[OSGeo Africa] Using south-orientated CRSs for GIS in South Africa

Thu Aug 29 08:55:48 PDT 2013

My apology for a late response for your invitation to attend as guest to the training workshop.
Unfortunately due to an extremely tight schedule with departure to German in the afternoon, I will not be able to attend.
Thanks again for the invitation

Ivan Farayi Muzondo
Head of Department, Geomatics
Faculty of Engineering and the Built Environment
Tel: (012) 382 5211/ 4918
Fax: (012) 382 5214
Bld 3:427
Email: Muzondoif at tut.ac.za<mailto:JanseVanRensburgZ at tut.ac.za>

[cid:image002.png at 01CDFFB8.B5AFB8F0]<https://www.facebook.com/TUTEngineeringFaculty> [cid:image003.png at 01CDFFB8.B5AFB8F0] <http://www.facebook.com/TUTengineeringnews>   [cid:image004.png at 01CDFFB8.B5AFB8F0] <http://twitter.com/TUTEngineering>   [cid:image004.png at 01CE18BD.8BD8A640] <http://www.tut.ac.za/Students/facultiesdepartments/ebe/Pages/default.aspx>
[cid:image006.png at 01CDFFB8.B5AFB8F0]
P Please consider your environmental responsibility before printing this e-mail or any other document

From: africa-bounces at lists.osgeo.org [mailto:africa-bounces at lists.osgeo.org] On Behalf Of Aslam Parker
Sent: 27 August 2013 12:47 PM
To: africa at lists.osgeo.org; newmarch at land-surveyors.com
Subject: Re: [OSGeo Africa] Using south-orientated CRSs for GIS in South Africa

Hi All

Can we please not call it the Lo system, it is the South African Coordinate Reference System. For a detailed and authoratative definition and explanation, please download
http://www.eepublishers.co.za/images/upload/positionit_2012/SA%20Coordinate%20reference%20system%20part1+2.pdf

Apparently ESRI has recently  implemented the south oriented SACRS in their software.

Aslam Parker | Director: Geo-spatial Information and Professional Support
|Chief Directorate: National Geo-spatial Information www.ngi.gov.za<http://www.ngi.gov.za/>| Cape Town|
Tel +27 21 658 4302| Fax +27 86 211 7919| Mobile 082 331 8501| aparker at ruraldevelopment.gov.za<mailto:aparker at ruraldevelopment.gov.za>

[cid:image007.png at 01CEA4E0.FB35A6F0]
P Please consider the environment before printing this email and/or any related attachments
>>> Peter Newmarch <newmarch at land-surveyors.com<mailto:newmarch at land-surveyors.com>> 8/27/2013 11:42 AM >>>
If one is producing maps in a country, then its common practice to use the national mapping system of that country. So I guess NGI does have a policy in the sense that their is a national mapping system for all data - which is the current Lo system.

Peter

Peter Newmarch

Professional Land Surveyor

4Y GeoInformatics Pty Ltd

Tel       : +27 31 5642856

Fax       : +27 31 5643074

Mobile    : +27 82 5705859

eMail     : newmarch at land-surveyors.com<mailto:newmarch at land-surveyors.com>
On 2013/08/27 11:18 AM, Frank Sokolic wrote:
ArcGIS 10+ and the soon-to-be-released QGIS 2.0 contain the (correct) south-orientated definitions of the Lo coordinate reference systems. However, the problem with this is that there is a HUGE amount of spatial data in SA and neighbouring countries that use a "north-facing" orientation. To convert all of this to the south-orientated system will have a massive impact on the GIS community both in terms of money and time. Can we afford this?

Does National Geo-spatial Information (NGI) have a policy on which CRS to use for GIS? They also supply spatial data using "north-orientated" coordinates so perhaps they have a policy somewhere that states:
- use south-orientated coordinates for survey data
- use north-orientated coordinates for GIS data?

Frank.

