[OSGeo Africa] Kathu coordinate system

Frank Sokolic sokolic at worldonline.co.za
Fri Jan 31 00:26:29 PST 2014

Hi Hanlie,

If the survey was done in 1968 is it not possible that the units are in 
Cape feet? Not sure when surveyors switched to using metres. Are you 
able to post a scanned copy of the survey diagram?

Regards, Frank.

On 31/01/2014 09:58, Walter Smit wrote:
> OK, Gavin and I must have read the numbers too quickly...we were wrong.
> I have made some enquiries and apparently the mine surveyors in the area
> know of this system, but nobody is able to give its actual details. Waiting
> on some more replies from surveyors, who might have more details.
> Is it really necessary to convert the coordinates? Can you not rather "warp"
> the diagram itself to other known boundaries? I did this pretty successfully
> with diagrams from the 1830s using the georeferencing toolbar in "that other
> GIS package" and shapefiles of Farm Portions from the Surveyor General.
> -----Original Message-----
> From: africa-bounces at lists.osgeo.org [mailto:africa-bounces at lists.osgeo.org]
> On Behalf Of Walter Smit
> Sent: 30 January 2014 03:00 PM
> To: 'Africa local chapter discussions'
> Subject: Re: [OSGeo Africa] Kathu coordinate system
> I agree with Gavin...since it is from a surveyor and from pre-1999...
> -----Original Message-----
> From: africa-bounces at lists.osgeo.org [mailto:africa-bounces at lists.osgeo.org]
> On Behalf Of Gavin Fleming
> Sent: 30 January 2014 02:18 PM
> To: africa at lists.osgeo.org
> Subject: Re: [OSGeo Africa] Kathu coordinate system
> Looks like it's south-oriented transverse mercator with a central meridian
> of 23 and an offset of some nice round number > 3000000 on the SO x axis (or
> a local reference latitude) and it would likely be on the Cape datum. A bit
> of playing around these parameters will hopefully position it right.
> Does searching on the khathu system not turn up anything?
> On 30/01/2014 13:56, Hanlie Pretorius wrote:
>> Hi,
>> I a hand-drawn survey diagram that I need to reproduce in QGIS. The
>> area is in the Northen Cape, close to the 23° E longitude.
>> The diagram was done in 1968 and its coordinate system is specified as
>> 'Kathu System'. The y coordinates are given first, are all positive
>> and they range from about 23 000 to 49 000. The x coordinates are
>> given second and they range from +31 000 to -153 000.
>> Can anyone tell me what the specifications for this coordinate system
>> would be? I.e. the information I would need to create a WKT or proj4
>> specification for the CRS.
>> Thanks
>> Hanlie
>> _______________________________________________
>> Africa mailing list
>> Africa at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/africa
> --
> regards
> Gavin
> Gavin Fleming
> http://afrispatial.co.za
> t: 0218630660
> c: 0845965680
> f: 0866164820

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