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https://issues.apache.org/jira/browse/LUCENE-8615?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Rowe updated LUCENE-8615:
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Attachment: image.png
> Can LatLonShape's tessellator create more search-efficient triangles?
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>
> Key: LUCENE-8615
> URL: https://issues.apache.org/jira/browse/LUCENE-8615
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Adrien Grand
> Priority: Minor
> Attachments: 2-tessellations.png, re-tessellate-triangle.png
>
>
> The triangular mesh produced by LatLonShape's Tessellator creates reasonable
> numbers of triangles, which is helpful for indexing speed. However I'm
> wondering that there are conditions when it might be beneficial to run
> tessellation slightly differently in order to create triangles that are more
> search-friendly. Given that we only index the minimum bounding rectangle for
> each triangle, we always check for intersection between the query and the
> triangle if the query intersects with the MBR of the triangle. So the smaller
> the area of the triangle compared to its MBR, the higher the likeliness to
> have false positive when querying.
> For instance see the following shape, there are two ways that it can be
> tessellated into two triangles. LatLonShape's Tessellator is going to return
> either of them depending on which point is listed first in the polygon. Yet
> the first one is more efficient that the second one: with the second one,
> both triangles have roughly the same MBR (which is also the MBR of the
> polygon), so both triangles will need to be checked all the time whenever the
> query intersects with this shared MBR. On the other hand, with the first way,
> both MBRs are smaller and don't overlap, which makes it more likely that only
> one triangle needs to be checked at query time.
> !2-tessellations.png!
> Another example is the following polygon. It can be tessellated into a single
> triangle. Yet at times it might be a better idea create more triangles so
> that the overall area of MBRs is smaller and queries are less likely to run
> into false positives.
> !re-tessellate-triangle.png!
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