<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">No! Please NEVER buffer with 0.<div><br></div><div>There are tons of tests on the web that proof that this recommendation of 1980ies GIS experts is destroying data.</div><div><br></div><div>There are modern feature, like „fix geometries“ in GEOS and others (pprepair).</div><div><br></div><div>We really need the web to forget about this recommendation.<br><br><div id="AppleMailSignature" dir="ltr">— <br><div>Von einem iPhone gesendet und wird daher Fehler enthalten.</div></div><div dir="ltr"><br>Am 29.10.2019 um 10:18 schrieb Marco <<a href="mailto:deduikertjes@xs4all.nl">deduikertjes@xs4all.nl</a>>:<br><br></div><blockquote type="cite"><div dir="ltr">
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Hi,<br>
<br>
Validity checks don't check the file format. They check the validity
of the geometries once they are read from the file into the
software.<br>
<br>
The shape file format is a partly documented format. It is very easy
to write a shape file which is not according to the specs. To my
experience ESRI software will do that every now and again. Very
probably you have one of those shape files.<br>
<br>
You might ask the person who created the files to:<br>
- buffer the geometries with a distance of 0 and the save the
resulting file again.<br>
- and/or export to a different file format (eg geopackage)<br>
<br>
Regards, MArco<br>
<br>
<div class="moz-cite-prefix">On 29-10-19 09:19, Casper Børgesen
wrote:<br>
</div>
<blockquote type="cite" cite="mid:32a3f0fc43bc41908e81ff0af0c7de28@sdfe.dk">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Hi
Pepa<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US">I have tried loading and exporting the
multipolygons as WKT using OGR/python and it looks like the
holes are interpreted as polygons.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US">FME displays the data (correctly?) with holes
and its validation engine doesn’t find any errors. BUT a
year ago I sent a bug report to SAFE because FME did some
automatic geometry repair when loading data => the
various programs could be fixing issues automatic which
means you won’t see them. Not to imply that ESRI does
automatic geometry repair in the background, but which
program can you definitely trust to correctly represent the
contents of your data set?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US">I tend to trust GDAL/OGR (which means I also
trust QGIS) because its open source and the developers are
normally pretty good at reporting back how the software
treats data.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US">My reply doesn’t fix your problem though, just
a few thoughts from me.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US">Regards, Casper<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" lang="EN-US">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" lang="EN-US"> gdal-dev
<a class="moz-txt-link-rfc2396E" href="mailto:gdal-dev-bounces@lists.osgeo.org"><gdal-dev-bounces@lists.osgeo.org></a>
<b>On Behalf Of </b>Pepa Beneš<br>
<b>Sent:</b> 29. oktober 2019 08:10<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><br>
<b>Subject:</b> [gdal-dev] Fwd: Gdal - multipolygon -
geometry errors instead holes<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<div>
<p class="MsoNormal">HI, <o:p></o:p></p>
</div>
<div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I recieved one shapefile. Gdal /
Grass / QGIS finds two geometry errors in it. Other
GIS SW (ArcMap, MapInfo (via Universal translator or
opening shp natively)) theay can't see this geometries
as errors. Instead errors they can see regular
multipolygons with holes there. Author of this shp
wants to see holes there too = in his opinion there
are correct data only. <br>
<br>
Please, write me, how to work with such geometries in
gdal / grass / QGIS / geos world to see holes too,
instead errors?<br>
<br>
In <a href="https://drive.google.com/file/d/1oRJQVKYDkZji-GLmobov995m9vF00vwf" moz-do-not-send="true">geometry_problem.zip</a>
there are:<br>
<br>
geometry_problem.qgz .. vizualization in QGIS<br>
<br>
original.shp .. original data prepared in ESRI<br>
original_esri.png .. original.shp seen in ArcMap (With
holes. Author of shp wants have holes there.)<br>
<br>
original_errors.shp .. geometry errors prepared by
"QGIS Desktop 3.8.3 with GRASS 7.6.1"<br>
original_qgis.png .. original.shp seen in QGIS<br>
<br>
MI/original_to_MI_by_UN.tab .. original.shp translated
from shp to tab by MapInfo - UniversalTranslator
(tried defferent versions with the same results).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Thanks <o:p></o:p></p>
</div>
<div>
<div>
<div>
<p class="MsoNormal">Pepa Beneš<o:p></o:p></p>
</div>
</div>
</div>
</div>
</div>
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<br>
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