[Qgis-user] Custom CRS: from WKT to PROJ.4

[Andre Joost]

Am 15.02.2016 um 16:17 schrieb Jakob Petersen:
> I’m using QGIS to produce a .svg layer to be imported into Adobe
> Illustrator and added to an existing map project. Apparently, a EPSG
> projection was not used and the following WKT parameters have been provided:
>
>
> PROJCS["Orthographic, meter (Pakistan)",GEOGCS["WGS
> 84",DATUM["wgs_1984",SPHEROID["WGS
> 1984",6378137,298.257223563],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4326"]],PROJECTION["Orthographic"],PARAMETER["false_easting",0],PARAMETER["false_northing",0],PARAMETER["latitude_of_center",30.292],PARAMETER["longitude_of_center",69.178],UNIT["Meter",1,AUTHORITY["EPSG","9001"]]]
>
>
> To write the PROJ.4 for the QGIS customised CRS I have used the parameters
> (+proj +lat_0 +lon_0 +x_0 +y_0) listed in
> http://www.remotesensing.org/geotiff/proj_list/orthographic.html
>
> The projection comes close, but I wonder if more parameters can be used
> than the ones listed by remotesensing.org?
>

You can put the WKT into a text file and run gdalsrsinfo on that. It 
responds:

PROJ.4 : '+proj=ortho +lat_0=30.292 +lon_0=69.178 +x_0=0 +y_0=0 
+ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs '

Apart from the ellipsoid, you could use a sphere with a=b or R=6371000.

HTH,

André Joost