[Proj] Convert X and Y to Lat and Lon

[Hamish]

don_nell wrote:
> I'm very new to mapping and I'm trying to use cs2cs.exe
> from Proj4 to
> convert the X and Y values from an ESRI shape file (roads
> from the state of
> Georgia) into Lat and Lon coordinates.  However, I'm
> not sure what
> parameters I need  to accomplish this. 
> 
> I've gotten pretty close using the parameters below (plus
> or minus a city
> block), but I'm sure I could do better.
> 
> +proj=tmerc +units=us-ft +datum=NAD83 +lat_0=-1.77517
> +lon_0=-83.5 +k=0.9999
> +x_0=0.0 
> 
> The "+lat_0" parameter was derived by trial and error. 
> 
> Can anyone tell me the correct parameters to use to make
> this work? 
> 
> The contents of the associated .prj file are as follows. 
> 
> Thanks in advance. 
> 
> Don 
> 


PROJCS["NAD_1983_Georgia_Statewide_Lambert"
,GEOGCS["GCS_North_American_1983"
,DATUM["D_North_American_1983"
,SPHEROID["GRS_1980",6378137.0,298.257222101]]
,PRIMEM["Greenwich",0.0]
,UNIT["Degree",0.0174532925199433]]
,PROJECTION["Lambert_Conformal_Conic"]
,PARAMETER["False_Easting",0.0]
,PARAMETER["False_Northing",0.0]
,PARAMETER["Central_Meridian",-83.5]
,PARAMETER["Standard_Parallel_1",31.41666666666667]
,PARAMETER["Standard_Parallel_2",34.28333333333333]
,PARAMETER["Latitude_Of_Origin",0.0]
,UNIT["Foot_US",0.3048006096012192]]


try:

+proj=lcc
+datum=NAD83
+x_0=0.0
+y_0=0.0
+lon_0=-83.5
+lat_1=31.41666666666667
+lat_2=34.28333333333333
+lat_0=0.0
+units=us-ft


that is just by hand, I think there is some util which comes
with the gdal(?) source code for translating WKT to +proj4
syntax.

there is one South Georgia LCC in the EPSG file, but it's a
bit different.


Hamish