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Hi Lee,<br>
<br>
Unfortunately, I can't duplicate your error. I can
st_union(st_buffer(geom, 0.1)) no problem ...<br>
<tt>POLYGON ((<br>
586801.773149238 4951692.01936019, <br>
586801.773148314 4951692.01935961, <br>
586773.455669237 4951674.0093102, <br>
....</tt><br>
<br>
What version of GEOS are you running? As I've said, it works fine
for me running 3.2.2. Perhaps you need to upgrade?<br>
<br>
Cheers,<br>
Kevin<br>
<br>
On 9/15/2010 12:09 PM, Lee wrote:
<blockquote cite="mid:607100.83077.qm@web53505.mail.re2.yahoo.com"
type="cite">
<style type="text/css"><!-- DIV {margin:0px;} --></style>
<div style="font-family: garamond,new york,times,serif; font-size:
12pt;">okay so I plotted those points that were in the topology
exception error, and narrowed it down to two adjacent polygons.
So now I have:<br>
select st_union(st_buffer(the_geom,0.1)) from
base.current_assessment_parcel where gid in (36,37)<br>
(returns the topology exception)<br>
<br>
Checking out those two parcels, they seem legit in qgis /
arcview. (no weird nodes that I can see). <br>
<br>
Attached is the output from the following query: select gid,
st_asewkt(the_geom) from base.current_assessment_parcel where
gid in (36,37) <br>
I'm relatively newbie to postgis, so can't see what might be
causing this, if someone could look at this for me?<br>
<div> </div>
unfortunately, I am on vacation starting tonight, and won't be
available to provide further details. If the answer is "your
polygons are just messed up" then so be it. These are from
someone elses shapefile. Just want to help if this is indeed a
bug.<br>
<br>
Thanks for your help Kevin.<br>
Lee.<br>
<div><br>
</div>
<div style="font-family: garamond,new york,times,serif;
font-size: 12pt;"><br>
<div style="font-family: times new roman,new york,times,serif;
font-size: 12pt;"><font size="2" face="Tahoma">
<hr size="1"><b><span style="font-weight: bold;">From:</span></b>
Kevin Neufeld <a class="moz-txt-link-rfc2396E" href="mailto:kneufeld@refractions.net"><kneufeld@refractions.net></a><br>
<b><span style="font-weight: bold;">To:</span></b> PostGIS
Users Discussion
<a class="moz-txt-link-rfc2396E" href="mailto:postgis-users@postgis.refractions.net"><postgis-users@postgis.refractions.net></a><br>
<b><span style="font-weight: bold;">Sent:</span></b> Tue,
September 14, 2010 10:49:25 PM<br>
<b><span style="font-weight: bold;">Subject:</span></b>
Re: [postgis-users] unioning a buffer - bug?<br>
</font><br>
Interesting. Something sure sounds amiss. Are the results
null? Is
there anything usual occurring at the TopologyException
location? Is
your dataset large? Can you winnow it down to the few
polygons that
might be causing the problem (this may be just the polygons
around the
TopologyException location)? If so, you could paste the
representation
of the geometries in PasteBin or something so we can help
you isolate
the problem.<br>
<br>
Also, what version of GEOS do you have installed?<br>
SELECT PostGIS_Full_Version();<br>
<br>
Cheers,<br>
Kevin<br>
<br>
On 9/14/2010 6:03 AM, Lee wrote:
<blockquote type="cite">
<div style="font-family: garamond,new york,times,serif;
font-size: 12pt;">Hi
Kevin,<br>
<br>
I assumed I have no results because when I load one of
the working
queries as a view (eg. select st_buffer(the_geom,0.1))
in QGIS, or in
ArcGIS, I see all my results as I would expect, but when
I modify the
query to st_union(st_buffer()), all my parcels disappear
and I have a
blank canvas.<br>
<br>
Also, with st_isvalid(st_union(st_buffer(the_geom,0.1)))
returning null
(neither t nor f) I guess I just assumed. Anyways,
results for your
suggestions are inline, below. <br>
<br>
<div style="font-family: garamond,new york,times,serif;
font-size: 12pt;">Thanks
for your help. Any further ideas?<br>
<br>
Lee.<br>
<div style="font-family: times new roman,new
york,times,serif; font-size: 12pt;"><font size="2"
face="Tahoma">
<hr size="1"><b><span style="font-weight: bold;">From:</span></b>
Kevin Neufeld <a moz-do-not-send="true"
rel="nofollow" class="moz-txt-link-rfc2396E"
ymailto="mailto:kneufeld@refractions.net"
target="_blank"
href="mailto:kneufeld@refractions.net"><kneufeld@refractions.net></a><br>
<b><span style="font-weight: bold;">To:</span></b>
<a moz-do-not-send="true" rel="nofollow"
class="moz-txt-link-abbreviated"
ymailto="mailto:postgis-users@postgis.refractions.net"
target="_blank"
href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a><br>
<b><span style="font-weight: bold;">Sent:</span></b>
Tue, September
14, 2010 12:12:46 AM<br>
<b><span style="font-weight: bold;">Subject:</span></b>
Re:
