[geos-devel] RE: [GEOS] #468: Geometry breaks valid() and
buffer(): "Assertion failed: (0), function query, file
AbstractSTRtree.cpp, line 286"
Sandro Santilli
strk at keybit.net
Sat Aug 20 07:41:30 EDT 2011
Please upload the smallest geometry with which you can
reproduce the issue to the bug item you opened already.
The error reveals a bogus use of the library.
Since all code is internal to the library, this should never happen.
I can think of two possibilities:
1) memory corruption (valgrind could help you figure that out)
2) bogus compilation (any warnings at build time?)
I'm assuming it'll work for me, but didn't really test.
BTW: make sure to include version in your ticket, and if you didn't
make sure to test with latest GEOS release, and possibly with SVN too
(I know I'm asking a lot, but that's what I'd do if I had time to deal
with this).
Oh, last thing: JTS does not have the consistency check (that a
childBoundable is either an AbstractNode or an ItemBoundable) but
just lets go in that case. It could explain why it doesn't error
out (but doesn't explain what ended up in the childBoundables...).
--strk;
On Fri, Aug 19, 2011 at 09:45:04AM -0700, Christopher DeMars wrote:
> I initially wasn't sure if the failure was caused by a particular
> geometry formation or due to the size of the dataset. I have since
> tried other county layers from the same source (California Department
> of Water Resources) and got the same error after processing a small
> number of polygons, so whatever the polygon encoding issue, it is
> fairly common in this dataset. I can extract other example polygons if
> anyone is interested.
>
> --Christopher
>
> On Fri, Aug 19, 2011 at 8:24 AM, Martin Davis <mtnclimb at telus.net> wrote:
> > Good to have the problem narrowed down.
> >
> > There's nothing obviously wrong with the polygon, at least from the JTS
> > perspective. Perhaps Sandro can shed some light on the issue...
> >
> > On 8/19/2011 7:03 AM, Christopher DeMars wrote:
> >
> > Thank you Mr. Davis for your attention,
> >
> > I tried your suggestion of buffering elements individually then
> > merging the buffers. I buffered several elements without issue, then
> > got the same program stopping error message as before. On the plus
> > side, I did isolate a polygon that was crashing things. Attached is
> > the wkt and wkb of that polygon.
> >
> > --Christopher
> >
> >
> > On Thu, Aug 18, 2011 at 8:53 PM, Martin Davis <mtnclimb at telus.net> wrote:
> >
> > Incidentally, this is one of those cases where buffering by unioning the
> > buffers of the components far outperforms the straight buffer (for distance
> > = 100, 10 s vs 70 s).
> >
> > This is something you might be able to try, if your data model permits it.
> > Split the geometry into its components, and process them all separately.
> > This should give better performance, and may avoid the GEOS issues.
> >
> > On 8/18/2011 8:43 PM, Martin Davis wrote:
> >
> > I have tested this in JTS 1.12, and can confirm that both isValid and buffer
> > work correctly. The buffer operation does take quite a while and requires a
> > significant amount of memory.
> >
> > So the geometry is fine. There may be some issues with GEOS.
> >
> > On 8/18/2011 3:44 PM, Christopher DeMars wrote:
> >
> > Since the ticket upload function is limited to 256Kb, I thought I
> > would try to send an example file via this list.
> >
> > Attached is water1.wkb, a multipolygon that fubars GEOS buffer or
> > valid functions. I can supply water2 and/or either file as wkt.
> >
> > Thank you for any help you can offer,
> > --Christopher
> >
> >
> > ---------- Forwarded message ----------
> > From: GEOS <geos-trac at osgeo.org>
> > Date: Thu, Aug 18, 2011 at 3:08 PM
> > Subject: [GEOS] #468: Geometry breaks valid() and buffer(): "Assertion
> > failed: (0), function query, file AbstractSTRtree.cpp, line 286"
> > To:
> >
> >
> > #468: Geometry breaks valid() and buffer(): "Assertion failed: (0), function
> > query, file AbstractSTRtree.cpp, line 286"
> > ------------------------+---------------------------------------------------
> > Reporter: chdemars | Owner: strk
> > Type: defect | Status: new
> > Priority: major | Milestone: 3.3.1
> > Component: Core | Version: 3.3.0
> > Severity: Unassigned | Keywords:
> > ------------------------+---------------------------------------------------
> > GEOS is pretty far down in the software stack I'm using, but it looks like
> > my program stopping error lies there.
> >
> > Software being used:
> > geos-config --version 3.3.0
> > I'm using GeoDjango and PostGIS on top of GEOS with development taking
> > place on Mac OSX
> >
> > Geometry source:
> > original source is:
> > http://www.water.ca.gov/landwateruse/docs/landusedata/shapes/04bu.zip
> >
> > After loading that (and the other DWR land use files) into my
> > PostGIS/GeoDjango database I extracted all the water features using:
> > water = DWRlanduse.objects.filter(class1__contains='NW',
> > survey_area__contains='BUTTE COUNTY').collect()
> >
> > I have attached the wkb and wkt output of the above with water1 using
> > .unionagg() and water2 using .collect() to produce a MultiPolygon and
> > GeometryCollection respectively. Both produce failure.
> >
> > If I try to use .buffer() or .valid() functions on either water1 or water2
> > I get the same failure:
> > Assertion failed: (0), function query, file AbstractSTRtree.cpp, line 286
> > which says one of the 'childBoundables' is of an unsupported type.
> > Functions like area or centroid work fine.
> >
> > I would like to know if the error is a problem with GEOS and/or a problem
> > with the geometry. Regardless of the source of error, I would also like to
> > know how to go about fixing it.
> >
> > Thank you for your time and efforts,
> > --Christopher
> >
> > --
> > Ticket URL: <http://trac.osgeo.org/geos/ticket/468>
> > GEOS <http://geos.refractions.net/>
> > GEOS (Geometry Engine - Open Source) is a C++ port of the Java
> > Topology Suite (JTS).
> >
> >
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--
() Free GIS & Flash consultant/developer
/\ http://strk.keybit.net/services.html
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