On Thu, Jun 30, 2011 at 4:01 PM, Christian Guirreri <[email protected]> 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 > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
