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.<div><br></div><div>I'm going to try a fresh install of GRASS.</div>
<div><br></div><div><br><br><div class="gmail_quote">On Thu, Jun 30, 2011 at 10:52 AM, Daniel Lee <span dir="ltr"><<a href="mailto:lee@isi-solutions.org">lee@isi-solutions.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<p>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.</p>
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ISIS - International Solar Information Solutions</p>
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<div class="gmail_quote">Am 30.06.2011 16:02 schrieb "Christian Guirreri" <<a href="mailto:christian@guirreri.com" target="_blank">christian@guirreri.com</a>>:<div><div></div><div class="h5"><br type="attribution">
> I'm a brand new user to GIS - my goal right now is to heavily simplify Tiger<br>
> 2010 county and distrct data, without producing gaps between boundaries.<br>> I've been testing this with v.generalize in grass via QuantumGIS - I've had<br>> tons of issues with the Grass toolbox crashing, but have narrowed down to<br>
> using the Hermite algorithm. While it works, I'm having some bizarre issues<br>> with it. Apologies for the cross-post with the PostGIS mailing list.<br>> <br>> In the attached gif of California counties, from left to right, I have used<br>
> the following tolerance values with the Hermite algorithm:<br>> - original<br>> - 1.0<br>> - 0.08<br>> - 0.01<br>> - 0.00001<br>> <br>> Why do counties disappear entirely as I decrease the tolerance?<br>
> <br>> In the Grass Tools I choose the v.generalize function. I choose Boundary as<br>> the feature type (though I've tried checking others, as well as all of them<br>> and it doesn't seem to change anything). Everything else is default, except<br>
> for tolerance as notated above.<br>> <br>> When I tested this originally on only Arkansas and Mississippi, I got really<br>> nice results. I then tried it on the entire US and had the missing counties<br>> problem. So I tried only California, and still have the same issue.<br>
> <br>> I've tried other algorithms, but this has so far given me the detail I want<br>> - of course sans counties! Any thoughts?<br>> <br>> Thanks,<br>> - Chris<br></div></div></div>
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