[OSGeo Africa] How to convert "New Namibia" projection to EPSG 4326 in QGIS

[Gavin Fleming]

Hi Calle

If all you want to do is project your layers to 4326 on the fly then you don’t need to re-project them by saving them - you can change your canvas CRS (in the project properties, bottom right corner) to 4326 - that’s all. 

For interest, the proj4 projection string equivalent of that prj file is 

+proj=tmerc +lat_0=0 +lon_0=17 +k=1 +x_0=600000 +y_0=10000000 +datum=WGS84 +units=m +no_defs

Under Settings->Custom CRS you can add a new CRS. Call it ‘New Namibian’ and paste the above in. Then you will be able to use It like any other CRS. It’s simply Transverse Mercator (just like SA’s ‘LO’ system) with some offsets.

Gavin

> On 05 Feb 2018, at 20:14, Zoltan <zoltans at geograph.co.za> wrote:
> 
> Hi Calle,
> As you have correctly noted, the .prj file tells QGIS how to interpret th embeded "bunch of numbers" [ie: coordinates] in the shapefile geometry.
> This means that you cannot simply edit the prj file - you actually have to change the bunch of numbers inside the shapefile to be latlong values that are in the correct place in Namibia.
> So:
> Simply open a "clean" QGIS, and note that the empty viewport is in EPSG:4326 (bottom right corner of QGIS window.
> Drag and drop your shapefile into the Layers Panel (note the bottom right CRS should change to your Shapefile CRS)
> right-click your shapefile name in the Layers Panel and choose Save As
> In the pop-up window, check that "Format" is set to ESRI Shapefile, Choose a Filename for your LatLong shapefile and change CRS to EPSG:4326 - and click OK
> Your saved shapefile will now have been reprojected to GCS on  WGS84.
> To be pedantic, close this QGIS and open a new QGIS, and drag/drop your saved shapefile into it.
> 
> HTH,  (no, not the chlorine product)
> Zoltan
> 
> On 2018-02-05 17:53, Calle Hedberg wrote:
>> Hi,
>>  
>> I’ve received two shapefiles from Namibia – originally from the National Statistics Agency, I think – which has the following .prj file:
>>  
>> PROJCS["New_Namibian",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
>> PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",600000.0],PARAMETER["False_Northing",10000000.0],PARAMETER["Central_Meridian",17.0],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]
>>  
>> When I open the file in QGIS and hover over the maps, the coordinates shown are clearly projected coordinates.
>>  
>> My problem is that I need the maps in EPSG 4326 (WGS-84, geographical coordinates) format, and I’ve been unable to do the conversion – changing the value under shapefile->Properties make the shapefile disappear.
>>  
>> So I’m doing something wrong – probably something really dumb – but I don’t know WHAT….
>>  
>> Anybody able to give me step-by-step instructions on how to re-project “New Namibian” back to standard EPSG 4326?
>>  
>> Regards
>> Calle
>> Cape Town
>> 
>> 
>> _______________________________________________
>> Africa mailing list
>> Africa at lists.osgeo.org <mailto:Africa at lists.osgeo.org>
>> You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa <https://lists.osgeo.org/mailman/listinfo/africa>
> -- 
> 
> =============================================
> Zoltan Szecsei GPrGISc 0031
> Geograph (Pty) Ltd.
> GIS and Photogrammetric Services
> 
> P.O. Box 7, Muizenberg 7950, South Africa.
> 
> Mobile: +27-83-6004028
> Fax:    +27-86-6115323     www.geograph.co.za <http://www.geograph.co.za/>
> ============================================= 
> _______________________________________________
> Africa mailing list
> Africa at lists.osgeo.org <mailto:Africa at lists.osgeo.org>
> You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa <https://lists.osgeo.org/mailman/listinfo/africa>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20180205/6f7548c9/attachment.html>