[MS4W-Users] Coordinate Projects

Frank Warmerdam warmerdam at pobox.com
Wed Nov 11 14:01:26 EST 2009

Jeff McKenna wrote:
> 	"proj=utm"
> 	"zone=44"
> 	"a=6377276.345"
> 	"b=6356075.41314024"
>          "lat_0=7.000472"
>          "lon_0=80.771713"
>          "k_0=0.999924"
>          "x_0=200000"
>          "y_0=200000"
>          "rf=300"
> 	"units=m"
> 	"no_defs"

Jeff has some excellent suggestions, but I must clarify that you
should not mix proj=utm with specific settings of lat_0 and lon_0.
When your lat_0 and lon_0 are not the default for a given utm zone
you should instead just use proj=tmerc and specify all the parameters.

Honestly, I was suprised to see "utm zone 44" when the parameters
are so *not* UTM 44.  The lat_0, lon_0, x_0, y_0 and k values are all
different than UTM 44.

> I am not sure of how to specify the "Inverse Flattening" value, so I 
> have guessed that it is the "rf" parameter, but I am not sure. 

Yes, I believe +rf= is the right parameter, but the ellipse is also fully
specified with +a and +b (semi-major and semi-minor) axes.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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