[OSGeo Africa] CRS in use in South Africa

Wed Jan 24 03:49:23 PST 2018

A diagram is internally consistent

A consolidated GIS will have polygons that are not necessarily consistent with its component diagrams in shape, orientation, scale or position.

I think the SG could always have plotted form the SR, therefore diagram ccordinates did not serve just that purpose.

We need both. The storage point is perhaps not that critical – but reliable and easy access is.

The SG however does not have the capacity to create a reliable consistent, constantly improving combined data set.

There are numerous philosophical challenges in consolidating historic and current data, so it would be great to have it, - but only if it’s “Right” and understood.

A shift or changing control points is easily accommodated when cords are on the diagram – without having to puzzle through and select from a SR to understand the impact.

These are just random considerations relating to your interesting thought – not a thought through argument for or against.

Lance

From: Africa [mailto:africa-bounces at lists.osgeo.org] On Behalf Of Peter Newmarch
Sent: 2018/01/24 01:20 PM
To: africa at lists.osgeo.org
Subject: Re: [OSGeo Africa] CRS in use in South Africa

I follow, but the same is achievable by capturing the data (bearing and distance), and positioning such in relation to the abutting properties that presumably already exist on the system. Coordinates just create slivers on the edges as the odds are the new diagram differs from the adjoining diagram coordinates. Just the other day I differed by 1,5m with somebody else – nothing wrong with the surveys, we just used different coordinates. Capturing the coordinates does not actually mean that is where the property actually is. One would think that the capture of the relationships of properties would be more valuable so that as coordinates change the data is still valid.

Peter Newmarch

From: Lebogang Modiba [mailto:inah.modiba at gmail.com]
Sent: Wednesday, January 24, 2018 1:11 PM
To: newmarch at land-surveyors.com<mailto:newmarch at land-surveyors.com>; africa at lists.osgeo.org<mailto:africa at lists.osgeo.org>
Subject: Re: [OSGeo Africa] CRS in use in South Africa

Hi Peter

I understand that CSG is the only custodian for cadastral data but at times due to backlog their data is not updated and that puts a lot of  pressure on us using the data and in meeting our deadlines.
We do report the missing data to their offices but at times it takes too long for them to update.

Thanks
Ms Lebogang

On 24 Jan 2018 13:05, "Peter Newmarch" <newmarch at land-surveyors.com<mailto:newmarch at land-surveyors.com>> wrote:
Lebogang,

This is just a thought – but surely under the SDI act, the SGO is the Base data custodian – I know there are problems with data, but if people are calculating it themselves – how does one ever expect to have the “base data” corrected. Is it not easier to force a situation where all data comes from one source, all missing data goes through one source, and all changes in data goes through one source. ??

Peter Newmarch
From: Lebogang Modiba [mailto:inah.modiba at gmail.com<mailto:inah.modiba at gmail.com>]
Sent: Wednesday, January 24, 2018 1:01 PM
To: newmarch at land-surveyors.com<mailto:newmarch at land-surveyors.com>; africa at lists.osgeo.org<mailto:africa at lists.osgeo.org>
Subject: Re: [OSGeo Africa] CRS in use in South Africa

Hi Peter

The coordinates on the sg diagrams and general plans helps us alot especially in cases where the CSG spatial data recived from CSG offices are incomplete or somwtimes incorrect.We use those coordinates to update and validate  the cadastral data.
There are times where you find that the whole township is missing from CSG spatial data and you require to work on that township urgently therefore waiting for CSG officials tonot update it for u  not being an option.We use those coordinates to plot that whole township ourselves either using auto cad or ArcGIS.

I would request that there be education in helping GIS personnels in converting those coordinates into decimal degress rather removing them.

Kind regards
Ms Lebogang Modiba

On 24 Jan 2018 12:50, "Peter Newmarch" <newmarch at land-surveyors.com<mailto:newmarch at land-surveyors.com>> wrote:
Dear all,

I am interested in peoples thoughts on the Coordinates on diagrams and general plans. For surveyors its simply duplicated work and plays no part in the registration of the diagram or general plan. From what I can see it was needed in an era of time to assist in plotting things by hand on paper. Land Surveyors don’t use coordinates in reconstructing properties and replacing beacons so they really serve no purpose on the diagram or general plan. The information is still in the survey records as a separate coordinate list so the SG can plot the property appropriately.

What are peoples thoughts about removing them and relying only on the SGO spatial data for such ?

Regards

Peter Newmarch

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        Lance Nel
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