siddharth raghuvanshi a écrit : > Hi, > > How is the spatial query related to distance is being carried on?? As > far as I have seen, jts topology suite resolves distance related > queries only by using the coordinates & has nothing to do with the srs > of the layer. So, how is OpenJump managing it?? Exactly the same way as JTS > > If projection of the layer is in EPSG:4326, parameter of distance is > in lat/lon, if it is in some other projection, unit of measurement may > be meter, feet etc. Yes, the distance parameter must be consistant with the srs unit > > In SpatialQueryPlugIn.java , it seems that parameter of the distance > query is independent of the coordinate reference system of the > layer. So, which class file of OpenJUMP is responsible for such > distance related spatial query?? Currently, you can associate a srs id to a layer, but there is no code in OpenJUMP to manage, transform, use this srs id. Spatial query is performed by classes SpatialQueryPlugIn, SpatialQueryExecuter and GeometryPredicate (from com.vividsolutions.jump.workbench.ui.plugin.analysis), but if you want to compute a "within distance query" with an input distance in meters and a dataset in geographic WGS srs, be aware that this is not just a matter unit conversion. Don't forget that geographic "degrees" have not a fixed size on every point of the Earth and in every direction.
reagards, Michaël > > Regards > Siddharth > > > ------------------------------------------------------------------------ > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > ------------------------------------------------------------------------ > > _______________________________________________ > Jump-pilot-devel mailing list > Jump-pilot-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel > ------------------------------------------------------------------------------ This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first _______________________________________________ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
