[Qgis-user] Raster VRT SRS syntax

[Even Rouault]

Zoltan,

Le mercredi 29 octobre 2014 13:21:51, Zoltan Szecsei a écrit :
> Hi,
> I'm running an older version of gdalbuildvrt that does not recognise the
> a_srs parameter, so I want to replace line 2 of the resulting VRT file
> with my own SRS entry.
> I have tried:
> 
>     <SRS>HBKNO27</SRS>

Yes, that will not work. The VRT driver uses the SetFromUserInput() API. See 
its doc for accepted syntax : 
http://www.gdal.org/classOGRSpatialReference.html#aec3c6a49533fe457ddc763d699ff8796

Based on the definition I found in http://hub.qgis.org/issues/8487.pdf, I have 
managed to make it work with

<SRS>+proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=0 +y_0=0 +axis=enu +ellps=WGS84 
+towgs84=0,0,0,0,0,0,0 +units=m +no_defs</SRS>

Perhaps the following can work too (untested) provided a 'ZANGI' file exists in 
the PROJ.4 resource directory that contains the 'epsg' file, grids, and other 
files.

<SRS>+init=ZANGI:ZANGI:HBKNO27</srs>

Even

> 
> and various other permutations with and without the 'ZANGI:' prefix.
> 
>  From the GDAL tutorial, I know the EPSG code syntax style is
> <SRS>EPSG:4326</SRS>
> 
> The CRS I need is  ZANGI:ZANGI:HBKNO27 or 'South African CRS: HBK_NO_27'
> 
> Can someone please guide me to the correct syntax.
> 
> TIA,
> Zoltan

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