[gdal-dev] Re: How to declare State Plane coordinates?

[Frank Warmerdam]

Paul Selormey wrote:
> Hello All,
> Is there any function similar to the SetStatePlane to implement the
> Japanese 19 coordinate systems? Or a guide to implement one?

Paul,

I am not familiar with this zone system; however, looking in the EPSG
tables I do see a 19 zone japanese system which I presume is the one you
are referring to. If you have the EPSG support files installed properly
with GDAL (the data files from gdal/data) you should be able to define
one of these coordinate systems like this:

OGRSpatialReference oSRS;

oSRS.importFromEPSG( 30160 + nZone );

Alternatively, it looks like you could hand define Zone I something like this:

OGRSpatialReference oSRS;

oSRS.SetTM( 53.5, -8.0, 1.000035, 200000.0, 250000.0 );
oSRS.SetGeogCS( "Tokyo", "Tokyo", "Bessel",
6377340.189, inverse_flattening );
oSRS.SetTOWGS84( 506, -122, 611 );

The inverse flattening would have to be computed from the semi-minor axis
which is 6356034.448. The formula is:
invserse_flattening = 1/f = 1 / (semimajor/semiminor - 1.0)

I hope this helps.

Best regards,

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