Hi, just a quick note to let you know that proj4js can do lazy loading of crs definitions.
But I doubt that we will be using projections other than 900913 in the map viewers, because 900913 is our only option if we want to use Google layers (and OSM if we don't want to provide our own tileset). Regarding pyproj, I'm not sure if it can do 7 parameter transformations right. -Andreas. On Jul 9, 2010, at 22:12 , David Winslow wrote: > So, this afternoon I started looking into updating the map serialization code > (for getting maps out to the browser and loading them in the various GeoExt > viewers.) > > See http://projects.opengeo.org/CAPRA/ticket/566#comment:13 > > Since we record the center of a map in lat/lon but display the map in > Spherical Mercator, some reprojection is involved somewhere along the way. > We can do this on the JavaScript side, but as we branch out into more > projections later (see > http://code.google.com/p/geonode-roadmap/issues/detail?id=19&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary%20category) > we will probably want this to happen on the server side, to avoid the map > viewer having to load lots of arbitrary CRS definitions. (Can proj4js load > projection information lazily?) > > So, I dug a bit into loading GDAL's python bindings, only to find it doesn't > easy_install. That's kind of a pain. > > I guess we have a few options - > > 1) Fix GDAL's setup.py > 2) Update the build instructions to include installing gdal via a > platform-specific installer and forbid --no-site-packages. (We will have to > instruct people to install gdal themselves either way; it is not included in > the python package.) > 3) Keep passing the lat/lon coordinates and leave the reprojection up to > OpenLayers. > 4) Use pyproj instead (http://code.google.com/p/pyproj/) which does > easy_install properly. > > Probably, the right strategy is to start working on getting a patch into > GDAL, but use OpenLayers reprojection in the meantime while we're only using > Spherical Mercator and Lat/Lon anyway. > > Other opinions? > > -- > David Winslow > OpenGeo - http://opengeo.org/ -- Andreas Hocevar OpenGeo - http://opengeo.org/ Expert service straight from the developers.
