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]
Bill Bell commented on SOLR2125:

Yes there is still a bug.
Most of what I was saying was right. I just did a quick maps.google.com  click directions
 and then put the 2 lat,long in both fields.
137 miles = 220.480128 kilometers (Google)
196.6km using http://www.movabletype.co.uk/scripts/latlong.html
See on map: http://www.movabletype.co.uk/scripts/latlongmap.html?lat1=45.176140&long1=93.873410&lat2=44.936905&long2=91.392935
Distance: 196.6 km
Initial bearing: 096°53′44″
Final bearing: 098°39′05″
Midpoint: 45°03′48″N, 092°37′50″W
As the crow flies should be less distance.
I even used the JS function on http://www.movabletype.co.uk/scripts/latlong.html:
function toRad(a) {
return (a*Math.PI/180);
};
function hsin(lat1,lon1,lat2,lon2) {
var R = 6371; // km
var dLat = toRad(lat2lat1);
var dLon = toRad(lon2lon1);
var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) *
Math.sin(dLon/2) * Math.sin(dLon/2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1a));
var d = R * c;
return d;
};
As a Javascript function  while looping through the results. Since I cannot find a way to
output the distance automagically from the XML coming back from SOLR.
<script>document.write(hsin(lat,lon,solr.lat,solr.lom));</script>
I kept playing with d=<km> to see when the filter is not longer showing on the results
at while value.
&sort=dist(2,store,vector(44.9369054,91.3929348)) asc
d=285 shows.
d=284 does not show.
> Spatial filter is not accurate
> 
>
> Key: SOLR2125
> URL: https://issues.apache.org/jira/browse/SOLR2125
> 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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