[Qgis-user] Custom Projection for EPSG 27700 when opening shp and TAB files from other software

[Etienne Tourigny]

.prj files lack TOWGS84 WKT parameter and EPSG (AUTHORITY) codes

In gdal master this has been fixed recently (gdal master 2f135c1d) by
adding the config option GDAL_FIX_ESRI_WKT=TOWGS84
see http://www.gdal.org/ogr/classOGRSpatialReference.html#ad556dfdc04d9ec5f1714fc6b5e0eb6a6
and http://trac.osgeo.org/gdal/ticket/4345

However, this uses GDAL/OGR 'preferred' datums, which may not be the
same as the one in your TAB file

Also, that fix only messes with the TOWGS84 parameters and not the
AUTHORITY nodes (EPSG code), which is why your CRS lacks the EPSG
code.

cheers
Etienne

On Wed, Mar 14, 2012 at 1:00 PM, Zirneklitis <eko at lanet.lv> wrote:
> Datums are slightly different.
>
> James Stott wrote:
>>
>> ..
>> The definition of a layer in QGIS using OSGB 1936 / British National
>> Grid (27700) is:
>>
>> ..  +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 ..
>>
>> ..
>>
>> below which seems to match the EPSG 27700 definition but does not get
>> recognised as 27700:
>>
>> ..
>> .. +towgs84=446.448,-125.157,542.06,0.1502,0.247,0.8421,-20.4894 ..
>>
>> ..
>
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