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https://issues.apache.org/jira/browse/SEDONA-178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17618877#comment-17618877
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Martin Andersson commented on SEDONA-178:
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I agree. I think option 3 is the way forward at least in the short term.
I did a version of option 3 here:
[https://github.com/apache/incubator-sedona/compare/master...umartin:incubator-sedona:sedona178_2]
I wanted to avoid ST_Buffer. I my opinion correctness should never be
compromised on. So the only valid solution with ST_Buffer is to execute the
original predicate after the join (like st_intersects(st_buffer(a, x + margin),
b) and st_distance(a, b) <= x).
# Margin is hard to calculate.
# ST_Buffer makes simple geometries a lot more complex so ST_Intersects might
be expensive to calculate. In postgis: select
st_npoints(st_buffer(st_geometryfromtext('POINT (1 1)'), 1)) = 33
My tweak is that I expanded the envelope instead of using st_buffer on the
actual geometry. That way the buffered geometry is always a simple square and
there is no need for a margin.
> Correctness issue in distance join queries
> ------------------------------------------
>
> Key: SEDONA-178
> URL: https://issues.apache.org/jira/browse/SEDONA-178
> Project: Apache Sedona
> Issue Type: Bug
> Reporter: Martin Andersson
> Priority: Major
>
> Hi,
> We are seeing erroneous results for some distance join queries.
>
> Case 1:
> The following query gives no output even though the distance between the
> geometries is 1.
> {{select *}}
> {{from (select ST_LineFromText('Linestring(1 1, 1 4)') as geom) a}}
> {{join (select st_point(1.0,5.0) as geom) b}}
> {{on st_distance(a.geom, b.geom) < 1.4}}
> I think the issue boils down to a misuse of/error in Circle class.
> DistanceJoinExec.scala:60 will create a Circle from the linestring and a
> radius of 1.4.
> Circle will compute the center point (1 2.5) and radius (1.5) for the
> linestring. The actual radius used is max(radius(linestring), 1.4). See
> Circle.java:80
> For the query to work the Circle needs a radius 1.4 _larger_ than the
> linestring. Like this:
> circle = new Circle(geom, 0.0);
> circle.setRadius(circle.getRadius() + 1.4)
>
> Case 2:
> The following query matches the geometries even though the distance is not
> less than 0.1. Actual distance is 1.
> {{select *}}
> {{from (select ST_LineFromText('Linestring(1 1, 1 3, 3 3)') as geom) a}}
> {{join (select st_point(2.0,2.0) as geom) b}}
> {{on st_distance(a.geom, b.geom) < 0.1}}
> Pseudo code for the join condition:
> new Circle(a.geom, 0.1).covers(b.geom)
> The circle does cover the point but the linestring is further away from the
> point than 0.1
>
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