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https://issues.apache.org/jira/browse/SIS-45?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13404715#comment-13404715
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Peter Karich edited comment on SIS-45 at 3/7/13 8:40 PM:
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I've improved the query speed by additional 30% ! Now the distance is only an
approximation (but a good one for 'shorter' distances) based on the spherical
projection:
http://en.wikipedia.org/wiki/Geographical_distance#Spherical_Earth_projected_to_a_plane
Here is the java code:
https://github.com/graphhopper/graphhopper/blob/master/src/main/java/com/graphhopper/util/DistancePlaneProjection.java
Here is some more info:
http://stackoverflow.com/a/11261385/194609
was (Author: peathal):
I've improved the query speed by additional 30% ! Now the distance is only
an approximation (but a good one for 'shorter' distances) based on the
spherical projection:
http://en.wikipedia.org/wiki/Geographical_distance#Spherical_Earth_projected_to_a_plane
Here is the java code:
https://github.com/karussell/GraphHopper/blob/master/core/src/main/java/de/jetsli/graph/util/ApproxCalcDistance.java
Here is some more info:
http://stackoverflow.com/a/11261385/194609
> Performance improvement of queryByPointRadius
> ---------------------------------------------
>
> Key: SIS-45
> URL: https://issues.apache.org/jira/browse/SIS-45
> Project: Spatial Information Systems
> Issue Type: Improvement
> Components: distance functions
> Reporter: Peter Karich
> Assignee: Chris A. Mattmann
> Fix For: 0.3
>
>
> If I didn't make a mistake a search with the normal distance method took
> ~2.4s and with this distance method it takes only about 0.7s:
> {code}
> public static double getHaversineDistance(double fromLat, double fromLon,
> double toLat, double toLon) {
> double dLat = Math.toRadians(toLat - fromLat);
> double dLon = Math.toRadians(toLon - fromLon);
> double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
> + Math.cos(Math.toRadians(fromLat)) *
> Math.cos(Math.toRadians(toLat)) * Math.sin(dLon / 2) * Math.sin(dLon / 2);
> return EARTH_RADIUS * 2 * Math.asin(Math.sqrt(a));
> }
> {code}
> Also one should think about normalizing the distance before the search so
> that one does not need the whole last line which should give further speed
> improvements.
> I'm still unsure why it takes roughly the same time in my example for 10km,
> 20km and 40kmm where at every step a lot more nodes are involved. Normally I
> would say the mode nodes - the more comparisons it'll take and the slower it
> should get. But it doesn't. Probably I'm measuring wrong?
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