[Proj] MapInfo coordsys to proj.4 syntax
Paul Surgeon
surgpub at telkomsa.net
Tue Jun 6 04:04:56 EDT 2006
That helped a bit Anthony although it's not quite there yet.
I changed the false northing from 200000 to 2200000 because the MapInfo user
created their own coordsys definition and didn't use a stock NTF one. Using
the standard NTF false northing of 200000 shifts the data about 20 degrees
too far to the North.
I tried :
gdal_translate -a_srs "+proj=lcc +lon_0=2.337229166667 +lat_0=46.8
+lat_1=45.898918964419 +lat_2=47.696014502038 +x_0=600000 +y_0=2200000
+a=6378249.2 +rf=293.4660213 +towgs84=-168,-60,320,0,0,0,0 +units=m +no_defs"
temp1.tif temp2.tif
Now the raster data is only about 480 meters too far to the South and 48
meters too far to the East (rough estimate).
So something still isn't quite right.
Paul
On Tuesday 06 June 2006 02:00, Anthony Dunk wrote:
> Hi Paul,
>
> NTF uses a prime meridian of 2.337229166667 (Paris), not Greenwich.
>
> Below is the correct PROJ string for converting from Lat/Lon WGS84 to
> projected NTF (French Lambert II Centre).
>
> cs2cs +proj=latlong +a=6378137.0 +rf=298.257223563 +towgs84=0,0,0 +to
> +proj=lcc +lon_0=2.337229166667 +lat_0=46.8 +lat_1=45.898918964419
> +lat_2=47.696014502038 +x_0=600000 +y_0=200000 +a=6378249.2
> +rf=293.4660213 +towgs84=-168,-60,320,0,0,0,0 +units=m +no_defs
>
> Using this an input point of 2.33333E, 48.8667N is projected to
> 599766.90 mE, 429819.60 mN. This agrees with MapInfo's projection of
> the same point.
>
> Anthony.
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