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https://issues.apache.org/jira/browse/LUCENE-8220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16412476#comment-16412476
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Ignacio Vera commented on LUCENE-8220:
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I think we cannot avoid this colinearity. In the example provided it is clear
there is no alternative on how the polygon can be tiled. The colinear points
must be added.
I think the definition of an edge can be changed. Currently it is a sided plane
with a start and end point and an internal flag. It can be changed to a sided
plane with two or more points with corresponding internal flags.
When replacing edges we can add the new edge or add the point to an existing
edge if colinear.
BUT then you build convex and concave polygons with co-planar points where it
breaks.
> 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
> Attachments: concave.jpg, concaveWithTiling.jpg,
> coplanarity-test.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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