From grass-lists-owner@max.cecer.army.mil Tue Aug 3 15:08:01 1993
Date: Tue, 3 Aug 93 16:50:49 CDT
From: mg@adasn4.agr.okstate.edu (Mark S. Gregory)
Sender: grass-lists-owner@max.cecer.army.mil
Reply-To: grassu-list@max.cecer.army.mil
To: grassu-list@max.cecer.army.mil
Subject: Importing polygons
Content-Length: 807I have received some data in which all of the areas are defined as polygons.
Even those areas which have common edges with other areas are contained as
complete polygons.I can import the polygons into GRASS without any trouble. I would, however,
like to convert the polygons to 'area edges' or segments in the manner that
GRASS stores areas. Manually 'breaking the lines' in v.digit, then 'snapping'
the nodes, and removing the multiple lines (the common borders) is a tedious,
imprecise and often very complicated operation. Am I missing something in
GRASS that would make this easier?Any thoughts on the subject would be greatly appreciated.
Mark Gregory mg@adasn4.agr.okstate.edu
Oklahoma State University (405)744-6417
Stillwater, OK 74078 (405)744-5269 fax
Would
v.spag -i threshold=0
take care of this??? In theory it would create nodes at each of
the overlapping polygon intersections, and then cut out the duplicate
area edges. I have had good luck in general with v.spag -i, however,
I generally have to do a little cleaning to correct for "almost"
identical lines etc. Give it a shot (on a copy of course) and
good luck.
Sue Huse
REGIS
UC Berkeley.