[GRASS-user] v.generalize issues

[Christian Guirreri]

I'm on GRASS 6.4.1. QGIS 1.7.0

On Thu, Jun 30, 2011 at 10:18 AM, Markus Metz <
markus.metz.giswork at googlemail.com> wrote:

> On Thu, Jun 30, 2011 at 4:01 PM, Christian Guirreri
> <christian at guirreri.com> wrote:
> > I'm a brand new user to GIS - my goal right now is to heavily simplify
> Tiger
> > 2010 county and distrct data, without producing gaps between boundaries.
> > I've been testing this with v.generalize in grass via QuantumGIS - I've
> had
> > tons of issues with the Grass toolbox crashing, but have narrowed down to
> > using the Hermite algorithm. While it works, I'm having some bizarre
> issues
> > with it. Apologies for the cross-post with the PostGIS mailing list.
> >
> > In the attached gif of California counties, from left to right, I have
> used
> > the following tolerance values with the Hermite algorithm:
> >  - original
> >  - 1.0
> >  - 0.08
> >  - 0.01
> >  - 0.00001
> >
> > Why do counties disappear entirely as I decrease the tolerance?
> >
> This problem has been fixed in GRASS 6.4 only 2 weeks ago (June 13).
> Please update your GRASS version if possible.
>
> Markus M
>
>
> > In the Grass Tools I choose the v.generalize function. I choose Boundary
> as
> > the feature type (though I've tried checking others, as well as all of
> them
> > and it doesn't seem to change anything). Everything else is default,
> except
> > for tolerance as notated above.
> >
> > When I tested this originally on only Arkansas and Mississippi, I got
> really
> > nice results. I then tried it on the entire US and had the missing
> counties
> > problem. So I tried only California, and still have the same issue.
> >
> > I've tried other algorithms, but this has so far given me the detail I
> want
> > - of course sans counties! Any thoughts?
> >
> > Thanks,
> >  - Chris
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
> >
>
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