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https://issues.apache.org/jira/browse/LUCENE-8220?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ignacio Vera reopened LUCENE-8220:
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I reopen the issue as I found another coplanarity that has not been addressed.
I think the fix is easy: when the points are assembled to create a concave
polygon, a check should be put in place to test that there are no coplanar
points. if there are, then throw a TileException as that is not legal.
In addition my test shows that building polygons with many points can be slow
with the new factory method. The reason is that it always filter points and
edges although that is only necessary when we tile the given polygon. Those
methods should be moved inside the if condition.
> GeoPolygon factory still shows problems with coplanar points
> ------------------------------------------------------------
>
> Key: LUCENE-8220
> URL: https://issues.apache.org/jira/browse/LUCENE-8220
> Project: Lucene - Core
> Issue Type: Bug
> Components: modules/spatial3d
> Reporter: Ignacio Vera
> Assignee: Karl Wright
> Priority: Major
> Fix For: 6.7, 7.4, master (8.0)
>
> Attachments: concave.jpg, concaveWithTiling.jpg,
> coplanarity-test.patch, coplanarity-test2.patch, factory.patch
>
>
> The attached patch contains two polygons that still shows problems with
> co-planar points. To better explain the issue I attached some images:
> 1) concave.jpg: This is the polygon we want to build. Note that we want to
> build the concave part, therefore the blue part is actually not part of the
> shape and the white part is the area cover by the shape.
> 2) concaveWithTiling.jpg: The algorithm of the polygon factory tries to tile
> the polygon using convex polygons. In our case it creates the three colored
> polygons on the image. What it remains is a concave polygon.
> The problem with this polygon is that the right edge of the concave polygon
> contains co-planar points. These points cannot be merged into a single plane
> because they have different properties (internal edges or shape edges).
> Because GeoConvexPolygon and GeoConcavePolygon cannot handle polygons with
> co-planar points, the polygon cannot be built.
> [~kwri...@metacarta.com], Is it possible to make this polygons support such
> an extreme case?
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