Why can't Indians access maps for 43 per cent of their country?
Hilltop to desktop
Technology advances have transformed the way maps are made
When the Survey of India (SoI) was set up 237 years ago, in Dehradun, map making was akin to pure art. It required steady hands and a keen eye, and demanded months, at times years, of painstaking labour. The first maps were made on parchment using brushes.
The actual mapping of the land was an arduous process -- it involved iron chains (as a standardised unit of measure), and large theodolites (survey instruments which measure vertical and horizontal angles) weighing as much as 500 kilogrammes. The theodolite needed 12 people to haul it to vantage positions on hilltops, for map makers to accurately create a grid of landmarks.The mapping of India began in 1800 and it took more than 50 years to cover 2,575 kilometres with inch-perfect accuracy. Thus was created the Great Indian Arc of the Meridian -- a grid of reference points useful for all maps.
But that was 'back then'
Today, high-end computer processing and off-the-shelf satellite imagery (of course, at a price) make it possible to process maps, quite literally, from desktops. Also, high resolution satellite imagery obviates the need for extensive physical labour and surveys. One can now access finely resolved maps of any part of the world; one can single out a mango tree in a field or a car in a porch. These satellite images are available in the public domain. Spy satellites with far higher resolution capabilities, elusive for commoners, outdo even such super close-ups. A highly powerful tool for map making now is the Geographic Information Systems (GIS) which literally brings maps to life (see box: Layers of an onion).
Modern maps are also far more accurate than hand-drawn ones. For instance, for a cartographer tracing a line a millimetre thick on a map made to the scale of 1:1,50,000 (so a millimetre on the map would be 15 metres on the ground), a minor deviation of a centrimetre on the state boundary means as much as 1.5 kilometres on the ground. Digital map making reduces this error to a few millimetres. Advances in printing technology ensure high quality maps are easily available.
The digital revolution has democratised the making of maps. Unfortunately, it has not democratised the use of maps. Not in India. Not till date.
||First Survey General of Bengal appointed
||The great trigonometric arc survey starts
|| George Everest appointed Survey General
||Cape Comorin to Mussoorie survey completed
||Mt Everest measured
||Magnetic survey begins
||First series of metric maps begins
||Satellite-based mapping initiated
||Global Positioning System introduced
||National Spatial Database Infrastructure mooted