Get to the Point: GIS and GPS

The US Geological Survey defines GIS or Geographic Information Systems as “a computer system capable of assembling, storing, manipulating, and displaying geographically-referenced information, that is, data identified according to their locations”. This means that different types of data (residing on a database) can be presented as layers, one on top of another, and then placed on a digitized map. With the explosion in computing, GIS experts can place different layers of data on a location to study cause and effect relationships of different hues. The advantage of GIS is that it can visualize and show you a 3 D scenario of a process or action in a few seconds or minutes that could otherwise take up a few weeks if done manually. 

GIS: 3D imaging in seconds



GIS is a boon for military commanders who are often deployed at a moment’s notice to different battlefield scenarios. And one of the essential skills needed to be in overall charge of military operations is making sense of terrain–topography and relief features from detailed maps and then formulating plans for troop movement. Traditionally, sand and mud relief models have been used to simulate possible offensive or defensive actions, say, for conducting a commando operation against a terrorist or outlaw like Veerappan holed up in a particular area. GIS models can help the commander brief his ‘boys’ about the topography, possible routes for infiltration, rescue of hostages and extraction of the special team after the operation. He can also simulate possible courses of action that the operation might take. For example, the commander could use it to simulate the effect of rain and slush and the subsequent delay these factors would have in an operation. 

Another real life example of GIS usage would be the recent rains in our metros, say in Delhi or Kolkatta. Using aerial photos, we can find out which localities are susceptible to waterlogging and where subsequent traffic jams build up, during or after a rain. Now relate this data with the traffic using a particular road during peak hours. Using a GIS model, it’s possible to predict how much the roads should be widened, what kind of drainage facilities should be provided, and how many buildings and people should be relocated to facilitate smooth flowing of traffic. A GIS system is made up of the required hardware, GIS software, a database and GIS experts. GIS is much more than digitized cartography. GIS can also be combined with GPS (Global Positioning System) receivers to simulate or study situations in real-time, say in moving supplies during times of emergencies or natural disasters.

Other possible and innovative uses of this new discipline would require a few pages by themselves. The Swedish Armed Forces have successfully used it for the production of tactical situation maps, planning convoys and even war gaming. The Indian Armed Forces are also looking at GIS tools with increased interest as part of the current upgradation process.

GPS: navigation system 



For thousands of years, stars, constellations, and astronomical devices were the only way to find out where you were at a particular moment. But today GPS has changed all that. GPS is a dynamic navigation system based on 24 Navstar satellites, each of which constantly revolves around the earth at a distance of 11,000 miles. Each satellite is placed in precise positions.

Using three satellites as reference points and triangulating (trilateration), a GPs receiver finds out the exact position (longitude and latitude) of any place on the earth. The GPS system uses some complicated techniques for this. 

A GPS receiver can do complicated measurements, triangulate, plot and give you the bearings in the matter of a few seconds, no matter wherever you are on the planet’s surface. It relies on increasingly compact, but high-performance circuits and chips to do this in a very short time. These can also correct imperfections in the calculations caused by factors such as gravity, multipath interference etc. Current civilian GPS models are accurate up to 40–100 m. Highly-accurate models that are correct to a few meters and in some cases centimeters are used in military applications.

An Indian story 



Indian defense personnel might in the future have tiny sensors implanted under their skins. These sensors will monitor parameters like blood pressure and heart rate, and relay it to a GPS receiver/transmitter fitted on the jawan’s uniform. Using satellite technology, the GPS transmitter in turn will relay it to a distant command post from where army doctors will be able to monitor their troops’ health. In the future these sensors will be programmed to change the soldier’s metabolic rate during emergencies or serious accidents. For example, the pulse of a seriously wounded soldier will be automatically reduced by the sensor or on a command from a doctor at the base hospital so as prevent blood loss and even death on the battlefront.

Benoy George Thomas