[Qgis-user] Transformation using NTv2 grids

[Jukka Rahkonen]

Burgstaller Stefan <Burgstaller at ...> writes:

> 
> 
> 
> Hi,
>  
> is it already possible to reproject shape-files using NTv2 grids? I was
looking for appropriate plugins, help documents and already available tools
but I have not found anything. Since the federal states in Germany start
>  to convert their geospatial data from Gauss-Kruger to ETRS89 with NTv2
grids this topic becomes more and more urgent.

Hi,

Just had a try last week after getting a shift grid file "kkj_eureffin.ct2"
for Finnish Gauss-Kruger -> ETRS89. Usage is like this (I gave all the proj
parameters by hand so I knew that just they were used):

ogr2ogr -f "ESRI Shapefile" -s_srs "+proj=tmerc +lat_0=0 +lon_0=27 +k=1
+x_0=3500000 +y_0=0 +ellps=intl
+towgs84=-96.0617,-82.4278,-121.7535,4.80107,0.34543,-1.37646,1.4964
+units=m +nadgrids=.\kkj_eureffin.ct2" -t_srs "+proj=utm +zone=35
+ellps=GRS80 +units=m +towgs84=0,0,0,0 +no_defs"
accurate_conversion_to_epsg_3067.shp original_epsg_2393.shp 

Took 2 minutes with a laptop to convert 1.2 million simple polygons.

-Jukka Rahkonen-

 
> Greetings,
>  
> Stefan Burgstaller
>  
> 
> 
> 
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