Digitizing in GRASS

[Alejandro Imass]

David D Gray wrote:

>
>
> so-called `arc-node' format, unless it is a simple island, of
> course, but there is none in this topology. If v.out.ascii or
> v.out.arc is producing actual closed rings there must be
> something wrong with the original map.

Thanks David. This is correct and I verified this, it is indeed producing a
correct arc-node format.
(I suppose then that area labeling creates the centroids?)
I have the same problem as Justin Hickey describes, but I don't know how to deal
w/ it. I too was hacking my way last night at the ascii files, but there should
be an explanation, and it's probably a simple one.

I noticed that gen2shp does not use the lab file (I really don't know if it
supposed to), so I guess that the centroids are ignored. This is perhaps the
reason that the shape viewer I'm using interprets 6 polygons instead of 3 and
closes each arc separately by throwing a straight line between the nodes.

So now some more questions come to mind:

1) Is there a utility such as Justin Hickey's hack that figures out a closed
polygon taking the centroids from the area labels and generating the appropriate
ascii file?
2) Is there really a problem w/ gen2shp and it should take the lab file into
account (or perhaps the problem is mine and I did not understand the source
code) ? Maybe gen2shp was designed with (1) in mind ?!
3) I noticed a centroid calculator in the contrib dir of shapelib. Maybe gen2shp
expects shapelib to figure this out?
4) Is there a problem with the shape file viewer I'm using (MapServer) and IT
should figure out what the polygons should like? (But without a centroid I
consider this a tough job, unless it would use something like mentioned in (3)!)
5) Am I completely off course here ?

If (2) is true I would be more than happy to throw in my 2 cents and modify
gen2shp "...with a little help from my friends..." of course!
As I said before I'm so happy w/ GRASS that I would really like to contribute to
this project, in any way that I can.

Thanks to all.

Alejandro Imass