[GRASS-dev] vector dissolve problems

[Markus Neteler]

Dylan,

no, it actually used to work! Something is broken now
with the dissolving. Probably only in 6.3 due to
cats management changes?

Markus

On Fri, Nov 10, 2006 at 08:50:25AM -0800, Dylan Beaudette wrote:
> Hi Markus,
> 
> This is a feature that would be very helpful to have in GRASS. Until
> my adventures with PostGIS, I would have to resort to using Arc-*** to
> perform this sort of "dissolve". While this functionality is simple to
> use in PostGIS, dissolve operations on VERY large datasets can be time
> consuming.
> 
> Here is a relevant thread on the topic:
> http://www.archivesat.com/PostGIS_Users_Discussion/thread690148.htm
> 
> Cheers,
> 
> Dylan
> 
> On 11/10/06, Markus Neteler <neteler at itc.it> wrote:
> >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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> >
> 
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-- 
Markus Neteler  <neteler itc it>  http://mpa.itc.it/markus/
ITC-irst -  Centro per la Ricerca Scientifica e Tecnologica
MPBA - Predictive Models for Biol. & Environ. Data Analysis
Via Sommarive, 18        -       38050 Povo (Trento), Italy