[jira] [Comment Edited] (LUCENE-7229) Improve Polygon.relate

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

    [ https://issues.apache.org/jira/browse/LUCENE-7229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15246451#comment-15246451 ] 

Nicholas Knize edited comment on LUCENE-7229 at 4/18/16 8:17 PM:
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bq. There needs to be 4 line checks there since the box has 4 edges, but that code only checks 2.

That's a separate short-cut. After the line endpoints are checked against the rectangle it checks if the line crosses a diagonal of the rectangle. This way only the 2 diagonal lines of the rectangle need to be checked, not all 4.




was (Author: nknize):
bq. There needs to be 4 line checks there since the box has 4 edges, but that code only checks 2.

That's a separate short-cut. After the line endpoints are checked against the rectangle it checks if the line crosses a diagonal of the rectangle. This way only 2 lines of the rectangle need to be checked, not all 4. 

> Improve Polygon.relate
> ----------------------
>
>                 Key: LUCENE-7229
>                 URL: https://issues.apache.org/jira/browse/LUCENE-7229
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Robert Muir
>         Attachments: LUCENE-7229.patch, LUCENE-7229.patch
>
>
> This method is currently quite slow and in many cases does more work than is required. The speed actually directly impacts queries (tree traversal) and bounds grid size to something tiny making it less effective.
> I think we should replace it line intersections based on orientation methods described here http://www.cs.berkeley.edu/~jrs/meshpapers/robnotes.pdf and https://www.cs.cmu.edu/~quake/robust.html
> For one, a naive implementation is considerably faster than the method today: both because it reduces the cost of BKD tree traversals and also because it makes grid construction cheaper. This means we can increase its level of detail with similar or lower startup cost. Now its more like a Mario Brothers 2 picture of your polygon instead of Space Invaders.
> Synthetic polygons from luceneUtil
> ||vertices||old QPS||new QPS||old startup cost||new startup cost||
> |50|20.4|21.7|1ms|1ms|
> |500|11.2|14.4|5ms|4ms|
> |1000|7.4|10.0|9ms|8ms|
> Real polygons (33 london districts: http://data.london.gov.uk/2011-boundary-files)
> ||vertices||old QPS||new QPS||old startup cost||new startup cost||
> |avg 5.6k|4.9|8.6|94ms|85ms|
> But I also like using this method because its possible to extend it to remove floating point error completely in the future with techniques described in those links. This may be necessary if we want to do smarter things (e.g. not linear time).



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