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Posted to dev@lucene.apache.org by "Michael McCandless (JIRA)" <ji...@apache.org> on 2016/04/01 01:25:25 UTC
[jira] [Updated] (LUCENE-7158) Haversin should use the earth's mean
radius, not its max (equitorial)?
[ https://issues.apache.org/jira/browse/LUCENE-7158?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michael McCandless updated LUCENE-7158:
---------------------------------------
Attachment: LUCENE-7158.patch
Initial patch, however some geo3d tests are angry about the change from 6371009.0 to 6371008.7714 as the mean ... maybe [~daddywri] can help fix them?
A surprising number of places cared greatly about the exact earth's radius ;)
> Haversin should use the earth's mean radius, not its max (equitorial)?
> ----------------------------------------------------------------------
>
> Key: LUCENE-7158
> URL: https://issues.apache.org/jira/browse/LUCENE-7158
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Michael McCandless
> Attachments: LUCENE-7158.patch
>
>
> Across our spatial modules we seem to disagree about the earth's radius when we model it as a sphere.
> I think in our haversin implementation we use equitorial (maximum) radius, but maybe in spatial3d we use the earth's mean radius.
> I think mean makes more sense: the earth is actually a squashed sphere, so it's polar radius is shorter than its equitorial radius.
> I think it's important, when we model the earth as a sphere, that we pick one radius and try to use that one consistently?
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