We would be lost without maps!

Start here for several do-it-yourself excursions into the technology of map making....

This site explains how you can make maps yourself... the same way explorers and professionals do it.

Following these links to sub-pages, you will find an introduction.

A simple hypothetical example. (There are further theoretical points covered here, too.)
A real example.
Information about the main tool of the trade.
News of data sharing initiatives.
An account of making a map of Paris from some panoramic photos.

You can make simple maps (not too accurately!) with very little trouble or expense. You can make better maps if you have enough imagination and craftsmanship... and still without much expense. One excursion on the theme explores some general principles involved in making measuring instruments for any scientific enterprise. Even if you don't want to make a map, you could have fun thinking about how you would make one of the map-maker's tools.

The way explored here is based on taking bearings. Before I go any further, let me mention that no effort is made in any of this to measure elevations. The world is assumed to be flat, sorry.

The basic method......

You need two places in the area to be mapped, lets call them 'A' and 'B'. You need to be able to get to both. You must be able to see A from B and B from A. This can be as simple as a school playground. 'A' could be an isolated tree, 'B' could be the Centrex of a gate into the playground. The map-maker goes to 'A'. He/ she points one arm at 'B', and the other arm at something to be put on the map, let's say the door into the school building. We'll call it... guess what... 'C'. He notes the angle made by his arms while pointing to 'B' and the door. The correct, usual, obvious- once- you- understand- it name for this is: 'angle BAC'. (Or, you could call it 'CAB'... but that's the only other valid name. The letter 'A' must be in the middle because that is where the map-maker was standing pointing his arms, thus making the angle we have just named.)

Now the map-maker goes to 'B'. He points one arm at 'A', and, again, the other arm at the door into the school building. He again notes the angle made by his arms while pointing to the two places. This is angle ABC.

In the real world, many more angles would be involved, but these will do for now.

The map-maker then goes to a desk and gets out a piece of paper. He puts two dots on it (almost anywhere... put them in the 'wrong' places, and you'll soon see what limitations prevail.) He marks one A and the other B. He now draws a line from B to A. He then draws another line, going away from A. He draws it in the one place which makes an angle the same size as the angle his arms made when he stood at A and pointed to B and C. (The gate and the door). (Actually, there are two lines he can draw... but don't worry too much about that or you'll end up confusing yourself. If the map doesn't work, the map-maker needs to look for the 'other' angle BAC- that may be the problem.) This line can go from A to the edge of the page... as more angles are done, ways to economize on the length of line will become obvious. The map-maker must try to think about what he is doing as he goes along, to 'see' in his mind's eye the relationship between what is being drawn on the paper and what exists in the real world.

Next, the map-maker draws a line to complete the map's representation of angle ABC. The line from A to B is already drawn. A line is drawn away from B along in the right direction to make an angle the same size as ABC in the real world. Drawing most of it can be skipped. The only bit that is of interest is the bit of the line from B towards C which crosses the line from A to C which was drawn earlier. The right place on the map for C is where those lines cross! (It is the only point which is in the right direction from A AND in the right direction from B.)

So! That is how a map of three points is made. To do a more informative map, you just repeat the process again and again, taking bearings to other points from A and from B.

Earlier, we said that A and B could go almost anywhere on the map. This is true, but if you want to know the scale of the map, you need to know how far apart A and B are in the real world. Let's say they are 100 m apart. Put them 100mm apart on the map, and all over the map, 1mm will stand for 1m.

Go back to the top of the page and choose an aspect of all of this to explore further!

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