Dnk Posted August 30, 2009 Share Posted August 30, 2009 Theres actually 3 Norths http://www.ordnancesurvey.co.uk/oswebsite/aboutus/reports/misc/north.html Quote Link to comment Share on other sites More sharing options...
ivan Posted August 30, 2009 Share Posted August 30, 2009 Oh FFS Dnk, don't confuse him any further. Quote Link to comment Share on other sites More sharing options...
Dnk Posted August 30, 2009 Share Posted August 30, 2009 oh ffs dnk, don't confuse him any further. Quote Link to comment Share on other sites More sharing options...
snake Posted August 30, 2009 Share Posted August 30, 2009 buy a map and a compass and draw your own lines on it:idea: Quote Link to comment Share on other sites More sharing options...
Ewen Posted August 30, 2009 Share Posted August 30, 2009 Usually, when Britain is depicted on its own on a map, Newport is directly south of Dundee. But when Britain is shown on a map with parts of Europe, Edinburgh is directly north of Newport. Ive even seen a map where Inverness has moved so far east that it is directly north of Newport. Quote Link to comment Share on other sites More sharing options...
Blackie Posted August 30, 2009 Author Share Posted August 30, 2009 Usually, when Britain is depicted on its own on a map, Newport is directly south of Dundee. But when Britain is shown on a map with parts of Europe, Edinburgh is directly north of Newport. Ive even seen a map where Inverness has moved so far east that it is directly north of Newport. That clears that up Quote Link to comment Share on other sites More sharing options...
Hermit Posted August 30, 2009 Share Posted August 30, 2009 Does this help? The 'curvy' grid is on compass directions relative to true north, the square grid is what OS use for GB mapping... (From p35 of this doc: http://www.arrows.demon.co.uk/wgs84/50000026.pdf) [ATTACH]97738[/ATTACH] If you look at an OS map, it has info on it about the direction of true and magnetic Norths for each corner of the map... So yes, on OS maps there is an angular offset that varies depending on where you look... BUT it's just a result of the projection used in OS maps. You could use a different projection which keeps north 'up' over the whole map, but then distances would look distorted instead - Scotland would be wider, south coast narrower. (There's always a distortion when projecting the 3D world onto a 2D map, but you can choose between distorting angles or distances, or both). Quote Link to comment Share on other sites More sharing options...
Ewen Posted August 30, 2009 Share Posted August 30, 2009 Does this help? The 'curvy' grid is on compass directions relative to true north, the square grid is what OS use for GB mapping... (From p35 of this doc: http://www.arrows.demon.co.uk/wgs84/50000026.pdf) http://www.mkivsupra.net/vbb/attachment.php?attachmentid=97738&d=1251641032 [ATTACH]97738[/ATTACH] If you look at an OS map, it has info on it about the direction of true and magnetic Norths for each corner of the map... http://i258.photobucket.com/albums/hh247/jungle_re/dartmoor0001.jpg So yes, on OS maps there is an angular offset that varies depending on where you look... BUT it's just a result of the projection used in OS maps. You could use a different projection which keeps north 'up' over the whole map, but then distances would look distorted instead - Scotland would be wider, south coast narrower. (There's always a distortion when projecting the 3D world onto a 2D map, but you can choose between distorting angles or distances, or both). My post should make more sense now. Quote Link to comment Share on other sites More sharing options...
Blackie Posted August 31, 2009 Author Share Posted August 31, 2009 Does this help? The 'curvy' grid is on compass directions relative to true north, the square grid is what OS use for GB mapping... (From p35 of this doc: http://www.arrows.demon.co.uk/wgs84/50000026.pdf) http://www.mkivsupra.net/vbb/attachment.php?attachmentid=97738&d=1251641032 [ATTACH]97738[/ATTACH] If you look at an OS map, it has info on it about the direction of true and magnetic Norths for each corner of the map... http://i258.photobucket.com/albums/hh247/jungle_re/dartmoor0001.jpg So yes, on OS maps there is an angular offset that varies depending on where you look... BUT it's just a result of the projection used in OS maps. You could use a different projection which keeps north 'up' over the whole map, but then distances would look distorted instead - Scotland would be wider, south coast narrower. (There's always a distortion when projecting the 3D world onto a 2D map, but you can choose between distorting angles or distances, or both). Brilliant, cheers Quote Link to comment Share on other sites More sharing options...
