[Proj] Fwd: proj4 definition for European Forest Map

[Jose Gonçalves]

Hello

The third definition is ok. Since you are specifying both semi-axis the
flattening is redundant. The first is wrong because +rf should be infinite
in the case of the sphere. Within PROJ syntax you could also use:

proj +proj=laea +lat_0=48 +lon_0=9 +x_0=0 +y_0=0 +R=6378388 +units=m
+no_defs

Regards

José A. Gonçalves



2010/6/24 Agustin Lobo <alobolistas at gmail.com>

> Hi!
>
> The European Forest Map has the following projection (according to a
> file distributed along with the file):
>
> Projection: Lambert_Azimuthal_Equal_Area
> Parameters:
>  False_Easting: 0.000000
>  False_Northing: 0.000000
>  Central_Meridian: 9.000000
>  Latitude_Of_Origin: 48.000000
> Linear Unit: Meter (1.000000)
> Coordinate system
> Geographic Coordinate System:
> Name: GCS_User_Defined
> Angular Unit: Degree (0.017453292519943299)
> Prime Meridian: Greenwich (0.000000000000000000)
> Datum: D_User_Defined
>  Spheroid: User_Defined_Spheroid
>  Semimajor Axis: 6378388.000000000000000000
>  Semiminor Axis: 6378388.000000000000000000
>  Inverse Flattening: 0.000000000000000000
>
> I've made several trials to set up a custom projection (in QGIS):
> 1.
> +proj=laea +lat_0=48 +lon_0=9 +x_0=0.000 +y_0=0.000 +a=6378388.0000
> +b=6378388.000 +rf=0.000 +units=m +no_defs
> Rejected by the custom projection tool as erroneous
>
> 2.
> +proj=laea +lat_0=48 +lon_0=9 +x_0=0.000 +y_0=0.000 +a=6378388.0000
> +b=6378388.000 +f=0.000 +units=m +no_defs
> Accepted by the custom projection tool but the Properties dialog does
> not accept it
>
> 3.
> +proj=laea +lat_0=48 +lon_0=9 +x_0=0.000 +y_0=0.000 +a=6378388.0000
> +b=6378388.000 +units=m +no_defs
> Seems to work fine.
>
> I'd like if someone could actually confirm that the third proj4
> definition is actually
> in accordance with the definition provided in the server and that I
> have reproduced at the beginning of this
> message. I'm not sure if option 1 and 2 are rejected because they are wrong
> or
> this is a QGIS problem (message sent to the QGIS list remains unanswered).
>
> I also would like answer if there is a document instructing how to
> translate PROJCS specifications
> into proj4 format.
>
> Thanks!
>
> Agus
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