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From "Yonik Seeley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (SOLR-2125) Spatial filter is not accurate
Date Tue, 21 Sep 2010 03:42:32 GMT

    [ https://issues.apache.org/jira/browse/SOLR-2125?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12912827#action_12912827
] 

Yonik Seeley commented on SOLR-2125:
------------------------------------

bq. Distance using the Haversine function is extremely sensitive to what spatial reference
system the data was recorded in. WGS84 isn't particular great with long distances.

I know nothing on this topic, but an error of 45% at 200 km?  I'm pretty certain that there
is a bug not having to do with the accuracy of spatial reference systems here.

> Spatial filter is not accurate
> ------------------------------
>
>                 Key: SOLR-2125
>                 URL: https://issues.apache.org/jira/browse/SOLR-2125
>             Project: Solr
>          Issue Type: Bug
>          Components: Build
>    Affects Versions: 1.5
>            Reporter: Bill Bell
>
> The calculations of distance appears to be off.
> Note: "The radius of the sphere to be used when calculating distances on a sphere (i.e.
haversine). Default is the Earth's mean radius in kilometers (see org.apache.solr.search.function.distance.Constants.EARTH_MEAN_RADIUS_KM)
which is set to 3,958.761458084784856. Most applications will not need to set this."
> The radius of the earth in KM is  6371.009 km (≈3958.761 mi).
> Also filtering distance appears to be off - example data:
> 45.17614,-93.87341 to 44.9369054,-91.3929348 Approx 137 miles Google. 169 miles = 220
kilometers
> http://....../solr/select?fl=*,score&start=0&rows=10&q={!sfilt%20fl=store_lat_lon}&qt=standard&pt=44.9369054,-91.3929348&d=280&sort=dist(2,store,vector(44.9369054,-91.3929348))
asc 
> Nothing shows. d=285 shows results. This is off by a lot.
> Bill

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