigned to "Boundary (2 areas)" (light green, by default).
>> I suggest replacing "Boundary (1 area)" with "Boundary (broken area)"
>> and "Boundary (2 areas)" with "Boundary (valid area)". Anybody minds I
>> change this in CVS?
> 
> General plea to all devels: *If you don't understand something, please
> don't mess with it*.

That's why I asked a question instead of messing with it right away. I
was counting on some critics or insight, which you kindly gave.

> in the breakage screenshot there is a small green line showing "Boundary
> (between 2 valid areas)";

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.

 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 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?

BTW, this reminds me of this strange case:
http://kufaya.googlepages.com/vdigit_bnd.html. I swear that all the
vertices are snapped, including the last one. Yet, somehow, topology is
broken.

> note "the rest of the universe" acts as the 2nd good area for a closed
> polygon island.
> 
> if looking at the vector code consider areas to the left and right as
> you follow the boundary verticies CW or CCW around the centroid.
> 
> Of course you are right that "no,1,2" should be improved. But those have
> exact meanings which should not be blurred in the process.

I fully support this. Thanks for the feedback.

> ps- it is important to keep the order of feature rendering the same.
> that way bad nodes are drawn on top of good nodes and not hidden.

Sorry, I don't understand what you mean.

Maciek
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