On 26/08/2013 22:03, Gavin Fleming wrote:

Very topical point Frank

Now that EPSG and proj4 have codes and implementations for the
south-facing LO/Hartebeesthoek94 system, it's all well and good except
as you say most GIS practitioners use north-facing, which we should not
call 'LO' at all. I wish EPSG had set up the north facing series instead.

If you get coordinates from a surveyor they are likely to be
south-facing, otherwise not, probably because GIS has not been able to
handle south-facing till recently?

In my early GIS days if we got south-facing data, we'd flip it to
north-facing manually before continuing.

There's a bit of a blocker in QGIS 1.9 at the moment where, if you
define a north-facing LO CRS (which I prefer to call something like
'SouthAfricaTM19' instead of 'LO19'), it forces '+axis=wsu' into the
definition, which makes it south-facing. I've filed a bug report [1]
about this, hoping it gets fixed before 2.0 is released.

I'm working in Lesotho now on parcel data which is in north facing TM
(on the Cape datum still), though survey data comes in south-facing. The
LO/Cape datum series is also in EPSG now, but also only as south-facing
:-(.

[1] http://hub.qgis.org/issues/8487

Gavin

On 26/08/2013 17:08, Frank Sokolic wrote:

Dear List,

As many of you know, the South African coordinate reference system is
defined as a south-orientated system, with Westings (Y) increasing
towards the south and Southings (X) increasing towards the West.
However, in a GIS context I've only ever seen SA CRSs (e.g. Lo19,
Lo31, etc) represented with x-coordinates increasing eastwards and
y-coordinates increasing northwards.

So, for example, the coordinates of the entrance to Durban harbour are
represented in Hartebeesthoek94/Lo31 as
Y = -5641.000
X = +3305647.886
but in practice in a GIS this point is represented as
X = +5641.000
Y = -3305647.886

My question is: are there any GIS practitioners in South Africa who
use the SA CRSs in the south-orientated sense?

Regards, Frank.

_______________________________________________
Africa mailing list
Africa at lists.osgeo.org<mailto:Africa at lists.osgeo.org>
http://lists.osgeo.org/mailman/listinfo/africa

_______________________________________________
Africa mailing list
Africa at lists.osgeo.org<mailto:Africa at lists.osgeo.org>
http://lists.osgeo.org/mailman/listinfo/africa

=== Email Disclaimer =================================================== “The information contained in this email is confidential and may contain proprietary information. It is meant solely for the intended recipient. Access to this email by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted in reliance on this, is prohibited and may be unlawful. No liability or responsibility is accepted if information or data is, for whatever reason corrupted or does not reach its intended recipient. No warranty is given that this email is free of viruses. The views expressed in this email are, unless otherwise stated, those of the author not those of Department of Rural Development and Land Reform or its management. Department of Rural Development and Land Reform reserves the right to monitor, intercept and block email addresses to its users or take any action in accordance with its email use policy”. ====================================================================

________________________________

----------------------------------------------------------------------------------
Tshwane University of Technology
----------------------------------------------------------------------------------
This email is sent and received in terms of the Electronic
Communications Policy of Tshwane University of Technology.
In line with this policy, this email is private, privileged and
confidential. The full text of the Electronic Mail Disclaimer
can be seen on the TUT web site at
http://www.tut.ac.za/Other/disclaimer/Pages/default.aspx
or obtained by phoning (012) 382-5911
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20130829/33a6c18f/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 825 bytes
Desc: image001.png
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20130829/33a6c18f/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.png
Type: image/png
Size: 1021 bytes
Desc: image002.png
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20130829/33a6c18f/attachment-0007.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.png
Type: image/png
Size: 750 bytes
Desc: image003.png
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20130829/33a6c18f/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image004.png
Type: image/png
Size: 1321 bytes
Desc: image004.png
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20130829/33a6c18f/attachment-0009.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image005.png
Type: image/png
Size: 29260 bytes
Desc: image005.png
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20130829/33a6c18f/attachment-0010.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image007.png
Type: image/png
Size: 18403 bytes
Desc: image007.png
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20130829/33a6c18f/attachment-0011.png>