[geotk] Re: Gaus Conform Projection

[Martin Desruisseaux]

theuns a écrit :
> On the map they give the projection as:
> Gauss Conform Projection, Central Meridian 23° East, Hartebeesthoek 94
> Datum(WGS84 Spheriod)
> 
> Is this what you meant by using the Universal Transverse Mercator?

Apparently not. "Gauss-Kruger" and "Gauss-Boaga" are synonymous of UTM, but 
according the page below "Gauss Conform" is really a different beast:

     http://www.dwaf.gov.za/iwqs/gauss/node4.html

www.epsg-registry.org is down right now so I can not check the details of that 
projection, but I don't think that "Gauss Conform" is implemented in Geotk.


> And that this would preserve area for the specific region around 23°
> East?

I don't know for "Gauss Conform". But for the Mercator projections, they do not 
preserve area. They preserve angles instead. But if you don't move far away from 
23°, the simple Mercator projection may be an acceptable approximation.

They were some guidline about how to setup a "personal" Mercator projection with 
the "latitude true scale" of your choice here:

http://lists.osgeo.org/pipermail/geotoolkit/2009-September/000160.html

I need to reformat that content in a "how to" guide, but in the main time 
hopefully the above may be of some help?

	Martin