Convert NAD_1983_Georgia_Statewide_Lambert to NAD83

Question

All I have a ESRI generated shapefile that uses: NAD_1983_Georgia_Statewide_Lambert

Here is the projection information:

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",656166.67],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",30.25],UNIT["Foot_US",0.3048006096012192]]

I believe the EPSG code is 102604

Can I use GDAL To re-project this to either a NAD83 or WGS84 projection? is there a better way to re-project this using a free tool? I'm having trouble verifying that ogr2ogr support this since it isn't a EPSG assigned range.

Answer 1

The WKT definition you give corresponds to this proj.4 definition:

+proj=lcc +lat_1=31.41666666666667 +lat_2=34.28333333333333 +lat_0=30.25 +lon_0=-83.5 +x_0=200000 +y_0=0 +datum=NAD83 +units=us-ft +no_defs

To proof it, put it into a text file and run gdalsrsinfo on it:

PROJCS["unnamed",
GEOGCS["NAD83",
    DATUM["North_American_Datum_1983",
        SPHEROID["GRS 1980",6378137,298.257222101,
            AUTHORITY["EPSG","7019"]],
        TOWGS84[0,0,0,0,0,0,0],
        AUTHORITY["EPSG","6269"]],
    PRIMEM["Greenwich",0,
        AUTHORITY["EPSG","8901"]],
    UNIT["degree",0.0174532925199433,
        AUTHORITY["EPSG","9108"]],
    AUTHORITY["EPSG","4269"]],
PROJECTION["Lambert_Conformal_Conic_2SP"],
PARAMETER["standard_parallel_1",31.41666666666667],
PARAMETER["standard_parallel_2",34.28333333333333],
PARAMETER["latitude_of_origin",30.25],
PARAMETER["central_meridian",-83.5],
PARAMETER["false_easting",656166.6666666667],
PARAMETER["false_northing",0],
UNIT["Foot_US",0.3048006096012192]]

Apart from some differences in the naming of the projection, note that the false easting is defined once in us-ft and once in meters.

There does not have to be a EPSG code for it, every map designer is free to choose the map parameters as he likes.

Usally, the transverse mercator CRS is used for the official state plane CRS in Georgia.

BTW you may find the projection inside https://github.com/ViceIce/DotSpatial/blob/master/DotSpatial.Projections/ProjectedCategories/StateSystems.cs and http://osgeo-org.1560.x6.nabble.com/Convert-X-and-Y-to-Lat-and-Lon-td3842165.html, but without the false Easting. You may find that also in this official document:

https://www.georgiaspatial.org/sites/default/files/GA_GIS_StdsGuidelines.pdf

---

You can put the proj.4 string into a text file named ge.prj, and reproject vector data with

ogr2ogr -s_srs ge.prj -t_srs epsg:4269 georgia-nad83.shp georgia-lambert.shp

Answer 2

I found the EPSG 102640 in the /bin/gdal-data/esri_extra.wkt file but it does not align with your projection. It is specified as:

102640,PROJCS["NAD_1983_StatePlane_Alaska_10_FIPS_5010_Feet",GEOGCS["GCS_North_American_1983",DATUM["North_American_Datum_1983",SPHEROID["GRS_1980",6378137,298.257222101]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["False_Easting",3280833.333333333],PARAMETER["False_Northing",0],PARAMETER["Central_Meridian",-176],PARAMETER["Standard_Parallel_1",51.83333333333334],PARAMETER["Standard_Parallel_2",53.83333333333334],PARAMETER["Latitude_Of_Origin",51],UNIT["Foot_US",0.30480060960121924],AUTHORITY["EPSG","102640"]]

I did not find a projection named as NAD_1983_Georgia_Statewide_Lambert.

In order to use OGR2OGR (GDAL is raster only) to reproject the data you would need to completely define your projection inline instead of by EPSG code. You can find some directions here:

http://www.gdal.org/ogr2ogr.html (says "Srs_def can be a full WKT definition (hard to escape properly), or a well known definition (ie. EPSG:4326) or a file with a WKT definition.")

http://www.gdal.org/classOGRSpatialReference.html#af1a29550373c2c14bd11514641e58e7c

Another option would be to add your projection to the esri_extra.wkt with a unique code (i.e. not 102640).