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

["Karl Wright (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-6699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14644248#comment-14644248 ] 

Karl Wright edited comment on LUCENE-6699 at 7/28/15 11:23 AM:
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bq. 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?

Ok, so now you have me confused a bit as to what your requirements are for BKD.  If you want to split the globe up into lat/lon rectangles, and use BKD that way to descend, then obviously you'd need points to be stored in lat/lon.  But that would make less sense for geospatial3d, because what you're really trying to do is assess membership in a shape, or distance also in regards to a shape, both of which require (x,y,z) not lat/lon.  Yes, you can convert to (x,y,z) from lat/lon, but the conversion is relatively expensive.

Instead, I could imagine just staying natively in (x,y,z), and doing your splits in that space, e.g. split in x, then in y, then in z.  So you'd have a GeoPoint3D which would pack (x,y,z) in a format you could rapidly extract, and a splitting algorithm that would use the known ranges for these values.  Does that make sense to you?  Would that work with BKD?



was (Author: kwright@metacarta.com):
bq. 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?

Ok, so now you have me confused a bit as to what your requirements are for BKD.  If you want to split the globe up into lat/lon rectangles, and use BKD that way to descend, then obviously you'd need points to be stored in lat/lon.  But that would make less sense for geospatial3d, because what you're really trying to do is assess membership in a shape, or distance also in regards to a shape, both of which require (x,y,z) not lat/lon.  Yes, you can convert to (x,y,z) from lat/lon, but the conversion is relatively expensive.

Instead, I could imagine just staying natively in (x,y,z), and doing your splits in that space, e.g. split in x, then in y, then in z.  So you'd have a GeoPoint3D which would pack (x,y,z) in a format you could rapidly extract, and a splitting algorithm that would use the known ranges for these values.  Does that make sense to you?  Would that work with BKD?


> 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
>
> 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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