[postgis-tickets] [PostGIS] #3329: Topology population regression

[PostGIS]

#3329: Topology population regression
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  Reporter:  strk      |      Owner:  strk
      Type:  defect    |     Status:  new
  Priority:  blocker   |  Milestone:  PostGIS 2.2.1
 Component:  topology  |    Version:  2.2.x
Resolution:            |   Keywords:
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Comment (by aperi2007):

 Hi strk,
 I add a new packege with a really reduced dataset to produce the
 intersection issue.

 Also an image to explain the question:

 [[Image(img-ante.gif)]]

 The topology has the two edge 58 and 59 loaded.
 Has you can notice the edge 58 is at right of the 59 edge.
 Also you can notice the new line to add to the topology (red line) is at
 left side.

 The procedure find before the 58 edge and try to link the new line (red)
 to the 58 edge and this trigger the intersection with the 59 edge.

 ut perhaps thre is more.
 Infact say-ing that the 58 edge is find before the 59 edge could be not
 sufficient to explain why it is choose.
 Infact I remenber that in the core of geos some year ago was done an
 enhancement to allow the geos snap to find the nearest feature not only
 the first feature under the snap limit.

 (see the geos ticket [https://trac.osgeo.org/geos/ticket/501])

 If this code is still in geos and active (and is used in this procedure)
 the explanation is not only that the 58 edge is found before the 59 edge
 but instead is that the 58 edge has a vertex nearest to the newline (red)
 rather than the 59 edge.

 The image show this kind of use-case, as you can see the vertex (blue) of
 the 58 edge is near to the red line rather than the two vertex s of the 59
 edge.

 This could explain why the procedure choose the 58 edge instead of the 59
 edge and to so the intersection fail.

 regards.

 Andrea.

 If this enhancemente for snap geos is still in geos core the explanation
 to why

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/3329#comment:13>
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