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https://issues.apache.org/jira/browse/LUCENE-7970?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16180796#comment-16180796
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Karl Wright edited comment on LUCENE-7970 at 9/26/17 10:32 PM:
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[~ivera], the accuracy value is a linear distance on the unit spheroid, *not*
an angular distance.
More precisely, the "accuracy" is defined as the maximum linear distance
between any point on the surface circle and planes that describe the
GeoExactCircle shape. Since the radius of earth is 6,371,000 meters, an
accuracy of 1e-6 corresponds to 6.3 meters. For an accuracy of 1.0 meters,
you'd need a value of 1.6e-7. Does that make sense?
I too want to apologize; I've rarely been busier and my interruptions have been
having interruptions. But I'm taking Thursday and Friday as vacation days so
maybe I can spend a little more time finishing up some of these issues.
was (Author: [email protected]):
[~ivera], the accuracy value is a linear distance on the unit spheroid, *not*
an angular distance. So an accuracy of 1e-6 corresponds roughly to 1 meter
distance on the earth's surface.
> Add a Geo3d shape that models an exact circle, even when the planet model is
> not a sphere
> -----------------------------------------------------------------------------------------
>
> Key: LUCENE-7970
> URL: https://issues.apache.org/jira/browse/LUCENE-7970
> Project: Lucene - Core
> Issue Type: Improvement
> Components: modules/spatial3d
> Reporter: Ignacio Vera
> Assignee: Karl Wright
> Attachments: circle.jpg, LUCENE-7970-exact.diff, LUCENE_7970.patch,
> LUCENE-7970.patch, LUCENE-7970-proposed.patch,
> LUCENE-7970_testBearingPoint.patch
>
>
> Hi [~Karl wright],
> How circles are currently build do not behave very well when the planet model
> is not an sphere. when you are close to the border in WGS84 you might get
> false positves or false negatives when checking if a point is WITHIN. I think
> the reason is how the points to generate the circle plane are generated which
> assumes a sphere.
> My proposal is the following:
> Add a new method to PlanetModel:
> public GeoPoint pointOnBearing(GeoPoint from, double dist, double bearing);
> Which uses and algorithm that takes into account that the planet might not be
> spherical. For example Vincenty's formulae
> (https://en.wikipedia.org/wiki/Vincenty%27s_formulae).
> Use this method to generate the points for the circle plane. My experiments
> shows that this approach removes false negatives in WGS84 meanwhile it works
> nicely in the Sphere.
> Does it make sense?
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