[jira] [Updated] (LUCENE-6699) Integrate lat/lon BKD and spatial3d

["Nicholas Knize (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-6699?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nicholas Knize updated LUCENE-6699:
-----------------------------------
    Attachment: Geo3DPacking.java

I had thrown this code together a while ago before I put the GeoPointField / Geo3d integration work on hold.  This rough draft converts 3D LLA coordinates into ECEF cartesian coordinates using the WGS84 based non-iterative approach in GeoProjectionUtils (derived from the conversion approach illustrated in the Manual of Photogrammetry using 2 sin/cos and 1 sqrt). The ECEF cartesian coordinate is scaled to a unit spheroid (since this is presumably what Geo3D requires) and each of the 32 bits are interleaved (XYZ) akin to MortonEncoding. Decoding procedures are also provided. While this encoding is not nicely represented as a long (not yet convinced 21 bits per will preserve "acceptable" precision) it is BinaryDocValue friendly and enables a space partitioning/prefix coded approach similar to the way GeoPointField currently works. The Most-Significant 3 bits represent an Oct-Cell at the first level, next 3 for level 2, etc.


> Integrate lat/lon BKD and spatial3d
> -----------------------------------
>
>                 Key: LUCENE-6699
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6699
>             Project: Lucene - Core
>          Issue Type: New Feature
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>         Attachments: Geo3DPacking.java
>
>
> I'm opening this for discussion, because I'm not yet sure how to do
> this integration, because of my ignorance about spatial in general and
> spatial3d in particular :)
> Our BKD tree impl is very fast at doing lat/lon shape intersection
> (bbox, polygon, soon distance: LUCENE-6698) against previously indexed
> points.
> I think to integrate with spatial3d, we would first need to record
> lat/lon/z into doc values.  Somewhere I saw discussion about how we
> could stuff all 3 into a single long value with acceptable precision
> loss?  Or, we could use BinaryDocValues?  We need all 3 dims available
> to do the fast per-hit query time filtering.
> But, second: what do we index into the BKD tree?  Can we "just" index
> earth surface lat/lon, and then at query time is spatial3d able to
> give me an enclosing "surface lat/lon" bbox for a 3d shape?  Or
> ... must we index all 3 dimensions into the BKD tree (seems like this
> could be somewhat wasteful)?



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