Hi Dane, thank you very much for your response to my question! And indeed the patch submitted by Frederik Ramm (btw: great guy, his book about openstreetmap is brilliant!) solved the issue. It is now possible to render the data using the UTM projection!
Thanks a lot, you saved my day :-) Dane Springmeyer wrote: > > My first guess would be that Mapnik is unable to reproject the osm data > into UTM because the osm layers extents are not valid for UTM. > > If this is the case, then this is partly a bug in Mapnik and party a > condition of trying to project global data into a local projection. See > the thread linked off of http://trac.mapnik.org/ticket/549 for more > details. > > Short of trying to apply that patch you could try setting the 'extent' > parameter for all your osm layers in the osm stylesheet to: > > '11.03,49.42,11.13,49.48' > > Let me know if that helps. If not let me know what osm extract you used > and I can try to test locally. > > Dane > > > On Jun 2, 2010, at 1:24 AM, kfr wrote: > >> >> Hello everybody! >> >> I'm trying to render some maps of the same area using different >> projections >> in order to compare the rendered images with each other. I.e. i defined >> an >> area and rendered the data from that area using e.g. UTM zone XY >> projection, >> google projection, and so on... In order to get the job easily done i >> wrote >> this little python script: >> >> (Note: my system is Ubuntu 10.04 as explained here >> http://weait.com/content/build-your-own-openstreetmap-server >> http://weait.com/content/build-your-own-openstreetmap-server , the >> projection definitions come from http://www.spatialreference.org/ >> http://www.spatialreference.org/ ) >> >> >> #!/usr/bin/python >> import mapnik >> >> mapfile = "osm.xml" >> >> projections = { >> "latlon": "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs", # >> EPSG:4326 >> "utm_32n": "+proj=utm +zone=32 +ellps=WGS84 +datum=WGS84 +units=m >> +no_defs", # EPSG:32632, >> "google": "+proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137 >> +b=6378137 +units=m +no_defs", # SR-ORG:95 >> "mercator_world": "+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +ellps=WGS84 >> +datum=WGS84 +units=m +no_defs", # SR-ORG:16 >> } >> >> ll = (11.03, 49.42, 11.13, 49.48) >> >> imgx = 1000 >> imgy = 1000 >> >> # Render an image for every projection >> for projName, projDef in sorted(projections.items()): >> >> print "Projection: " + projName >> >> # Load the map data >> m = mapnik.Map(imgx, imgy) >> mapnik.load_map(m, mapfile) >> >> # Override projection defined in osm.xml >> m.srs = projDef >> >> # Calculate projected boundaries >> prj = mapnik.Projection(projDef) >> c0 = prj.forward(mapnik.Coord(ll[0], ll[1])) >> c1 = prj.forward(mapnik.Coord(ll[2], ll[3])) >> >> # Apply bounding box >> bbox = mapnik.Envelope(c0.x, c0.y, c1.x, c1.y) >> m.zoom_to_box(bbox) >> >> # Render image >> im = mapnik.Image(imgx, imgy) >> mapnik.render(m, im) >> view = im.view(0, 0, imgx, imgy) >> view.save(projName + ".png", "png256") >> >> >> But here comes my problem: the UTM projection (called 'utm_32n' in the >> script) doesn't render the image i expected! Instead i only get a >> ocean-blue >> image. All the other projections work fine! This is quite annoying and >> frustrating, as the UTM projection is the most important one for my >> project. >> >> I googled through the whole internet and counldn't find any clue why the >> UTM >> projection won't work while all the others do... >> >> So if anyone can give me a hint i would be very thankful!! Perhaps i >> misunderstood som facts, have missed something, etc.... >> >> I uploaded the resulting images for all four projections: >> >> longlat projection: >> http://old.nabble.com/file/p28751475/latlon.png >> >> google projection: >> http://old.nabble.com/file/p28751475/google.png >> >> mercator projection: >> http://old.nabble.com/file/p28751475/mercatorworld.png >> >> utm projection: >> http://old.nabble.com/file/p28751475/utm32n.png >> >> Greetings from Germany... >> -- >> View this message in context: >> http://old.nabble.com/Problems-with-some-Mapnik-projections-tp28751475p28751475.html >> Sent from the Mapnik - Users mailing list archive at Nabble.com. >> >> _______________________________________________ >> Mapnik-users mailing list >> [email protected] >> https://lists.berlios.de/mailman/listinfo/mapnik-users > > _______________________________________________ > Mapnik-users mailing list > [email protected] > https://lists.berlios.de/mailman/listinfo/mapnik-users > > -- View this message in context: http://old.nabble.com/Problems-with-some-Mapnik-projections-tp28751475p28777331.html Sent from the Mapnik - Users mailing list archive at Nabble.com. _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
