[Proj] Help with a custom projection that is Transverse Mercator with Affine post-process
Mikael Rittri
Mikael.Rittri at carmenta.com
Tue Jan 29 04:02:37 EST 2013
Hello James.
Just a partial answer, I am afraid:
I don't think you can add an affine post-processing to a Proj.4 CRS definition.
For your example, the interpretation of the MapInfo CoordSys clause should be
"CoordSys Earth Projection", // Just a name (probably the wrong one in this case)
8, // The projection type, in this case Transverse Mercator
33, // The geodetic datum, in this case GRS80 (treat it like WGS84)
7, // length unit, in this case meter
117, // central longitude
0, // central latitude
0.9996, // scale factor
500000, // false easting
10000000, // false northing
7, // length unit for affine transformation, also meters,
0.890953, -0.455062, 2903977.24, 0.455063, 0.890954, -6919253.68, // affine parameters A, B, C, D, E, F
-100000, -100000, 100000, 100000 // bounds
I think the basic CRS in this example can be expressed in Proj.4 as
+init=epsg:28350
which gives GDA94 / MGA zone 50, but I think you must implement the affine transformation yourself.
I got the information from http://www.sgsi.com/dnld/MapInfoPro_UserGuide_Current.pdf
but I didn't understand the meaning of the affine parameters.
And I think the 8 ought to have been 3008, maybe...
Best regards,
Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com
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