Digitizing in GRASS

[Justin Hickey]

Hello

I don't know if this will help you or not, but about a year ago I wrote a
module v.out.poly. If I remember correctly, this module's output is the same as
v.out.ascii except that it guarantees that each list of points is a complete
polygon instead of possibly being only an edge of a polygon, and the
coordinates are reversed.

I wrote this when we discovered that both GRASS and arc-info ouput area edges
and not complete polygons. We had a large polygon that was broken up into 3
edges but we needed to have a complete polygon as output. If the polygons are
broken up into edges, it is practically impossible to know which edges belong
to which polygon based on the output of v.out.ascii.

I never got around to submitting it to the source tree because it was a bit of
a hack to get our job done and I simply did not have a lot of time to clean it
up. Besides, I'm not a GIS person and I do not know if I did the proper thing
or not. I simply looked at GRASS function calls and data structures, found that
there was an area id and used it to output the points of the polygon. I copied
the v.out.ascii code and went from there. I don't even know if it is compatible
with version 5.

If you want to give it a try, I can send the code to you but I would strongly
recommend that you look through the code to see if it does what you expect.
It's not too long and is contained in a single file. I also put some comments
in to describe what the code does.

Again, I'm not sure if this will help you or not, but you are welcome to try it
if you want.

-- 
Sincerely,

Jazzman (a.k.a. Justin Hickey)  e-mail: jhickey at hpcc.nectec.or.th
High Performance Computing Center
National Electronics and Computer Technology Center (NECTEC)
Bangkok, Thailand
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People who think they know everything are very irritating to those
of us who do.  ---Anonymous

Jazz and Trek Rule!!!
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