[GRASS-dev] vector dissolve problems

[Markus Neteler]

It tends to drive me crazy...
So: Attached box.asc for Spearfish as test case.

# Import:
 v.in.ascii box.asc out=box format=standard
 g.region vect=box
 d.mon x0
 d.vect box
 d.vect box disp=cat

# Here maybe the first problem starts: Do we need also
# the boundaries to be of the cat of the centroid?
# Anyway, can be easily changed in box.asc.

# dissolve:
 v.extract -d box out=box_diss
 d.vect box_diss

# nothing dissolved :-(

Questions:
- is the test case correct (I suspect not)?
- with a working test case, does it work with 6.2 and 6.3 or
  only 6.2 (I suspect 6.2 only)

I used it in September to dissolve VMAP0 gridlines, so
it worked...

Let's fix this test case and include it into v.extract for
Soeren's test suite.

Markus

On Fri, Nov 10, 2006 at 09:36:47PM -0700, Michael Barton wrote:
> 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
> __________________________________________
> 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
> > 
> > 
> 

-- 
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
-------------- next part --------------
ORGANIZATION: 
DIGIT DATE:   
DIGIT NAME:   neteler
MAP NAME:     
MAP DATE:     Sat Nov 11 16:08:03 2006
MAP SCALE:    1
OTHER INFO:   
ZONE:         0
MAP THRESH:   0.000000
VERTI:
B  2 1
 599252.27604468 4919906.2533062
 594243.1875  4920467.4375
 1     1         
B  3 1
 594243.1875  4920467.4375
 596091.5625  4926757.875 
 599807.47153304 4925254.99623553
 1     1         
B  4 1
 599807.47153304 4925254.99623553
 602799.375   4924044.9375
 601428       4919662.5   
 599252.27604468 4919906.2533062
 1     1         
B  2 1
 599252.27604468 4919906.2533062
 599807.47153304 4925254.99623553
 1     2         
C  1 1
 597552.375   4923120.75  
 1     3         
C  1 1
 600831.75    4922733.1875
 1     3