[postgis-users] unioning a buffer - bug?<br>
</font><br>
How are you determining you have no results? <br>
<br>
Try:<br>
<tt>CREATE TABLE results AS<br>
SELECT st_union(st_buffer(the_geom,0.1)) as
the_geom <br>
FROM base.current_assessment_parcel;<br>
<br>
<span style="font-weight: bold; color: rgb(127, 0,
63);">NOTICE:
TopologyException: found non-noded intersection
between 586714
4.95189e+006, 586714 4.95189e+006 and 586714
4.95189e+006, 586739
4.9519e+006 586714 4.95189e+006</span><br
style="font-weight: bold; color: rgb(127, 0,
63);">
<span style="font-weight: bold; color: rgb(127, 0,
63);">Query
returned successfully with no result in 1078 ms.</span><br>
<br>
<br>
<br>
SELECT count(*) FROM results;<br>
<br>
<span style="font-weight: bold; color: rgb(127, 0,
63);">1</span><br>
<br>
SELECT ST_Summary(the_geom) FROM results;</tt><br>
<br>
<span style="color: rgb(127, 0, 63);">This returns
blank.</span><br>
<br>
<span style="font-family: monospace;"><br>
(snip)<br>
</span><br>
-- Kevin<br>
<br>
On 9/13/2010 7:07 AM, Lee wrote:
<blockquote type="cite">
<div style="font-family: garamond,new
york,times,serif; font-size: 10pt; color: rgb(3,
61, 33);"><font size="3"><span
style="font-weight: bold;">So after some
googling I see
similar problems, but no solutions posted.</span><br
style="font-weight: bold;">
<br style="font-weight: bold;">
<span style="font-weight: bold;">I am trying
to union a buffer, but
the query is returning no results. Here is
ultimately what I would
like to achieve:</span></font><br>
<br>
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0); font-weight: bold;">select
st_union(st_buffer(the_geom,0.1))
as
the_geom from
base.current_assessment_parcel</span><br>
<br>
<font size="3"><span style="font-weight: bold;">Here
are some
troubleshooting steps I have taken to try
narrow it down:</span></font><br>
<br style="color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">select
st_isvalid(the_geom)
a from base.current_assessment_parcel group by
a</span><br style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">TRUE</span><br
style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<br style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">select
st_isvalid(st_buffer(the_geom,0.1))
a from
base.current_assessment_parcel group by a</span><br
style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">TRUE</span><br
style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<br style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">select
st_isvalid(st_union(the_geom))
from base.current_assessment_parcel</span><br
style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">TRUE</span><br
style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<br style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">select
st_isvalid(st_union(st_buffer(the_geom,0.1)))
from
base.current_assessment_parcel</span><br
style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">NOTICE:
TopologyException:
found non-noded intersection between 586714
4.95189e+006, 586714 4.95189e+006 and 586714
4.95189e+006, 586739
4.9519e+006 586714 4.95189e+006</span><br
style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">Total
query
runtime: 859 ms.</span><br style="font-family:
Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">
<span style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
color: rgb(0, 0, 0);">1
row
retrieved.</span><br style="font-family:
Courier
New,courier,monaco,monospace,sans-serif;">
<font size="3"><span style="font-weight: bold;">(returns
blank
record)</span></font><br>
<br style="font-family: garamond,new
york,times,serif;">
<div style="font-family: Courier
New,courier,monaco,monospace,sans-serif;"><font
size="3"><span style="font-family:
garamond,new york,times,serif;
font-weight: bold;"> And
just
for fun</span></font><br>
<span style="color: rgb(0, 0, 0);">select
st_isvalid(st_buffer(st_union(the_geom),0.1))
a from
base.current_assessment_parcel</span><br
style="color: rgb(0, 0, 0);">
<span style="color: rgb(0, 0, 0);">TRUE</span><br
style="color: rgb(0, 0, 0);">
</div>
<font size="3"><br style="font-family: Courier
New,courier,monaco,monospace,sans-serif;
font-weight: bold;">
</font>
<div><font size="3"><span style="font-weight:
bold;">I guess my
next
step would be to try the snap to grid
functions, but the first query
above should work, shouldn't it?</span><br
style="font-weight: bold;">
<br style="font-weight: bold;">
<span style="font-weight: bold;">Any help
appreciated. Thanks.</span><br
style="font-weight: bold;">
<span style="font-weight: bold;">Lee</span></font><br>
</div>
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