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Andyd32
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Joined: Oct 26, 2004
Posts: 29
Location: United Kingdom
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 Posted: Thu Mar 10, 2005 9:34 pm Post subject: OSGB and BNG |
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I am wondering if anyone can answer a question regarding OSGB and BNG.
Are they the same or is there a subtle difference between them?
If I have OSGB coordinates of 548133, 162990 what will they be in BNG?
I ask because I have quoted the coordinates above from a package which uses OSGB, but a third party is telling me that these are wrong as they use BNG coordinates and they think that 548077,163017 are the correct coordinates (BNG). I have 'Googled' the internet, but can find no way of cross referencing the two.
Any help greatly appreciated. |
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lbendlin
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Joined: 02/11/2002 22:41:59
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Location: Massachusetts, USA
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| Posted: Thu Mar 10, 2005 10:07 pm Post subject: |
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BNG is the same as OSGB
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barryd
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Joined: Mar 27, 2004
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Location: Cheshire, England
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| Posted: Thu Mar 10, 2005 10:22 pm Post subject: |
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Unless there's a surveyor about who can shed more light on this, I think you're right. This is based on what I've seen used and what I've learnt from the OS web sites.
The glossary on www.ordnancesurvey.co.uk has this:
| Quote: | National Grid
A metric grid based on the Tranverse Mercator Projection developed by Ordnance Survey in 1936 for use in Great Britain. Referred to in GIS by the code "OSGB36®" it is the de facto standard projection for display of UK based mapping. |
There's also a PDF called "OS Guide to Co-ordinate Systems" available on one of their websites, which goes into a lot more detail.
The only distinction I know about are the two ways to write a reference, i.e. the way you've written it, or the more common leisure format of using a two-letter code to indicate the 100km square, then giving the easting and northing within it, which for yours would become TQ 48133 62990, or more typically the less precise TQ 481 630.
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Baldlygo
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Joined: Jun 15, 2004
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Location: Shropshire(UK) - Welsh Border
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| Posted: Fri Mar 11, 2005 10:34 am Post subject: |
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This English Heritage pdf explains why you might find different bearings for the same place.
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Oldie
Pocket GPS Moderator
Joined: 22/11/2002 13:33:48
Posts: 992
Location: Surrey, UK
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| Posted: Fri Mar 11, 2005 12:11 pm Post subject: Re: OSGB and BNG |
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| Andyd32 wrote: | I am wondering if anyone can answer a question regarding OSGB and BNG.
Are they the same or is there a subtle difference between them?
If I have OSGB coordinates of 548133, 162990 what will they be in BNG?
I ask because I have quoted the coordinates above from a package which uses OSGB, but a third party is telling me that these are wrong as they use BNG coordinates and they think that 548077,163017 are the correct coordinates (BNG). I have 'Googled' the internet, but can find no way of cross referencing the two.
Any help greatly appreciated. |
The 6 digit numbers that you quote are Eastings and Northings. An OSGB Reference replaces the first digit of each group by a letter code (51 = TQ). So your other software might accept TQ 48133 62990.
Richard
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barryhunter
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Joined: Feb 18, 2005
Posts: 6
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| Posted: Wed Mar 16, 2005 2:46 pm Post subject: |
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OSGB (or more correctly OSGB36) and BNG (British National Grid) are one and the same.
As pointed out there are two main formats to write the same thing.
Eastings/Northings which is meters from a False origin off the Isles of Scilly
Later on the OS realised that a lot of the time the locations you working with where using the same 'grid square' - the first digit of the easting and northing. So looked for a way to make it easy to drop that part of the location to give 481 630. So adopting the then Secret Grid Letters used by the milerty during the war, they came up with the Grid Reference using a two letter Prefix. Thus if working with a small area (such as on a OS Landranger Map) you could quite easily just quote the numbers and still have a unique location (it actully repeats every 100km). If want a nationally unique location just add the letters. |
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