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enter image description hereI've imported UK wide coverage of ESC wind exposure data as a raster to ArcMap 10.2. The data is in WGS 1984 Pseudo Mercator which puts it way out against the UK OS standard grid. I can't get it to transform to OSGB1936 in ArcMap. In QGIS it seems to work fine and correlates with other UK vector data. Any suggestions?

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    Please edit the question to specify the exact steps you've used to deproject the Web Mercator to GCS_WGS_1984 and transform it to an Airy_1830 spheroid. – Vince Jul 1 '16 at 20:08
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You probably want the OSTN02 NTv2 grid file, which we just put into ArcGIS around version 10.4 or later. Download the file here:

https://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-net/ostn02-ntv2-format.html

In an Explorer window, browse to:

C:\Program Files\ArcGIS\Desktop10.1\pedata\ntv2

and create a new folder called uk.

Copy the OSTN02_NTv2.gsb file into the uk folder. After you restart/open a new ArcMap session, you should be able to use this transformations: OSGB_1936_To_WGS_1984_7.

(Transformation definition is already there, but the data was not being installed.)

  • Hi many thanks for the help. I've done as you suggest and the transformation as above appears as the best option in the transformation dropdown, I have used it, but it doesn't seem to change the projection. In terms off offset distance the ESC data is around 0.84km to the west & 21km to the north of the base OS data, not sure if this helps? – IJT Jul 4 '16 at 12:48

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