MrRalphMan Posted August 31, 2009 Share Posted August 31, 2009 The best I could do.. which in fact is rubbish. Not really relevant, but what type of soil do you have? Quote Link to comment Share on other sites More sharing options...
Blackie Posted August 31, 2009 Author Share Posted August 31, 2009 The best I could do.. which in fact is rubbish. http://www.garwood-voigt.com/catalogues/H23941BritainMerian.jpg Not really relevant, but what type of soil do you have? http://www.soton.ac.uk/~imw/jpg/ukmap8.jpg oooh interesting, We are number 20, Millstone grit, Devon Quote Link to comment Share on other sites More sharing options...
MrRalphMan Posted August 31, 2009 Share Posted August 31, 2009 We're Lower Eocene, whatever the hell that is.. Quote Link to comment Share on other sites More sharing options...
Al Massey Posted August 31, 2009 Share Posted August 31, 2009 If you look at an OS map, it has info on it about the direction of true and magnetic Norths for each corner of the map... And grid north with the GMA for the year of the map. What is it you are trying to achieve or want it for? Quote Link to comment Share on other sites More sharing options...
Blackie Posted August 31, 2009 Author Share Posted August 31, 2009 We're Lower Eocene, whatever the hell that is.. Estuary mud by the looks of it? Quote Link to comment Share on other sites More sharing options...
Blackie Posted August 31, 2009 Author Share Posted August 31, 2009 And grid north with the GMA for the year of the map. What is it you are trying to achieve or want it for? My brother is trying to get an arial MAGNETIC north. He just aske for a map with dead north on it Quote Link to comment Share on other sites More sharing options...
Al Massey Posted August 31, 2009 Share Posted August 31, 2009 My brother is trying to get an arial MAGNETIC north. He just aske for a map with dead north on it That could be a problem as they dont make a map with dead north on it as it changes every year Quote Link to comment Share on other sites More sharing options...
Blackie Posted August 31, 2009 Author Share Posted August 31, 2009 So whats dead north from ilfracombe Devon this year? Quote Link to comment Share on other sites More sharing options...
Al Massey Posted August 31, 2009 Share Posted August 31, 2009 So whats dead north from Devon this year? Im not too sure, all the info you need will be on a map. You need the year of the map was produced The GMA of that year And the GMA in total Then do a bit of math to get either magnetic north or grid north as the two norths get further and further apart every year Quote Link to comment Share on other sites More sharing options...
Al Massey Posted August 31, 2009 Share Posted August 31, 2009 So whats dead north from ilfracombe Devon this year? How far north you want to go? Quote Link to comment Share on other sites More sharing options...
Hermit Posted August 31, 2009 Share Posted August 31, 2009 Im not too sure, all the info you need will be on a map. You need the year of the map was produced The GMA of that year And the GMA in total Then do a bit of math to get either magnetic north or grid north as the two norths get further and further apart every year Grid north is a confusing term - I'd say true north instead, in what you just said there. Grid north on a map is straight up the sheet - it could be the same as true north (often is on a world map) but is different on an OS (or UTM ) map. Quote Link to comment Share on other sites More sharing options...
Havard Posted August 31, 2009 Share Posted August 31, 2009 Well, this thread has developed into quite an education. There was me thinking it was a great way of initially taking the piss...... Interesting stuff, please continue..!! H. Quote Link to comment Share on other sites More sharing options...
Al Massey Posted August 31, 2009 Share Posted August 31, 2009 Grid north is a confusing term - I'd say true north instead, in what you just said there. Grid north on a map is straight up the sheet - it could be the same as true north (often is on a world map) but is different on an OS (or UTM ) map. grid north is never the same as true north. But to get a true north you would need to know grid and magnetic north and use the GMA Quote Link to comment Share on other sites More sharing options...
Hermit Posted August 31, 2009 Share Posted August 31, 2009 How far north you want to go? Good point, if he's wondering which bit of Wales he hits first, it's not going to make much difference! Quote Link to comment Share on other sites More sharing options...
Al Massey Posted August 31, 2009 Share Posted August 31, 2009 The white line is true north to within 5 deg using a latitude of -4.10 on military maps Give or take 1 deg Hope it helps If i had a btter pic or knew how far you want to go i can do it better Quote Link to comment Share on other sites More sharing options...
Hermit Posted August 31, 2009 Share Posted August 31, 2009 grid north is never the same as true north. Sorry, that's just not right It depends on the projection used for the map - they're the same for many rectangular maps of the world... Quote Link to comment Share on other sites More sharing options...
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