[Gdal-dev] Projection issues with OGR/Proj.4.

[Frank Warmerdam]

Sheykhet, Rostic wrote:
> Hi All,
> 
> I am trying to convert a shape using OGR calls from Lon/Lat to
> California VII State Plane Projection.  I get Easting and Northing out
> of it, but when I try to use other tools (ArcMap, OSSIM, Corpscon 6)
> they interpret these easting and northing values to be in a completely
> different place.  Here are the values:
> PROJ.4 coordinate system string:
> 	+proj=lcc +lat_2=34.41666666666666 +lat_1=33.86666666666667
> +lat_0=34.13333333333333 +lon_0=-118.3333333333333
> +x_0=1276106.450596901 +y_0=127079.524511049 +ellps=clrk66
> +datum=NAD27 +to_meter=0.3048006096012192 +no_defs
> 
> Original Lon/Lat:  -117.2038, 32.7161
> 
> OGR/Proj.4 Output: 4534220.33, -96890.84
> 
> Other Tools' idea of what easting/northing for this lon/lat should be:
> 4534487.622, 3647093.557
> 
> Other Tools' idea of where OGR/Proj.4-converted easting/northing values
> are: -117.324683175, 22.495186883.
> 
> Any suggestions are appreciated.

Rostic,

What WKT .prj file does ArcGIS use for the coordinate system?

I checked an old ArcGIS "26747.prj" and I see that it is using
a false northing of 4160926 feet while the OGR definition for
EPSG:26747 has a false northing of 127079 feet.  I'm not sure which
is right but the different might well account for the error.

Best regards,
-- 
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