Hi Randy, Robert already replied to your previous email ... maybe you missed it?
Mike McCandless http://blog.mikemccandless.com On Sat, Jun 11, 2016 at 4:05 PM, Randy Tidd <r...@tidd.cc> wrote: > Thanks for the help you’ve already given me on getting search with > LatLonPoint working, the basics are working great and with great > performance. > > I did some testing on some edge cases and discovered that indexing and > searching for points at the minimum and maximum latitude and longitude are > not working as I expected. I’d appreciate some feedback on this. > > Take for example the point (0.0, 180.0) which is in the Pacific ocean at > latitude = 0.0 and longitude = 180.0. If we create a grid of 9 points > centered on this location (“tic tac toe” layout) with an offset of 0.1 the > coordinates would be: > > (0.1, -179.9), (0.0, -179.9), (-0.1, -179.9), (0.1, 180.0), (0.0, 180.0), > (-0.1, 180.0), (0.1, 179.9), (0.0, 179.9), (-0.1, 179.9) > > The max longitude is 180, so if you move 0.1 degree east the next > longitude is actually -179.9 rather than 180.1, it wraps around. > > If I then create a square that encompasses these points using an offset of > 1.0 (larger than the 0.1 for the indexed points) that polygon would have > these endpoints: > > (-1.0, 179.0}, (1.0, 179.0), (1.0, -179.0), (-1.0, -179.0), (-1.0, 179.0) > > The first and last point are the same so that this is a closed polygon. > > When I index these points with LatLonPoint and do a search with > LatLonPoint.newPolygonQuery() it does not return any results, which isn’t > what I expected. > > However, if I index a grid of points around (0.0, 0.0) and search with > this polygon, they are returned by this search, which I don’t believe is > correct. It is as if the search thinks that the point (0.0, 0.0) is > between the points (0.0, 179) and (0.0, -179) which I don’t think is > correct. Longitude 0.0 and 180.0 are on opposite sides of the globe. > > I see the same behavior with data centered at these points: > > (90.0, -180.0) > (90.0, 0.0) > (90.0, 180.0) > (0.0, -180.0) > (0.0, 180.0) > (-90.0, -180.0) > (-90.0, 0.0) > (-90.0, 180.0) > > However, using more “normal” points such as (44.4605, -110.8281) this test > works fine. > > So I’m wondering if there is a problem with the search handling polygons > that span the latitude and longitude boundaries, or if maybe I am just not > thinking about this right to begin with. I can post sample code if that > would be helpful. Thanks for any assistance / input. > > Randy > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > >
