You are right, it was quite obvious. First of all, I made an error in my e-mail since I was actually using lon_0=10 and not 0. But my main problem was that proj was returning a wrong y-coordinate. The error is the same as I mentioned in my first e-mail. Using cs2cs instead gave me the correct coordinate, and those coordinates makes my map correct :-)
Thanks for all you help Ed! Espen On 22/01/2008, Ed McNierney <[EMAIL PROTECTED]> wrote: > Espen - > > Those EXTENT values look odd. Your projection's X-origin is still at 0 > degrees longitude. If your X coordinates are 10 degrees East, then the > projected coordinates (in meters) shouldn't be about 37,000. That would mean > you're about 37 km east of the prime meridian, and you're not. At 60 degrees > North latitude one degree of longitude is 55.8 km, so if you're 10 degrees > East you should have an X coordinate of about 558,000 meters (a little more, > since you're more than 10 degrees East). > > When I use PROJ or CS2CS to project your values I get exactly the same Y > values but very different X values: > > cs2cs +from +init=epsg:4326 +to +proj=eqc +lat_ts=60 +lon_0=0 +x_0=0 +y_0=0 > +ellps=WGS84 +datum=WGS84 +no_defs +units=m > 10.6661 59.9155 > 593672.41 6669762.95 0.00 > 10.6824 59.9213 > 594579.66 6670408.60 0.00 > > These X values seem reasonable for your projection. The command line you > give for PROJ shouldn't actually work as given - the quotes get in the way. > You should be using a command like the one above to CS2CS, or: > > proj +proj=eqc +lat_ts=60 +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 > +no_defs +units=m > > for the conversion. I'm a little puzzled as to how you're getting those > results. Could you try both the PROJ and CS2CS command lines above to > double-check, and report the version of PROJ you're using? There's probably > something obvious here but I'm not seeing it. > > - Ed > > Ed McNierney > Chief Mapmaker > Demand Media / TopoZone.com > 73 Princeton Street, Suite 305 > North Chelmsford, MA 01863 > [EMAIL PROTECTED] > Phone: +1 (978) 251-4242 > Fax: +1 (978) 251-1396 > > -----Original Message----- > From: UMN MapServer Users List [mailto:[EMAIL PROTECTED] On Behalf Of Espen > Isaksen > Sent: Tuesday, January 22, 2008 1:45 PM > To: [email protected] > Subject: [UMN_MAPSERVER-USERS] proj=eqc with change of latitute > > Hi! > > This question originates from this earlier thread: > > http://lists.umn.edu/cgi-bin/wa?A2=ind0801&L=mapserver-users&D=1&T=0&P=37923 > > But since I learned a lot during that thread and because the thread is > full of all kinds of questions now I would like to ask a very specific > question again in a new thread. > > I have also checked out the archives at this list and the PROJ list. I > have found one similar question on this list in 2005: > > http://lists.umn.edu/cgi-bin/wa?A2=ind0504&L=MAPSERVER-USERS&P=R75005 > > Here is my question: > > I have set up a mapfile with projection parameters like this: > > EXTENT 10.6661 59.9155 10.6824 59.9213 > PROJECTION > "init:epsg:4326" > END > > From this mapfile I get a map over an small area in Oslo, Norway(I > cannot publish the data since the data is not free) > > Then I change my map file to this: > > EXTENT 37074.96 6669762.95 37982.21 6670408.60 > PROJECTION > "+proj=eqc +lat_ts=60 +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 > +datum=WGS84 +no_defs +units=m" > END > > The extent is calculated by using PROJ like this: > proj "+proj=eqc +lat_ts=60 +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 > +datum=WGS84 +no_defs +units=m" < test.txt > > where test.txt consists of the geographic coordinates in my first map file. > > This mapfile creates a map about 18000 meters north of my first > mapfile. This is similar to the post from 2005. Longitude seems to be > correct. > > I do not understand why Mapserver does not create approximatly the > same map in both map files? Is it not possible to use PROJ to convert > coordinates like this? If I set lat_ts=0 I do of course get the same > map, but that is not the projection I would like to use. > > And if I cannot do it like this, how can I calculate the shift in the > y-coordinate(about 18000 meters in this example)? > > Kind regards, > Espen >
