[GRASS-dev] vector dissolve problems

Michael Barton michael.barton at asu.edu
Fri Nov 10 23:36:47 EST 2006

Let me know if you get any good tips. We have a similar  problem. One of my
students is trying to turn a series of soil maps in DXF format into soil
areas. The boundaries cut across soil areas. We've tried v.clean with snap
to no avail so far. She needs to close a LOT of polygons in order to turn
them to areas.

Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

> From: Markus Neteler <neteler at itc.it>
> Date: Fri, 10 Nov 2006 12:31:08 +0100
> To: GRASS developers list <grass-dev at grass.itc.it>
> Subject: [GRASS-dev] vector dissolve problems
> Hi,
> I try to merge the 100km tiles of the CORINE vector
> landcover maps which are delivered in SHAPE format.
> Due to the tiling there are annoying boundaries now
> when patching the tiles together. I then tried to
> reclass and dissolve them based on the landuse
> code to no avail.
> Procedure:
> for i in E43N26 E44N26 E45N26 E43N25 E44N25 E45N25
> do
>  unzip /cdrom/data/clc00/100km$i.zip
>  v.in.ogr 100km$i.shp out=clc2000_$i
> done
> v.patch -e `g.mlist type=vect pat="clc2000_*" sep=,` out=clc2000_tn_bl
> # break tile boundaries:
> v.clean clc2000_tn_bl out=clc2000_tn_bl_clean tool=break
> # reclass to landuse code:
> v.reclass clc2000_tn_bl_clean out=clc2000_tn_bl_recl col=CODE_00
> # dissolve 
> v.extract -d clc2000_tn_bl_recl out=clc2000_tn_bl_dissolved
> The resulting map remains essentially unchanged:
> http://mpa.itc.it/markus/tmp/vect_dissolve_troubles.png
> Manual removal in v.digit works. But since I have 700 tiles...
> Any ideas?
> Markus

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