[geos-devel] Re: [GEOS] #458: Polygonizer robustness failure

[GEOS]

#458: Polygonizer robustness failure
------------------------+---------------------------------------------------
 Reporter:  strk        |       Owner:  geos-devel@…              
     Type:  defect      |      Status:  new                       
 Priority:  major       |   Milestone:  3.3.1                     
Component:  Default     |     Version:  3.3.0                     
 Severity:  Unassigned  |    Keywords:                            
------------------------+---------------------------------------------------
Description changed by strk:

Old description:

> A simple multiline containing 3 linestrings of 2,5 and 6 vertices, all
> sharing the same endpoints (2 nodes in total in the topology)
> fail to be polygonized in floating precision, while successfully
> polygonize as 2 rings with a precision of 1e-11.
>
> See http://trac.osgeo.org/postgis/ticket/1115 for original report.
>
> In the geometry with 5 vertices, distance between first and second vertex
> and between forth and fifth vertex is 2.3283064365387e-10.
>
> The polygonizer returns _no_ rings.
> Dropping one of the close-by vertices (not on the topology node)
> makes the polygonizer return _1_ ring.
> Dropping both makes it succeed in returning _2_ rings as it should.
>
> Simplified MULTILINESTRING input follows:
> {{{
> 010500000003000000010200000002000000555C8F42354A3A41A4703D6A1E445241CCCCCC0C474A3A415C8FC2851E445241010200000005000000555C8F42354A3A41A4703D6A1E445241545C8F42354A3A41A4703D6A1E445241409B06043D4A3A415860C1CC1C445241CDCCCC0C474A3A415C8FC2851E445241CCCCCC0C474A3A415C8FC2851E445241010200000006000000CCCCCC0C474A3A415C8FC2851E445241C4F5289C4B4A3A415C8FC2C52B445241B533D71C964A3A418EAD7CBD1A4452412085EB91284A3A417A14AE2719445241285C8F42354A3A41A4703D6A1E445241555C8F42354A3A41A4703D6A1E445241
> }}}
> }}}

New description:

 A simple multiline containing 3 linestrings of 2,5 and 6 vertices, all
 sharing the same endpoints (2 nodes in total in the topology)
 fail to be polygonized in floating precision, while successfully
 polygonize as 2 rings with a precision of 1e-11.

 See http://trac.osgeo.org/postgis/ticket/1115 for original report.

 In the geometry with 5 vertices, distance between first and second vertex
 and between forth and fifth vertex is 2.3283064365387e-10.

 The polygonizer returns _no_ rings.
 Dropping one of the close-by vertices (not on the topology node)
 makes the polygonizer return _1_ ring.
 Dropping both makes it succeed in returning _2_ rings as it should.

 Simplified MULTILINESTRING input follows:
 {{{
 010500000003000000010200000002000000555C8F42354A3A41A4703D6A1E445241CCCCCC0C474A3A415C8FC2851E445241010200000005000000555C8F42354A3A41A4703D6A1E445241545C8F42354A3A41A4703D6A1E445241409B06043D4A3A415860C1CC1C445241CDCCCC0C474A3A415C8FC2851E445241CCCCCC0C474A3A415C8FC2851E445241010200000006000000CCCCCC0C474A3A415C8FC2851E445241C4F5289C4B4A3A415C8FC2C52B445241B533D71C964A3A418EAD7CBD1A4452412085EB91284A3A417A14AE2719445241285C8F42354A3A41A4703D6A1E445241555C8F42354A3A41A4703D6A1E445241
 }}}

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Ticket URL: <http://trac.osgeo.org/geos/ticket/458#comment:2>
GEOS <http://geos.refractions.net/>
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).