Understood. I actually started to try using some of the GRASS interface via QGIS, but on some of the panels, such as v.generalize, I couldn't type in a tolerance value. I'm on Win7 x64.
I'm going to try a fresh install of GRASS. On Thu, Jun 30, 2011 at 10:52 AM, Daniel Lee <[email protected]> wrote: > I've experienced problems with calling up vectors stored in the GRASS > database with QGIS, sometimes vectors simply are missing. Does the same > problem occur in the GRASS environment? Maybe it would help to try showing > the vectors in GRASS directly. If that work it means that QGIS is just > having a problem where it calls up the vectors from GRASS. My problem was > fixable by exporting the vectors as a shapefile and then loading them in > QGIS. > > -- > B.Sc. Daniel Lee > Geschäftsführung für Forschung und Entwicklung > ISIS - International Solar Information Solutions > > Deutschhausstr. 10 > 35037 Marburg > Festnetz: +49 6421 379 6256 > Mobil: +49 176 6127 7269 > E-Mail: [email protected] > Web: http://www.isi-solutions.org > Am 30.06.2011 16:02 schrieb "Christian Guirreri" <[email protected]>: > > > 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? > > > > 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 >
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