[ https://issues.apache.org/jira/browse/SOLR2125?page=com.atlassian.jira.plugin.system.issuetabpanels:commenttabpanel&focusedCommentId=12913244#action_12913244
]
Bill Bell commented on SOLR2125:

OK so that makes sense. Youa re using distance at 45 degrees. So the eastwest would not extend
far enough.
Using http://en.wikipedia.org/wiki/Pythagorean_theorem would help on the eastwest case, but
circle or ellipses is MUCH better.
Although extending the 45 degree out would be a conservative estimate. And since we usually
sort by distance asc, those extra points would be in the result set but at the end of the
list. (this is an improvement  again not at good as ellipses).
You need a quick function that tells you "is this lat,long in the circle / ellipses or not".
A range [X to Y] will not get you that. You need to use hsin().
On potential:
1. Do range select using points http://janmatuschek.de/LatitudeLongitudeBoundingCoordinates
(Lat => 1.2393 AND Lat <= 1.5532) AND (Lon >= 1.8184 AND Lon <= 0.4221)
2. Check those points for distance "in the ellipses". http://janmatuschek.de/LatitudeLongitudeBoundingCoordinates
acos(sin(1.3963) * sin(Lat) + cos(1.3963) * cos(Lat) * cos(Lon  (0.6981))) <= 0.1570;
That should make it fast and simplify the calculations.
> 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

This message is automatically generated by JIRA.

You can reply to this email to add a comment to the issue online.

To unsubscribe, email: devunsubscribe@lucene.apache.org
For additional commands, email: devhelp@lucene.apache.org
