[GRASS-dev] Should v.in.ogr clean topology by default ? [was: Fwd: Re: [GRASS-user] overlapping areas seem valid to v.build: why?]

Moritz Lennert mlennert at club.worldonline.be
Thu Dec 1 05:02:28 EST 2011

I think Roger's question below merits reflection, so I forward it to the 
developer's list.


-------- Original Message --------
Subject: 	Re: [GRASS-user] overlapping areas seem valid to v.build: why?
Date: 	Wed, 30 Nov 2011 10:09:15 -0800
From: 	Roger André <randre at gmail.com>
To: 	Markus Metz <markus.metz.giswork at googlemail.com>
CC: 	Moritz Lennert <mlennert at club.worldonline.be>,
grass-user at lists.osgeo.org, "G. Allegri" <giohappy at gmail.com>

By the way, it seems that the official stance is that it is preferred to
allow the automatic cleaning of non-topological data sets when they are
imported.  However, I do want to point out that I have seen many, many
instances where this auto-cleaning actually causes problems, rather than
fixes them.  As a result, I explicitly exclude cleaning on every import
I do.  If cleaning is required, I manually clean the data with v.clean.
   In many cases only a subset of the full set of cleaning operations
performed automatically by v.in.ogr are needed to fix the data.
   Personally, I do not think this "auto cleaning" should ever have been
made the default operation of the import tool.

On Wed, Nov 30, 2011 at 9:37 AM, Markus Metz
<markus.metz.giswork at googlemail.com
<mailto:markus.metz.giswork at googlemail.com>> wrote:

     Moritz Lennert wrote:
      > On 30/11/11 14:38, Markus Metz wrote:
      >> It seems to me that the confusion arises because you made use of
      >> features that allow you to skip topological cleaning which is
     not the
      >> default and not recommended.
      > Maybe this calls for a v.check.topology module ? Or an option in
     v.build or
      > v.clean which does that (i.e. just check, not clean) ?

     Good idea. I would opt for a new option/flag for v.build, which can
     already provide rather detailed diagnostics, e.g. dumping topology.
     Something like v.build -e for extended topology checks?

     Markus M
     grass-user mailing list
     grass-user at lists.osgeo.org <mailto:grass-user at lists.osgeo.org>

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