Andrea Aime a écrit : > I'm wondering if the chained CRS classes are designed > to handle override as well as extension.
Yes, this is just a matter of factories order in the chain. The "TMS override" - "EPSG" - "wkt extension" order suggested in your email should work. However in the particular case of "Tile Map Service" or WMS 1.0, it may be better to use the FORCE_LONGITUDE_FIRST_AXIS_ORDER hint instead. It is possible to have two "EPSG" - "wkt extension" chains, one this hint set and the other one without the hint (i.e. with the EPSG latitude,longitude axis order). Using the hint avoid the need for redefining all geographic CRS in a new "TMS override" factory. It also avoid the probable loose (if overriding with WKT) of additional EPSG informations like the valid area and the risk of missing some geographic CRS. > (to see why, look at > http://wiki.osgeo.org/index.php/Tile_Map_Service_Specification, > Spatial Referencing Systems section). How do we comment about this page? I have two comments: * The page said "The EPSG definition for 4326 says that the coordinate order is latitude, longitude and that the units are degrees, minutes, seconds." The part about units is wrong. EPSG:4326 do not mandate a particular units (some other EPSG code do, but not EPSG:4326). Quite the opposite, EPSG just said "UoM: deg" (and not "DMS" as it does for other CRS). * The page introduces a new authority name, "OSGEO", for additional codes (instead of extending the EPSG name space like ESRI does). All right, but if we introduce a new name space, why not use this name space for modified EPSG code? Lets keep "EPSG:4326" in its official EPSG meaning (latitude, longitude) and defines "OSGEO:4326" as "EPSG:4326" with (longitude,latitude) axis order. > Would it also be possible to have chains share some parts? > For example, I may want to use EPSG - "wkt extension" chain > for normal processing, and "TMS override" - EPSG - "wkt extension" > just for handling the tiled requests, and sharing the common part > so that I don't load two times the EPSG data provider. Yes, it work like that. Martin ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
