Hi Siddharth, > Suppose I have a layer in epsg:4326 belonging to India... now I have > converted it into EPSG:24380 by using coordinate transform plugin, > the ogcwkt representation of EPSG:24380 is Sorry, I'm not sure how the coordinate transformation plugin works exactly, but if coordinates displayed by OpenJUMP are now projected coordinates (coordinates are displayed in the status bar), it means that distance parameter has now to be input in meters. > So, what is actually happening here?? Does after applying coordinate > transformation, the whole geometry of the layer change?? Ya probably, maybe someone experienced with this plugin can confirm. > Actually I am not understanding how crs of a layer is associated with its > geometry. Please help. AFAIK, OpenJUMP just make it possible to tag a layer (or a geometry) with a srs identifier. You can consider it as a metadata. What is displayed is what is in your dataset. I think coordinate transformation plugin change actual coordinates of feature geometries. Anyway, it's quite easy to know if actual data you're querying are in a projected coordinate system or in a geographic coordinate system, just look at the status bar or edit a feature geometry.
Regards, Michaël > Regards > Siddharth > > > > 2010/6/26 Michaël Michaud <michael.mich...@free.fr > <mailto:michael.mich...@free.fr>> > > 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://sprint.com/first> -- > http://p.sf.net/sfu/sprint-com-first > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Jump-pilot-devel mailing list > > Jump-pilot-devel@lists.sourceforge.net > <mailto: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://sprint.com/first> -- > http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > Jump-pilot-devel mailing list > Jump-pilot-devel@lists.sourceforge.net > <mailto: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 > ------------------------------------------------------------------------------ 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
