That is kind of what I was thinking Andrea; right now there is some code that already coverts from the screen bounds into the data bounds; perhaps we could teach this code to be aware of the dwithin units and also convert the distance into the data space?
I cannot remember if this code is in the renderer or part of the datastore's themselves? Jody On 12/04/2010, at 9:13 PM, Andrea Aime wrote: > Jody Garnett ha scritto: >> I had not thought of that; I always figured that the datastore should >> handle this part (especially if the actual units are provided). If >> people are keen we could review the postgis code and make a utility >> method for the various datastore implementations to call? > > Very few data sources actually have the machinery to deal with > dwithin on geographic data. > PostGIS does only starting with version 1.5, Oracle does, > I guess probably DB2 does too, maybe SDE too. > That said, I have no idea if the SQL encoders actually pass > down the unit. > > To support shapefiles we'd have to add code to make the in > memory dwithin take care of the math necessary to compute > point to line distances on an ellipsoid (the code I was > referring to before) > > Cheers > Andrea > > > -- > Andrea Aime > OpenGeo - http://opengeo.org > Expert service straight from the developers. > _______________________________________________ > User-friendly Desktop Internet GIS (uDig) > http://udig.refractions.net > http://lists.refractions.net/mailman/listinfo/udig-devel _______________________________________________ User-friendly Desktop Internet GIS (uDig) http://udig.refractions.net http://lists.refractions.net/mailman/listinfo/udig-devel
