## How Maps were made before satellites?

Cartography or Map making is the procedure of making maps since ancient times. Right from the cave paintings to the maps of Greece, Babylon and on into the exploration to the 21st century, people have created and used maps to navigate their way throughout the world.

The first maps were made in almost the same way as they are made now, by using the method of surveying or of triangulation, even the satellites still use the same basic principles of triangulation to produce maps. Triangulation today is used for many purposes, including surveying, navigation, metrology, astrometry, binocular vision, model rocketry and gun direction of weapons.

Now to the actual method of mapping. Maps from the time of Ancient Babylonia were made by using accurate surveying techniques. Surveying is the technique of measuring the positions of different objects on the surface of the Earth by calculating the distances and angles between those points. The distances were measured by using ropes or chains of known lengths, while the angles were measured using physical or magnetic compasses. For calculating the angles between points which were far away from each other, they used magnifying glasses or small telescopes attached to compass.

The surveying table from CE1782. (source: wikipedia)

Triangulation is a way of determining the location of a certain point using the locations of other previously known points. With the triangulation method, distances, elevations and directions between objects at a great distance from one another can be determined. Since the early days of surveying, this was the primary method of determining accurate positions of objects for topographic maps of large areas.

A surveyor first needs to know the horizontal distance between two of the objects. Then the height, distances and angular position of other objects can be derived, as long as they are visible from one of the original objects. Although these techniques were known for long time, it was only towards the end of the 18th century that detailed triangulation network surveys were established to map whole countries.

The Great Trigonometric Survey of India began in 1801. The Indian survey had an enormous scientific impact; it was responsible for one of the first accurate measurements of a section of an arc of longitude, and for measurements of the geodesic anomaly.

Here is another example of pre-satellite era map (c. 18th century)

The Piri Reis Map compiled in 1513

The Piri Reis map is a pre-modern world map compiled in 1513 from military intelligence by the Ottoman admiral and cartographer Piri Reis. This was a map drawn from a collection of different maps available at that time. Now only 1/3rd of the map survives.

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