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Yonik Seeley edited comment on SOLR2125 at 9/21/10 10:45 AM:

Ok Grant & I chatted and we figured out what's going wrong. We were calculating a box
the size that would completely fit inside the circle rather than viceversa. This was caused
by taking the distance and projecting it out to calculate the corners of the box. But the
distance given should really be to the side of the box... and the distance from the center
to the corner of the box should be greater (if the box is to completely encompass the circle).
The fix should be easy  the distance to the corner of the box is sqrt(2) * dist_to_side_of_box.
So internally we just need to multiply the distance by sqrt(2) before finding the corners.
Grant is coding up the fix and tests.
was (Author: yseeley@gmail.com):
Ok Grant & I chatted and we figured out what's going wrong. We were calculating a
box the size that would completely fit inside the circle rather than viceversa. This was
caused by taking the distance and projecting it out to calculate the corners of the box.
But the distance given should really be to the side of the box... and the distance from the
center to the corner of the box should be greater (if the box is to completely encompass the
circle).
The fix should be easy  the distance to the corner of the box is sqrt(2) * dist_to_size_of_box.
So internally we just need to multiply the distance by sqrt(2) before finding the corners.
Grant is coding up the fix and tests.
> 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
> Assignee: Grant Ingersoll
>
> 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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