In the Emlid Reach app there are two coordinate systems with ETRS:27700. Are they both exactly the same, or slightly different transformations? One is called OSBG1936 / British National grid, and the other OSGB36 / British National Grid. Is it slight differences in the vertical dautms. Any advice greatly appreciated. Thanks!
I haven’t had a chance to read all of this but I suspect the two grid systems you are referring to (they may be same-different abbreviations) have different ellipsoid designs, much like here in the US, the old NAD27 (and it’s various flavors) versus NAD83 and all it’s different ellipsoids. Fascinating read. You could also look at the ellipsoid parameters.
@EBE111057 thanks. That’s what I thought. But I’m currently confused as they can have the same EPSG code. In the list of UK coordinates systems there is only one 27700. Emlid shows two? None the wiser I’m afraid.
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Hi @excellent.geography ,
Welcome to our community forum,
They’re essentially the same—the only difference is in the technical implementation. One comes from the legacy registry, and the other from the new one. There are some slight differences while using the coordinate system of the legacy registry, i.e. it can’t be localized with the localization tool, and it’s not available for the Emlid Flow 360; only the new registry coordinate system is available.
Also, you’d notice the difference if you clicked on the info icon: the first one looks nice and clear, while the second is just plain text. So, it’s always best to go with the first one!
It’s worth mentioning that we’re currently transforming all the coordinate systems from legacy to the new registry, so in the future, there will be only the coordinate system of the new registry.
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