Take the 2-minute tour ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

I am using a tool which uses proj4 lib to project maps.

I have a set of xy coordinates to be converted to latlongs with that tool. as I have the source projection string say

+proj=aea +datum=NAD83 +ellps=GRS80 +lon_0=-96d +lat_1=45d30 +lat_2=29d30 +lat_0=37d30 +x_0=000000 +y_0=00000

if I pass

+proj=longlat +datum=NAD83 +ellps=GRS80 +lon_0=-96d +lat_1=45d30 +lat_2=29d30 +lat_0=37d30 +x_0=000000 +y_0=00000

as the destination projection

Will it give me a LAT LONG from the x,y supplied?

I know there are ways to write code and do inverse projection to get latlong, but I wanted to bypass that and use x,y as the input to the tool I have and get latlong from it by just using the proj4 string.

share|improve this question
    
I ment "as the destination projection will it give me a LAT LONG from the x,y supplied" –  user1541 Dec 28 '10 at 15:22
    
Does the edit help make the question clearer? –  Brad Nesom Dec 28 '10 at 16:32

1 Answer 1

You don't need the "+lon_0=-96d +lat_1=45d30 +lat_2=29d30 +lat_0=37d30 +x_0=000000 +y_0=00000" in the proj=longlat since it's LonLat and not a projected system.

If both systems have the same datum and ellps you're fine, else you maybe need to provide the +towgs84 parameter with datum-transformation parameters.

share|improve this answer
    
I guess the tool that I have doesent take proj4 strings with just proj= defination in it, as its giving me error / unexpected termination. Is there any tools online that gives us a source projection to destination projection conversion (and we specify both the projection strings). ? –  user1541 Dec 30 '10 at 16:20

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.