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I have coordinate data from the 1944 British Army General Staff, Geographical Section (GSGS) Cyprus map which was cast on the Cassini projection, but was referenced to the Clarke 1880 ellipsoid where a = 6,378,249.145 m and 1/f = 293.465.

I gather from Clifford Mugnier's 2006 article that the latitude of origin should be (φo) = 35º 00’ 00”N and the central meridian (λo) = 33º 19’ 00”E, with a False Easting = 200 km, and a False Northing = 150 km.

I've added these data to the prj file for the Cassini-Soldner projection ("Cassini-Soldner Cyprus", 30, 1000, 7, 33.316667, 35.00000, 200000, 150000), which puts the points in roughly the right location, but their locations are distorted slightly, resulting in some sites appearing in the sea, etc.

Is there any way of getting the points in the exact right location? Have I forgotten to include some information?

Thanks

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1 Answer 1

One thing you are missing is the datum shift from the Clarke 1880 ellipsoid to the WGS84 reference we are now using.

Clifford Mugnier mentions Δ X = –104 m, Δ Y = –101 m, Δ Z = –140 m

for ED50 in Cyprus, so I would try that and look if the results are better than without.

If you have recognizable points, you can play with the parameters until it fits.

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