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<br><div><div>On 29 Aug 2013, at 9:19 AM, Frank Sokolic <<a href="mailto:sokolic@worldonline.co.za">sokolic@worldonline.co.za</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi list users,<br><br>Here's a slightly tongue-in-cheek article discussing the south-orientated CRS we use in southern Africa:<br><a href="http://trac.osgeo.org/proj/wiki/TMSO">http://trac.osgeo.org/proj/wiki/TMSO</a><br><br>Frank.<br><br>On 28/08/2013 09:29, Aslam Parker wrote:<br><blockquote type="cite">Hi All<br>The SA coordinate system uses the Transverse Mercator Projection (which<br>is standard in all GIS software) and applied certain rules to it (such<br>as south orientation). There is no reason why you cannot set a project<br>up in SA system (south oriented) and import whatever vector projection<br>you like, be it UTM, standard TM, as long as you associate the correct<br>coordinate system with the imported data, everything should fall in the<br>correct space.<br><br><br> >>> Frank Sokolic <sokolic@worldonline.co.za> 8/27/2013 2:07 PM >>><br>Hi Aslam,<br><br>What is NGI's position on GIS data? When I've obtained GIS data from NGI<br>in the past it has always been supplied as north-oriented, and not in<br>the south-oriented SA CRS. Was this because in the past there weren't<br>any GIS packages that supported the south-oriented SACRS?<br><br>Now that GIS programs are starting to support the SACRS (e.g. QGIS 2.0,<br>ArcGIS) does this mean that NGI will start distributing GIS data in the<br>correct orientation?<br><br>Frank.<br><br><br>On 27/08/2013 12:46, Aslam Parker wrote:<br> > Hi All<br> > Can we please not call it the Lo system, it is the South African<br> > Coordinate Reference System. For a detailed and authoratative definition<br> > and explanation, please download<br> ><br>http://www.eepublishers.co.za/images/upload/positionit_2012/SA%20Coordinate%20reference%20system%20part1+2.pdf<br> > Apparently ESRI has recently implemented the south oriented SACRS in<br> > their software.<br> ><br> ><br> > Aslam Parker | Director: Geo-spatial Information and Professional Support<br> ><br> > |Chief Directorate: National Geo-spatial Information www.ngi.gov.za<br> > <http://www.ngi.gov.za/>|Cape Town|<br> ><br> > Tel +27 21 658 4302|Fax +27 86 211 7919| Mobile 082 331 8501|<br> > aparker@ruraldevelopment.gov.za<br><mailto:aparker@ruraldevelopment.gov.za>__<br> ><br> > __<br> ><br> > __<br> ><br> > PPlease consider the environment before printing this email and/or any<br> > related attachments//<br> ><br> > >>> Peter Newmarch <newmarch@land-surveyors.com> 8/27/2013 11:42 AM >>><br> > If one is producing maps in a country, then its common practice to use<br> > the national mapping system of that country. So I guess NGI does have a<br> > policy in the sense that their is a national mapping system for all data<br> > - which is the current Lo system.<br> ><br> > Peter<br> ><br> > Peter Newmarch<br> > Professional Land Surveyor<br> > 4Y GeoInformatics Pty Ltd<br> > Tel : +27 31 5642856<br> > Fax : +27 31 5643074<br> > Mobile : +27 82 5705859<br> > eMail :newmarch@land-surveyors.com<br> ><br> > On 2013/08/27 11:18 AM, Frank Sokolic wrote:<br> >> ArcGIS 10+ and the soon-to-be-released QGIS 2.0 contain the (correct)<br> >> south-orientated definitions of the Lo coordinate reference systems.<br> >> However, the problem with this is that there is a HUGE amount of<br> >> spatial data in SA and neighbouring countries that use a<br> >> "north-facing" orientation. To convert all of this to the<br> >> south-orientated system will have a massive impact on the GIS<br> >> community both in terms of money and time. Can we afford this?<br> >><br> >> Does National Geo-spatial Information (NGI) have a policy on which CRS<br> >> to use for GIS? They also supply spatial data using "north-orientated"<br> >> coordinates so perhaps they have a policy somewhere that states:<br> >> - use south-orientated coordinates for survey data<br> >> - use north-orientated coordinates for GIS data?<br> >><br> >> Frank.<br> >><br> >> On 26/08/2013 22:03, Gavin Fleming wrote:<br> >>> Very topical point Frank<br> >>><br> >>> Now that EPSG and proj4 have codes and implementations for the<br> >>> south-facing LO/Hartebeesthoek94 system, it's all well and good except<br> >>> as you say most GIS practitioners use north-facing, which we should not<br> >>> call 'LO' at all. I wish EPSG had set up the north facing series<br> >>> instead.<br> >>><br> >>> If you get coordinates from a surveyor they are likely to be<br> >>> south-facing, otherwise not, probably because GIS has not been able to<br> >>> handle south-facing till recently?<br> >>><br> >>> In my early GIS days if we got south-facing data, we'd flip it to<br> >>> north-facing manually before continuing.<br> >>><br> >>> There's a bit of a blocker in QGIS 1.9 at the moment where, if you<br> >>> define a north-facing LO CRS (which I prefer to call something like<br> >>> 'SouthAfricaTM19' instead of 'LO19'), it forces '+axis=wsu' into the<br> >>> definition, which makes it south-facing. I've filed a bug report [1]<br> >>> about this, hoping it gets fixed before 2.0 is released.<br> >>><br> >>> I'm working in Lesotho now on parcel data which is in north facing TM<br> >>> (on the Cape datum still), though survey data comes in<br>south-facing. The<br> >>> LO/Cape datum series is also in EPSG now, but also only as south-facing<br> >>> :-(.<br> >>><br> >>> [1] http://hub.qgis.org/issues/8487<br> >>><br> >>> Gavin<br> >>><br> >>> On 26/08/2013 17:08, Frank Sokolic wrote:<br> >>>> Dear List,<br> >>>><br> >>>> As many of you know, the South African coordinate reference system is<br> >>>> defined as a south-orientated system, with Westings (Y) increasing<br> >>>> towards the south and Southings (X) increasing towards the West.<br> >>>> However, in a GIS context I've only ever seen SA CRSs (e.g. Lo19,<br> >>>> Lo31, etc) represented with x-coordinates increasing eastwards and<br> >>>> y-coordinates increasing northwards.<br> >>>><br> >>>> So, for example, the coordinates of the entrance to Durban harbour are<br> >>>> represented in Hartebeesthoek94/Lo31 as<br> >>>> Y = -5641.000<br> >>>> X = +3305647.886<br> >>>> but in practice in a GIS this point is represented as<br> >>>> X = +5641.000<br> >>>> Y = -3305647.886<br> >>>><br> >>>> My question is: are there any GIS practitioners in South Africa who<br> >>>> use the SA CRSs in the south-orientated sense?<br> >>>><br> >>>> Regards, Frank.<br> >>>><br> >>>><br> >>>> _______________________________________________<br> >>>> Africa mailing list<br> >>>> Africa@lists.osgeo.org<br> >>>> http://lists.osgeo.org/mailman/listinfo/africa<br> >>><br> >>><br> >><br> >> _______________________________________________<br> >> Africa mailing list<br> >> Africa@lists.osgeo.org<br> >> http://lists.osgeo.org/mailman/listinfo/africa<br> >><br> ><br> ><br> > === Email Disclaimer ===================================================<br> > “The information contained in this email is confidential and may contain<br> > proprietary information. 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