[gdal-dev] WKT to proj.4 - I'm complete lost!

[Markus Neteler]

2009/9/10 "José Roberto Pereira Jr." <ze.sjrp at gmail.com>:
> Hi list!
>
> I'm a newbie in geoprocessing and I need to transform a WKT representation
> to a proj.4. I found a example using proj utility:
>
> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0
> +k=1.0 +units=m +nadgrids=@null +wktext +no_defs
>
> but I don't understand nothing about! Someone could tell me some resource or
> help me for translate the following WKT to proj.4?
>
> GEOGCS[
>        "GCS_South_American_1969",
>        DATUM[
>                "D_South_American_1969",
>                SPHEROID[
>                        "GRS_1967_Truncated",
>                        6378160.0,
>                        298.25
>                ]],
>                PRIMEM[
>                        "Greenwich",
>                        0.0
>                ],
>                UNIT[
>                        "Degree",
>                        0.0174532925199433
>                ]
> ]
>
> Thanks for tips!!

I have saved your definition to a file, removed all spaces and linebreaks
and then used the "testepsg" tool:

testepsg yourdef.txt
Validate Succeeds.
WKT[f] =
GEOGCS["GCS_South_American_1969",
    DATUM["D_South_American_1969",
        SPHEROID["GRS_1967_Truncated",6378160.0,298.25]],
    PRIMEM["Greenwich",0.0],
    UNIT["Degree",0.0174532925199433]]

Simplified WKT[f] =
GEOGCS["GCS_South_American_1969",
    DATUM["D_South_American_1969",
        SPHEROID["GRS_1967_Truncated",6378160.0,298.25]],
    PRIMEM["Greenwich",0.0],
    UNIT["Degree",0.0174532925199433]]

Old Style WKT[f] =
GEOGCS["GCS_South_American_1969",DATUM["D_South_American_1969",SPHEROID["GRS_1967_Truncated",6378160.0,298.25]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]
ESRI'ified WKT[f] =
GEOGCS["GCS_South_American_1969",
    DATUM["D_South_American_1969",
        SPHEROID["GRS_1967_Truncated",6378160.0,298.25]],
    PRIMEM["Greenwich",0.0],
    UNIT["Degree",0.017453292519943295]]

PROJ.4 rendering of [f] = +proj=longlat +ellps=aust_SA +no_defs

Hope this helps
Markus