Dirk-Lüder Kreie wrote: > have a look at the debugHelper.pl in [EMAIL PROTECTED] it will give you the > latlon center of the tile bbox and the latlon of the center of the tile.
Thanks, but I still don't get it and need some more hints. This is about finding the corners of a tile which is a discrete unit with discrete center points. The tahproject.pm computes the mercator tile height the way I do and Tileset.pm also uses 256 pixel tile image size. I am guessing that the osmarender export function deliver tile density for any centerpoint, so I probably need to reach to the guy producing the export code or looking at the code itself to know how to compute corner coordinates for this : any center, any size "tile". The exporter takes the geodetic center as a parameter, but I expect it to deliver a map evenly around the center of the projection. If not I don't see how I can find the corners. chuss Olav > Olav Kvittem schrieb: >> Hi, >> >> I wonder how I compute the coordinates of the corners of the images >> received from the web export function >> for an osmarender image. I specify geodetic center position(degrees), >> zoom level and image size and get at nice map image. >> The projection is of cource Mercator and I can linearly map mercator >> coordinates onto the image. >> But how do I know the coordinates of the corners of the returned image ? >> >> The url I use is : >> http://server.tah.openstreetmap.org/MapOf/index.php?long=10.17456&lat=56.01566&z=6&w=500&h=592&format=png' >> >> >> >> The tile-size for each level is 256x256 so given the zoom-level I could >> compute the pixel density from the >> world map size in mercator projection. >> That works for east direction which is linear, but for the northern >> direction the projection is nonlinear and >> I am not sure if the geodetic center that I specify is at the center of >> the returned image or not. > > have a look at the debugHelper.pl in [EMAIL PROTECTED] it will give you the > latlon center of the tile bbox and the latlon of the center of the tile. > > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
