Points of View: The functions of maps

Programme Outline

00.00 - 02.05 Introduction

• Landscapes in town and country are complex; maps help you make sense of them. The elusive map controller sets our central character, Julia, a series of tasks requiring map skills.

• Julia follows route directions, but they do not give her any real sense of where she is going, or the layout of the city.
• We usually see the world from eye level, so most of the time we are seeing our surroundings from about 1.5 - 2 metres above the ground.
• From the top of Exeter cathedral (44 metres above the ground) Julia can begin to see the layout of the land below. She can see a pattern of paths weaving their way across the green and into the streets beyond.

• From her vantage point on top of the cathedral Julia is working out a route to a tall department store across the city.
• Drawing your own map helps you to understand that a map's point of view is always from above. To follow the route it helps to orientate your map.

• A view from a tall building can help to plot a route across short distances, but if we wish to travel any further, a street map is essential.
• Like Julia's simple hand-drawn map, the 'A to Z' map shows a two-dimensional plan of the city, seen from above. It has an alphabetical index of street names, which helps her to identify exactly where she is, and where she needs to go.

• We can see the landscape below in much the same way as our eyes move over a map. The higher we go, the greater the area we can see, but in less and less detail. Individual trees become woods and forests, and buildings merge into one another to become street blocks.
• Rise higher still, to a height of 500 metres, and the ground below looks even more like a map. At this height we can see patterns of streets and railway lines, building groups and motorway intersections beginning to emerge.
• By carefully orientating the map we can spot exactly the same areas on Julia's 1:25,000 scale map of Exeter.

• From 2,000 kilometres out in space it is easier to see what our planet really looks like, and to understand the map maker's biggest problem: how to represent a round globe on a flat map.
• Imagine cutting open a football and trying to flatten it out. This is what a map has to do. It has to attempt the impossible, to represent a three-dimensional world in two dimensions.
• Several solutions are widely used. One is to use the Mercator projection; another is to use azimuthal projections; and a third is to use the Peters projection.
• The choice of projection depends on how you want to use the map.
• We are familiar with a map of the world which has the British Isles bang in the centre. If you lived in China your map of the world would have China in the centre. And if you live in Australia, you might choose to draw the world upside down, with south at the top and north at the bottom.

• A typical map of the world has a scale of one to 70 million. That means one centimetre on the map represents 70 million centimetres.
• As we head back down towards the United Kingdom, the map scales get larger. As we return to Exeter we come to the most common map scales.
• First is the Ordnance Survey's 1:50,000-scale map. Next is the 1:25,000-scale map. This is the map Julia has been using in the balloon. And finally, the 1:10,000-scale map. The scale of this map is large enough to include street names.