[QGIS-ZA-user] Hartebeeshoek L027

[Gavin Fleming]

Hi Jordaan


> On 03 Jan 2021, at 17:42, Jordaan Fouche via qgis-za-user <qgis-za-user at lists.osgeo.org> wrote:
> 
> Dear All
>  
>  
> I am buy working on a project which is in  Hartebeeshoek L027 (EPSG 2052). It appears that all my data is transposed. 

2052 will plot like that, there is nothing wrong though! Use it for ‘LO27’ data and it will overlay your other data perfectly. If you want to flip it the ‘right’ way with north up, just choose any appropriate north-up CRS as your project CRS, like a custom or ESRI one as described in https://gist.github.com/gubuntu/6403425#sacrs-north-oriented-crs-on-hartebeesthoek94-or-wgs84-datum.

I saw you got 3395 (World Mercator) to work - yes it will draw things the right way around but it is not a good CRS for a local, large-scale project like you have. 

>  
> Some of the vector data that I am importing has been exported from Arc, others are photo mozaics from the NGI, and others are SGO data, however every datapoint has been transposed. I.e. what should be plotting SW is plotting NE, and what should be plotting NW is plotting SE.

They were only flipped because you had the project CRS set to 2052, there’s nothing actually wrong. 

>  
> Has anybody encountered this problem before. I have corrected some of the data by exporting the geometry through MMQIS, then multiply the coordinates by -1 and, re-import to a WGS84 project. Then the data plots in the right place. But it is an helluva work around and it should not be like that. Or am I doing something wrong?

You really don’t need to do all that. If you have ‘west-south-up’ coordinates, such as SA survey coords, then load them as is and define them as 2052 (in the case of ‘lo27’). They will then draw in the right place with all your other data and all calculations done on them will be correct. 

Gavin

PS: I’ve updated my gist on CRSs in southern Africa, see https://gist.github.com/gubuntu/6403425 

>  
> Jordaan
>  
> <image001.png>
> _______________________________________________
> qgis-za-user mailing list
> qgis-za-user at lists.osgeo.org <mailto:qgis-za-user at lists.osgeo.org>
> https://lists.osgeo.org/mailman/listinfo/qgis-za-user <https://lists.osgeo.org/mailman/listinfo/qgis-za-user>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-za-user/attachments/20210118/6a4ca539/attachment.html>