On 6/4/08, Shane Harrelson <[EMAIL PROTECTED]> wrote: > With the recent discussions on R-Tree's and spherical coordinates (i.e. > latitude and longitude), I was wondering how boundary conditions would be > handled. > If I choose a location on the equator as far from the prime meridian as > possible, and try to query for all the locations "near" that, > within a given bounding rectangle, will it only return locations in 1 > direction? > > For example: > > Choose starting location 0.0 lat, 180.0 long. This is also the equivalent > location of 0.0 lat, -180.0 long, and very close to 0.0, -179.999. > If I choose a bounding rectangle of say 1 degree (-1,179; 1,179; -1,-179; > 1,-179), since the R-Tree algorithms are using > planar-coordinate distances (or areas), want this miss locations across the > boundary, like 0.0, -179.999? > > How is this typically handled?
Project the data to Cartesian coordinates first. Which means, integrate Proj.4 into SQLite. The next step after that would be to integrate Geos, and everything will be copacetic. > -Shane > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > -- Puneet Kishor http://punkish.eidesis.org/ Nelson Institute for Environmental Studies http://www.nelson.wisc.edu/ Open Source Geospatial Foundation (OSGeo) http://www.osgeo.org/ _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
