I have seen numerous questions of this nature and all suggest incorrect assignment of CRS along the way. I feel I have tried every combination of relevant CRS values but still cannot load two particular vector layers such that they line up. I must be missing a trick somewhere.
The two layers come from OS: AddressBase Plus and Mastermap Topography. Specifically, I am trying to align the Address dataset with the Topographic Area dataset.
I can load them into FME Data Inspector and the address points align with buildings, but load them into QGIS and they are a few metres out.
When I check the CRS in FME it is reported as EPSG:27700 for both datasets, although oddly the Coordinate System for the address is labelled EPSG:27700 whilst the Topographic Areas is labelled BritishNatGrid (comparing the WKT shows they are identical, though).
When I load these datasets into QGIS, without specifying the CRS, it sets it to 27700 for the Topographic Areas, but 4326 for the Addresses. I don't understand why.
I have tried every combination (I believe I have) of setting the project CRS to different values, assigning different values to each layer, and turning OTF on and off, but to no avail.
Most things I try put the addresses off the coast of West Africa (I presume at lat/lon 0, 0), and the Topographic Areas are nowhere to be seen. The only combination that puts them even vaguely in the same vicinity as each other is with Addresses 4326 and Topographic Areas 27700, but they remain misaligned by a few metres.
Can anyone suggest a straightforward process for loading these datasets into QGIS so that they align?
Here is the WKT from FME (which aligns correctly). It is the same for both files:
PROJCS["British National Grid (ORD SURV GB)", GEOGCS["OSGB 1936", DATUM["OSGB_1936", SPHEROID["Airy, 1830",6377563.396,299.3249612664953, AUTHORITY["EPSG","7001"]], AUTHORITY["EPSG","6277"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433], AUTHORITY["EPSG","4277"]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",49], PARAMETER["central_meridian",-2], PARAMETER["scale_factor",0.9996012717], PARAMETER["false_easting",400000], PARAMETER["false_northing",-100000], UNIT["METER",1], AUTHORITY["EPSG","27700"]]
The results from ogrinfo are:
Metadata: DESCRIPTION=Ordnance Survey (c) Crown Copyright. All rights reserved, 2016 and produced by GeoPlace
Layer name: Address Geometry: Point Feature Count: 41206 Extent: (-0.135610, 51.323120) - (-0.062560, 51.369150) Layer SRS WKT: GEOGCS["ETRS89", DATUM["European_Terrestrial_Reference_System_1989", SPHEROID["GRS 1980",6378137,298.257222101, AUTHORITY["EPSG","7019"]], TOWGS84[0,0,0,0,0,0,0], AUTHORITY["EPSG","6258"]], PRIMEM["Greenwich",0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9122"]], AUTHORITY["EPSG","4258"]]
Metadata: DESCRIPTION=Ordnance Survey, (c) Crown Copyright. All rights reserved, 2016-04-05
Layer name: TopographicArea Geometry: Polygon Feature Count: 99404 Extent: (529039.110000, 159261.400000) - (535629.000000, 165876.100000) Layer SRS WKT: PROJCS["OSGB 1936 / British National Grid", GEOGCS["OSGB 1936", DATUM["OSGB_1936", SPHEROID["Airy 1830",6377563.396,299.3249646, AUTHORITY["EPSG","7001"]], TOWGS84[446.448,-125.157,542.06,0.15,0.247,0.842,-20.489], AUTHORITY["EPSG","6277"]], PRIMEM["Greenwich",0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9122"]], AUTHORITY["EPSG","4277"]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",49], PARAMETER["central_meridian",-2], PARAMETER["scale_factor",0.9996012717], PARAMETER["false_easting",400000], PARAMETER["false_northing",-100000], UNIT["metre",1, AUTHORITY["EPSG","9001"]], AXIS["Easting",EAST], AXIS["Northing",NORTH], AUTHORITY["EPSG","27700"]]
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option. Specify the CRS as 27700 and create the new shapefile. See if this aligns better.