[gdal-dev] Missing +gamma parameter for RSO

[Hilmy Hashim]

The RSO projection method for Malaysia is now classified by
epsg-registry.org as Hotine Oblique Mercator (variant A) EPSG:9812. This
affects the following projections - EPSG:3168, EPSG:3375, EPSG:3376 among
others.

At the moment, I get the following outputs from epsg_tr.py:

epsg_tr.py -proj4 3618
# Kertau (RSO) / RSO Malaya (m)
<3168> +proj=omerc +lat_0=4 +lonc=102.25 +alpha=323.0257905 +k=0.99984
+x_0=804670.24 +y_0=0 +a=6377295.664 +b=6356094.667915204 +units=m +no_defs
 <>

epsg_tr.py -proj4 3375
<3375> +proj=omerc +lat_0=4 +lonc=102.25 +alpha=323.0257964666666 +k=0.99984
+x_0=804671 +y_0=0 +ellps=GRS80 +units=m +no_defs  <>

which are missing the +gamma parameter. This parameter (Rectified Grid
Angle) is already included in the share/proj/epsg database:

# Kertau (RSO) / RSO Malaya (m)
<3168> +proj=omerc +lat_0=4 +lonc=102.25 +alpha=323.0257905 +k=0.99984
+x_0=804670.24 +y_0=0 +gamma=323.1301023611111 +a=6377295.664
+b=6356094.667915204 +units=m +no_defs  <>

# GDM2000 / Peninsula RSO
<3375> +proj=omerc +lat_0=4 +lonc=102.25 +alpha=323.0257964666666 +k=0.99984
+x_0=804671 +y_0=0 +gamma=323.1301023611111 +ellps=GRS80 +units=m +no_defs
 <>

Can this parameter be added to these projections as it is being applied in
the latest proj4 omerc.c?

Thanks

*Hilmy*
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