[Proj] cs2cs how to use

[Frank Warmerdam]

davidvaz wrote:
> Hello,
> 
> I'm new to proj and I need to convert some coordinates from wsg84 to tmerc.
> 
> The source coordinates comes from a gps device which uses wsg84 and I
> would like to convert them to:
> 
> PROJCS["Datum_73_Hayford_Gauss_IPCC",
>     GEOGCS["GCS_Datum_73",
>         DATUM["D_Datum_73",
>             SPHEROID["International_1924",6378388.0,297.0]],
>         PRIMEM["Greenwich",0.0],
>         UNIT["Degree",0.0174532925199433]],
>     PROJECTION["Transverse_Mercator"],
>     PARAMETER["False_Easting",180.598],
>     PARAMETER["False_Northing",-86.99],
>     PARAMETER["Central_Meridian",-8.131906111111112],
>     PARAMETER["Scale_Factor",1.0],
>     PARAMETER["Latitude_Of_Origin",39.66666666666666],
>     UNIT["Meter",1.0]]
> 
> This info was taken from a ESRI *.proj file and I believe that it
> contains all the information needed, but I haven't found the right way
> to use it.

David,

As Cliff mentions, the above does not include information on the datum
shift to be applied between WGS84 and "datum 73".  I believe the following
commandline would use the above parameters and Cliff's suggested datum
shift.

cs2cs +proj=wgs84 +datum=WGS84 +to \
       +proj=tmerc +k=1 +lon_0=-8.131906111111112 +lat_0=39d40 \
                     +x_0=180.598 +y_0=-86.66 \
                     +ellps=intl +towgs84=223.116,-106.825,-36.87

As Cliff mentions your false easting and northing seem pretty unusual.
It is also possible the signs on the towgs84 parameters need to be
changed.

Best regards,
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