[OSGeo Africa] Surveyor General Diagram - Mapping property boundary points

[S Coetzer]

Hi Wesly

Zoltan is correct, use Cape datum for 1975 data, I think the EPSG code is:
22279

In QGIS, use 22279 to filter your CRS and you'lle find it.

Good luck.

Sarel Coetzer

On Mon, Sep 29, 2014 at 2:37 PM, Dr Wesley Roberts <
wesley at biocarbonpartners.com> wrote:

> Dear Colleagues,
>
>
>
> A friend has asked me to produce a map using a title deed SG document. The
> property in question was surveyed in 1975 and it appears to make use of the
> LO19 coordinate system. I am not that familiar with LO19 and am having some
> trouble with defining a proj 4 projection in QGIS. I have produced a custom
> CRS based on the this post by Gavin Flemming (
> http://afrispatial.co.za/foss-gis/south-african-projections-in-foss-gis/).
> All seems well until I look at the location, I can find it using ancillary
> data. The coordinates on the title deed match only in the X domain (I have
> swopped both the X and the Y as well as the sign) while the Y domain
> appears to be “way out”. The SG title deed coordinate for one of the Y
> points is -9105.30 (Constant +9 760 000,00) while the same location in the
> QGIS returns a Y coordinate of around -3 769 758. Can anyone shed light on
> why there is such a large difference between the SG Diagram and the actual
> location?
>
>
>
> 1.       I am thinking that it might be something to do with the fact
> that the property was surveyed in 1975, any ideas?
>
> 2.       I have used the following proj 4 definition – have I missed
> something?
>
>
>
> +proj=tmerc +lat_0=0 +lon_0=19 +k=1 +x_0=0 +y_0=0 +ellps=WGS84
> +datum=WGS84 +units=m +no_defs
>
>
>
> Any help on this matter would be greatly appreciated.
>
>
>
> Regards,
>
> Wesley
>
>
>
> [image: Email_Signature]
>
> Wesley Roberts, PhD
>
> Geospatial Manager
>
> Biocarbon Partners
>
> wesley at biocarbonpartners.com
>
> Cell RSA: +27 83 5355 646
>
>
>
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