[Proj] Help with a custom projection that is Transverse Mercator with Affine post-process

[James Cox]

Hi all,

I've subscribed in the hopes of tapping into a more specific group
than the general one on GIS Stack Exchange. I've also posted my
question there, I hope that's OK.

I am trying to define some of my local TMAF grids in PROJ.4 so I can
reproject points between the local grid and MGA95 and/or WGS84.

For these grids I have the MapInfo CoordSys clause which defines a lot
of parameters.
eg: “CoordSys Earth Projection”, 8, 33, 7, 117, 0, 0.9996, 500000,
10000000, 7, 0.890953, -0.455062, 2903977.24, 0.455063, 0.890954,
-6919253.68, -100000, -100000, 100000, 100000

>From the MapInfo doco I can see these parameters align to Datum,
Origin Latitude, Scale at Origin, False Easting/Northing, and the
Coefficients for the Affine Process.

What I'm having trouble with is trying to find out how to use these
coefficients when creating a new custom projection, and the parameters
in the PROJ.4 string that they could correctly map to.

Any help would be gratefully appreciated.

Cheers,
James