Brigit, Thank you so much for the response. I implemented a temporary workaround at the Java application layer. But, I'll definitely take a look at your idea
-Adam On Fri, Jun 13, 2014 at 8:24 AM, Birgit Laggner <[email protected]> wrote: > Hi Adam, > > perhaps you could solve the problem with this workaround: > > 1. Transform pt1 into geometry data type with srid 4326 (coordinates are > in degrees, now) > 2. Create a new point by shifting pt1 for # degrees in x-direction > 3. Create a linestring geometry by connecting pt1 and the new point > 4. Transform the linestring back into geography data type > 5. Calculate length of linestring in meters > 6. Use length in meters for definition of the ST_DWithin radius > > It's a little bit complicated and maybe you came up with a better idea in > the meantime... > > Regards, > > Birgit. > > > > Am 02.06.2014 20:58, schrieb Adam Wright: > > We have several tables with latitude and longitude columns (data type: > numeric) and I need to calculate whether a given lat/lon is within # > degrees of a point-radius ring. I came up with the function below. The user > supplied radius has to be in degrees (e.g. give me all records within 5 to > 25 degrees of this lat/lon pair). Sample query: select * from mytable > where > dist_check(mytable.latitude.mytable.longitude,35.6895,139.6917,5,25)=1. > > Any advice on solving the same problem using the geography data type > when the input radius is supplied in degrees? > > CREATE OR REPLACE FUNCTION dist_check(lat1 numeric, lon1 numeric, lat2 > numeric, lon2 numeric, innerradius numeric, outerradius numeric) > > pt1 geometry; > pt2 geometry; > BEGIN > pt1 := ST_MakePoint(lon1,lat1); > pt2 := ST_MakePoint (lon2,lat2); > IF ST_DWithin(pt1,pt2,outerRadius) AND NOT ST_DWithin(pt1,pt2,innerRadius) > THEN return 1; > ELSE > return 0; > END IF; > > Thanks! > > > _______________________________________________ > postgis-users mailing > [email protected]http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >
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