Thanks for filing the bug. It's definitely something bad, I did a test where I buffered every country in the world and then underlaid the original shapefile in solid red. There are alot of random places showing though. The explode, buffer, union and re-assemble process seems to give correct results though.<br>
<br>Thanks again for the follow-up.<br>--<br><br><div class="gmail_quote">On Thu, Mar 26, 2009 at 11:02 AM, Martin Davis <span dir="ltr"><<a href="mailto:mbdavis@refractions.net">mbdavis@refractions.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Thanks for that. Nice test case! FWIW, this runs fine in JTS. Hopefully someone on the GEOS side can take a look at this.<br>
<br>
Roger André wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div class="im">
Ok, here is the WKB. Let me know if there are any problems with the file.<br>
--<br>
<br></div><div><div></div><div class="h5">
On Thu, Mar 26, 2009 at 8:57 AM, Martin Davis <<a href="mailto:mbdavis@refractions.net" target="_blank">mbdavis@refractions.net</a> <mailto:<a href="mailto:mbdavis@refractions.net" target="_blank">mbdavis@refractions.net</a>>> wrote:<br>
<br>
I don't think this can be the problem - a buffer of a linestring<br>
should still produce a polygon.<br>
<br>
This is probably a bug in the GEOS buffer algorithm. It would<br>
help if you posted the WKB or WKB for the geometry.<br>
<br>
<br>
Chris Hermansen wrote:<br>
<br>
This sounds to me like you might be buffering a linestring and<br>
not a<br>
polygon. Is that possible? Ie are the countries represented as<br>
outlines (linestrings) rather than polygons?<br>
<br>
Roger André wrote:<br>
<br>
Hi All,<br>
<br>
I'm having some problems with features that are being<br>
returned from an<br>
ST_Buffer operation in PostGIS. When I try to buffer the<br>
extents of<br>
Papua New Guinea, a large region in the middle of its<br>
extents is<br>
omitted. You can see a visual representation of this at<br>
<a href="http://lagerratrobe.blogspot.com/2009/03/problem-with-postgis-stbuffer.html" target="_blank">http://lagerratrobe.blogspot.com/2009/03/problem-with-postgis-stbuffer.html</a><br>
<br>
If I just select the country itself, I get back all of the<br>
features<br>
that I'm expecting. In the image I've posted above, the<br>
black area<br>
indicates the results of that query.<br>
<br>
I am using postgresql-8.3.5, and postgis-1.3.3. My select<br>
statements<br>
is as follows:<br>
select name, Buffer(the_geom, .12) from coastlines where<br>
iso_3_code = 'PNG';<br>
<br>
I've tried this using both a free countries shapefile, as<br>
well as an<br>
ESRI one, and get the same results. I'm a bit baffled,<br>
and unsure if<br>
I have a problem with both data sets, or in my query,<br>
or...? If<br>
someone else has had a similar problem in the past, and<br>
can shed some<br>
light on it, I'd greatly appreciate it.<br>
<br>
Thanks in advance,<br>
<br>
Roger<br>
--<br>
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-- Martin Davis<br>
Senior Technical Architect<br>
Refractions Research, Inc.<br>
(250) 383-3022<br>
<br>
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<br>
-- <br>
Martin Davis<br>
Senior Technical Architect<br>
Refractions Research, Inc.<br>
(250) 383-3022<br>
<br>
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