[Proj] Rectified Skew Orthomorphic...

[Oscar van Vlijmen]

> From: "Michael Childs"
> Date: Wed, 7 Feb 2007 17:06:41 -0600
> Subject: RE: [Proj] Rectified Skew Orthomorphic...

> Now that it seems I should be able to implement the Borneo/East Malaysia RSO
> with the 'omerc' projection, does anyone have the exact parameters required?

The official Malayan GDM2000 Technical Manual has test points.
<http://www.jupem.gov.my/GDM/pdf/TechMan_Pub.pdf>
They are a bit sloppy wrt the old projections MRT and BT68: the test figures
are OK, but the parameters are unclear or wrong. I've figured them out.
For the modern GDM2000 projections the data are OK.

Test point and my results:
// BRSO (East Malaya)
lat= "6 52 42.45022"; lon= "116 50 47.58835";
// GRS80
lat0=4; lonc=115;
alfac= "53 18 56.91582"; gamma=asin(0.8)*rd; // rd: from radians to degrees
k0=0.99984; x0=0; y0=0;
Result: x,y = 793704.63096, 762081.04678
Technical Manual gives: 793704.631, 762081.047