[Proj] looking for the right params for RSO

[Hermann Peifer]

On 27/08/2010 08:57, Christoph Dohmen wrote:
> Hi list,
>
> I'm searching for the right parameter set for RSO projected coordinates.
>
> Given a dedicated point from google earth with lat-long = 100.563743E 5.389524N
>
> Having a raster dataset with a projection set as the following:
>
> PROJCS["Kertau_RSO_Malaya_Meters",
>      GEOGCS["GCS_Kertau",
>          DATUM["D_Kertau",
>              SPHEROID["Everest_1830_Modified",6377304.063,300.8017]],
>          PRIMEM["Greenwich",0.0],
>          UNIT["Degree",0.0174532925199433]],
>      PROJECTION["Rectified_Skew_Orthomorphic_Natural_Origin"],
>      PARAMETER["False_Easting",804671.299775],
>      PARAMETER["False_Northing",0.0],
>      PARAMETER["Scale_Factor",0.99984],
>      PARAMETER["Azimuth",-36.97420943711801],
>      PARAMETER["Longitude_Of_Center",102.25],
>      PARAMETER["Latitude_Of_Center",4.0],
>      PARAMETER["XY_Plane_Rotation",-36.86989764584402],
>      UNIT["Meter",1.0]]
>
> Inside the dedicated point has the coordinates 286400m east 596700m north.
>
> Now I want to set up a translation first via proj directly and later on
> for a gdal-warp to transform the rasterdataset.
>
> I tried out the parameter:
>
> cs2cs +init=epsg:4326 +to +proj=omerc +a=6377304.063 +rf=300.8017 +lat_0=4.0 +lonc=102.25 +alpha=323.025790562881987 +gamma=323.13010235415598 +k_0=0.99984 +x_0=804671.299775
>
> but the result is 617824.69 153846.36
>

You are getting somewhat closer to the expected result with:

cs2cs -v +init=epsg:4326 +to +proj=omerc +a=6377304.063 +rf=300.8017 
+lat_0=4.0 +lonc=102.25 +alpha=323.025790562881987 +k_0=0.99984 
+x_0=804671.299775 +no_uoff +rot_conv

286289.13  596607.56 0.00

You might have to look for appropriate towgs84 parameter values.

Hermann