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https://issues.apache.org/jira/browse/LUCENE-6450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14539533#comment-14539533
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Karl Wright commented on LUCENE-6450:
-------------------------------------
Thinking about this further, I think that the simplicity of the GeoPointField
solution is based on two things:
(1) A good binary packing of a geohash value of a fixed depth
(2) The ability to reconstruct the lat/lon from the geohash value directly
For a Geo3d equivalent, nobody to date has come up with a decent (x,y,z)
geohash with the right locality properties. I'm not certain how important
those locality properties actually *are* for GeoPointField, though. If they
are important, then effectively we'd need to pack the *same* lat/lon based
geohash value that GeoPointField uses, but have a lightning fast way of
converting it to (x,y,z). A lookup table would suffice but would be huge at
9mm resolution. :-) Adjusting the resolution would be a potential solution.
If locality is *not* needed, then really a "geohash" would be any workable
fixed-resolution binary encoding of the (x,y,z) values of any given lat/lon.
> Add simple encoded GeoPointField type to core
> ---------------------------------------------
>
> Key: LUCENE-6450
> URL: https://issues.apache.org/jira/browse/LUCENE-6450
> Project: Lucene - Core
> Issue Type: New Feature
> Affects Versions: Trunk, 5.x
> Reporter: Nicholas Knize
> Priority: Minor
> Attachments: LUCENE-6450-5x.patch, LUCENE-6450-TRUNK.patch,
> LUCENE-6450.patch, LUCENE-6450.patch, LUCENE-6450.patch, LUCENE-6450.patch
>
>
> At the moment all spatial capabilities, including basic point based indexing
> and querying, require the lucene-spatial module. The spatial module, designed
> to handle all things geo, requires dependency overhead (s4j, jts) to provide
> spatial rigor for even the most simplistic spatial search use-cases (e.g.,
> lat/lon bounding box, point in poly, distance search). This feature trims the
> overhead by adding a new GeoPointField type to core along with
> GeoBoundingBoxQuery and GeoPolygonQuery classes to the .search package. This
> field is intended as a straightforward lightweight type for the most basic
> geo point use-cases without the overhead.
> The field uses simple bit twiddling operations (currently morton hashing) to
> encode lat/lon into a single long term. The queries leverage simple
> multi-phase filtering that starts by leveraging NumericRangeQuery to reduce
> candidate terms deferring the more expensive mathematics to the smaller
> candidate sets.
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