Remote Sensing is a technique to collect information about objects without coming into contact with them. In the general sense, Remote Sensing helps in determining characteristics of the earth surface by measuring reflected and emitted radiation from a distance.
Remote sensing is a way to collect information without being physically present at a place. Satellites, drones and aeroplanes are the most common ways to collate such data. For instance, Antarctica is a rough terrain to visit for the purpose of collecting data. But with remote sensing, data related to ice sheets and ice caps, temperature, winds could be collected easily, safely and in a cost effective manner.
Remote sensors can be either active or passive. Passive sensors record the energy or electromagnetic spectrum that is either reflected or emitted from the earth surface, for e.g. the sunlight which is reflected after hitting various surfaces on the earth. On the other hand, active sensors project some form electromagnetic radiation to collect data, for e.g. a laser beam used by a sensor reflects back to it thereby providing information about the surface it hit.
Remote sensing makes data collection becomes efficient, fast and safe. Data of different types concerning various levels helps in aspects such as better planning and decision taking.
Here we limit our scope of study to the geographical applications of Remote Sensing. Remote sensing is useful in creating, analyzing and comparing data pertaining to forestry, weather, vegetation, pollution, erosion, groundwater, estimation of crop yield, land use patterns. It is also used to detect minerals and ores. Military satellites also use Remote sensing technology to spy and gather information. Keeping in mind all the multitudes of application remote sensing provides, they become indispensable in the development of a country. They possess immense potential to help policy makers, agencies and even private bodies to utilize the resources of a country in an efficient, planned and best possible manner.
Change detection, terrain mapping or modelling, slope aspect analysis, land cover classification, coastal ecosystem management; various mapping- forestry, agricultural, mining, geology, environmental impact assessment are some of the Remote Sensing services. These services are provided by a range of GIS based service providers.