Thomas Lutz a écrit : > I am facing big problems with polygons crossing the date line (from 180 > W to 180 E and back again) as well as polygons that have a pole inside > (something like Antarctica).
A possible way to workaround this problem is to define a new CRS with a prime meridian defined somewhere else than Greenwich, and use that new CRS for all geometries crossing the date line. Geotools allows you to put the prime meridian in whatever place you wish. However, current Geotools version requires that longitudes range from -180° to 180° on each side of this arbitrary prime meridian (we may fix that in a future Geotools version and allows 0 to 360° range, but we are not yet there). > If I understood the mail archived and the docs right, converting the > input points to WGS84 or even better to a sphere based coordinate system > should be no problem. Yes, as long as the input point use one of the supported projection (Cylindrical Mercator, Transverse Mercator, Lambert Conical, Stereographic, Orthographic and a few others I'm forgetting right now). If you face an unsupported projection, we may help you to add this projection to Geotools however. > Is geotools capable of calculating great circle, rhumblines and arcs on > the sphere ? I've read in the archive that I have to project and > reproject for this task, see > http://sourceforge.net/mailarchive/forum.php?thread_id=30124078&forum_id=12232 It depends what you want to do. For great circle and arcs on the great circle, the following should help (see the "orthodromicDistance" methods): http://javadoc.geotools.fr/snapshot/org/geotools/referencing/GeodeticCalculator.html > And last but not leas the "polar" shapes.. something like a closed > polygon with (170N 10W, 180N, 170W, 170N 10W), how can I implement this > in geotools ? I'm not sure, but maybe be using a Stereographic projections for such shapes? Martin ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Geotools-gt2-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
