Monday, 16 May 2005

Little things mean a lot

The Bag of Bears criticises the writer of this letter in today's Herald. The letter will probably disappear shortly from the paper's stone-age website, but the key point is this:
The old BBC weather charts used a standard Grid projection. The new-style maps use a perspective view taken from above the island and well to the south. This results in massive geographical distortion, such that the image of England (actually 50,000 square miles) occupies a graphical area at least 10 times that of Scotland (30,000).
I certainly agree with the Bear when he says:
Scotland should spend rather more time praising initiatives,
but I can't help thinking that Dr Fiddes (the letter writer) has a point.

These oddly distorted maps are very widespread in the London-based media, both in print and on television, and are not confined to the weather. I've never noticed any maps in the US, France, Germany or Italy, for example, that show their countries distorted in this peculiar way.

I myself favour the retention of the UK with the constituent parts having equal legislative powers at the local level, but I fear that desirable outcome may be in jeopardy. The recent discovery by our English friends of asymmetrical devolution may well lead to Scotland having independence thrust upon it. But if Scots themselves choose independence it will be because many folk up here get upset by an accumulation of little niggles of which asymmetrical weather maps are but one example.

Of course, if the London media had used proper maps they might have spotted the importance of the West Lothian Question a good many years ago!


David Farrer said...

Comments made on previous template:

Wikipedia has a good article on various projections: 
Since it is futher from the equator, the 'normal' Mercator projection inflates the size of Scotland compared to England. With the new BBC map, Scotland is compressed in terms of pixels occupied on screen, but everyone can tell see the perspective as the camera moves around. The brain is quite good at making up for things futher away seeming smaller.

26 May 2005, 17:08:04 GMT+01:00
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Andy Wood
AFAIK, the only map that works universally for long-distance navigation is a globe. 
Indeed. In fact, it is mathematically provable that no 2D representation of the earth's surface can be undistorted everywhere.

23 May 2005, 10:25:25 GMT+01:00
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The Mercator projection gave ships a constant compass bearing that would get them to the destination, but it usually wasn't the ideal great circle route. The closer the great circle went to the poles, the worse it was, so if you want to navigate in the polar regions you use a polar projection. Away from the poles, Mercator works fine for trips spanning a few degrees of longitude, but for longer trips you will save miles by following a great circle instead of the Mercator straight line. The equal-area projections I've seen would all be terrible for navigation except in the center of the map. AFAIK, the only map that works universally for long-distance navigation is a globe.

21 May 2005, 22:47:21 GMT+01:00
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Andy Wood
I seem to remember that the main advantage of Mercator is that a line drawn between any two points will be straight - something to do with shipping or navigation anyway. 
I'm not sure what the advantage of the Mercator projection is, but that advantage is mathematically impossible: pick any two points on the globe that are separated by 180 degrees of longitude. The shortest path between them will pass through one of the poles, but a straight line drawn on the map won't.

17 May 2005, 10:22:44 GMT+01:00
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David Farrer said...

Stuart Dickson
The old BBC map was not Mercator, as far as I am aware. Mercator is a global projection which has rather gone out of fashion, and it was not used for representing countries, regions or continents. 
I seem to remember that the main advantage of Mercator is that a line drawn between any two points will be straight - something to do with shipping or navigation anyway. 
The Peter's projection, from the old DDR, was equal area, but grossly distorted shapes. It is not widely used. Other equal.area projections are much better. but again, that was a global projection. 
It is actually dead easy to find excellent projections - equal area and small distortions of shape - for land-masses as small as GB. Obviously the BBC did not want an excellent projection - for reasons they have thus far decided to keep to themselves.

17 May 2005, 07:25:31 GMT+01:00
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Neil Craig
I saw the letter & thought it yet another case of Scots whingeing. If we have to look for stuff like this to feel oppressed then we arn't. 92% of viewers are from south of the border & are naturally more interested in what the weather will be like in their home towns than in Peterhead. 
The Mercator projection is actually slightly biased towards us because we are further north. In this way we are all used to seeing maps in which France, Germany, Greenland etc are very considerably over represented compared to India.

16 May 2005, 23:50:59 GMT+01:00
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Stuart Dickson
Here's a good map:

16 May 2005, 22:26:36 GMT+01:00
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Stuart Dickson
There are in fact many different projections, not all "normal" maps distort proportions at the poles. Egalitarians may like the various equal-area projections, but like most things, it is horses for courses. 
I am afraid that in this case, as in most things, the BBC has picked the wrong nag.

16 May 2005, 20:20:17 GMT+01:00
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David Farrer
it's a surprise to learn that Shetland isn't actually as big as Africa 
It just seems like it when one walks across Unst in a gale!

16 May 2005, 12:34:15 GMT+01:00
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The Bagged Bear
Hmmm. It's a tricky one this. Maps are and always have been political, as much as being a navigational tool, and one can always find an argument for use of gnomic or mercator projections as much as any other form of illustrative representation of land mass. 
One of the reasons I see this as a non-issue (though I do take your point that it can certainly be taken the other way) is that within Scotland STV have used the 'odd' maps for a while now. To my (limited) knowledge there haven't been howls of protest from the Orkneys or Nairn, that their parts of God's land appear as if they are being viewed through the wrong end of a telescope. 
On that basis I would be keen to avoid stories in the National Press about Scots complaining about how their country is represented on a map. The Welsh have probably had more grounds to complain about maps recently! Complaining Scots in the national press just serve to reinforce an unmerited though unfortunately widely accepted stereotype. It also doesn't really help when the current advertising strap line is (I think) 'The worlds Best Small Country'.

16 May 2005, 12:34:13 GMT+01:00
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Mark Holland
"Normal" maps of course tend to make territory closer to the poles larger than they actually are relative to area towards the equator due to the curvature of the globe needing to be flattened out. Which is why it's a surprise to learn that Shetland isn't actually as big as Africa.

16 May 2005, 12:03:34 GMT+01:00