Ed, I really appreciate your quick responses. I have looked at the tutorial and used 'cs2cs' to get new extent values and used output projection as shown below
PROJECTION "init=epsg:2163" END but I am getting the following error - "loadMapInternal(): General error message. Given map extent is invalid." The coordinates that I am using represent a part of India. I am not sure if the parameters I passed to 'cs2cs' to calculate the new extent are valid for india. I have used the exact same parameters as mentioned on the website - cs2cs +proj=latlong +datum=WGS84 +to +proj=laea +ellps=clrk66 +lat_0=45 +lon_0=-100 Also I am not sure if I can use epsg code 2163 for india. I am supposed to find out the correct code by looking at the proj/nad/epsg file? There are so many entries for India and I am not sure which one to use. Thanks Ramesh On Thu, 23 Feb 2006 16:53:21 -0500, Ed McNierney <[EMAIL PROTECTED]> wrote: >Ramesh - > >MapServer will do all the reprojection for you. You do not need to >convert your source data. You simply specify the input projection >(lat/lon) for your input data and the output projection (LAEA) for the >map image. > >To get started, use the MapServer Tutorial at >http://mapserver.gis.umn.edu/docs/tutorial/tutorial - there's a section >there on getting started with projections in MapServer. > > - Ed > >Ed McNierney >President and Chief Mapmaker >TopoZone.com / Maps a la carte, Inc. >73 Princeton Street, Suite 305 >North Chelmsford, MA 01863 >[EMAIL PROTECTED] >(978) 251-4242 > >-----Original Message----- >From: Ramesh Karra [mailto:[EMAIL PROTECTED] >Sent: Thursday, February 23, 2006 4:49 PM >To: [email protected]; Ed McNierney >Subject: Re: How to determine the scale > >Thanks Ed, > >Thank you very much for the quick response. How do I convert my lat/long >to a different projection, say LAEA? When I do this conversion, all my >shape files need to be re-created with this new projection co-ordinates, >right? >I have searched on the web, but could not figure out a way to convert >lat/long to LAEA. I really appreciate any pointers related to this. > >Thanks >Krishna > >On Thu, 23 Feb 2006 15:38:50 -0500, Ed McNierney <[EMAIL PROTECTED]> >wrote: > >>Ramesh - >> >>If your output map image is in a "lat/long" projection - which yours >>seems to be, since the extents are in degrees - then you really cannot >>put a scale bar on the map. Distances are not constant across such a >>map, and depend on the latitude and the orientation of the line you're >>measuring. A one-degree North/South line is not the same length as a >>one-degree East/West line (except if you're near the equator). >> >>If you want to put a usable scalebar on your map, measured in meters or > >>miles, etc., you need to use a different output projection - one that >>is designed to provide such measurements. >> >> - Ed >> >>Ed McNierney >>President and Chief Mapmaker >>TopoZone.com / Maps a la carte, Inc. >>73 Princeton Street, Suite 305 >>North Chelmsford, MA 01863 >>[EMAIL PROTECTED] >>(978) 251-4242 >> >>-----Original Message----- >>From: UMN MapServer Users List [mailto:[EMAIL PROTECTED] >>On Behalf Of Ramesh Karra >>Sent: Thursday, February 23, 2006 3:26 PM >>To: [email protected] >>Subject: [UMN_MAPSERVER-USERS] How to determine the scale >> >>Hi, >> >>I have a map file with extent "74.3605 24.2590 79.5400 20.5070". I have > >>a layer(with data in a shape file) with very few points >> >>75.23478 23.40182 >>75.78261 21.90126 >>76.37162 22.90461 >>77.32890 20.88712 >> >>The mapserver shows these points correctly. But it does not have >>correct idea about the distance between the points. How do I indicate >>the mapserver that these are latitude and longitudes and the distances >>should be calculated correctly? Do I need to use scale? or some other >>projection? >> >>I really appreciate any help in this regard. >> >>Thanks, >>Ramesh
