Re: OS Map refs.

[Richard Langley]

The use of grid squares for the U.K. National Grid was introduced to reduce
the number of digits required to give a reference. E.g., for a place with full
National Grid coordinates 538857.2345 metres easting, and 177345.3456
metres northing (a position given to the nearest 0.1 millimetres -- pushing
the limits of even GPS technology), the grid square designation to the
nearest metre is TQ 3885777345. Grid squares are  really only helpful for low
precision references. See  for
further explanation.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Tue, 10 Sep 2002, Ian Maddocks wrote:

>Hi Tony
>
>>Am I correct in thinking that:
>>OSX the 'Grid East Value' and
>>OSY the 'Grid North Value?   in this context?  O-)
>
>Yes - if you look on the OSGB map included in the BSS glassary
>http://www.sundialsoc.org.uk/glossary/ap11/ap11.htm
>the 0-700km eastings and 0-1300km northings are noted up the sides.
>
>I first found this form of grid reference used last year - at the end of the 
>Foot & Mouth crisis i downloaded a table of footpaths in the lake district 
>that were open , given as 12 figure references!
>for example those in NX grid square were 3EEEee5NNNnn.  ie what would 
>normally be NX EEENNN.   Yes with enough digits they were quoted to the 
>nearest meter!
>
>regards
>
>Ian Maddocks
>
>
>
>
>_
>Join the world?s largest e-mail service with MSN Hotmail. 
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>


=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 



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Re: OS Map refs.

[Ian Maddocks]

Am I correct in thinking that:
OSX the 'Grid East Value' and
OSY the 'Grid North Value?   in this context?  O-)


Yes - if you look on the OSGB map included in the BSS glassary
http://www.sundialsoc.org.uk/glossary/ap11/ap11.htm
the 0-700km eastings and 0-1300km northings are noted up the sides.

I first found this form of grid reference used last year - at the end of the 
Foot & Mouth crisis i downloaded a table of footpaths in the lake district 
that were open , given as 12 figure references!
for example those in NX grid square were 3EEEee5NNNnn.  ie what would 
normally be NX EEENNN.   Yes with enough digits they were quoted to the 
nearest meter!


regards

Ian Maddocks




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