Accuracy and Application of Remote Sensing in Nepal
Punya Prasad Oli
P.O.Box. 9447
Handigau, Kathmandu-5
Tel. +977 1 438869
E-mail: p_oli@htp.com.np
Nepal
Abstract :
The aerial photography started in 1933 by photographing Mt. Everest areas. The accuracy of topographical and resources maps and information were improved using satellite remote sensing during 1970-1980s. The Remote Sensing Centre was establish in 1970s and disappeared in 1990s. Presently, satellite sensing is being used to study and management of land resources like forestry. In this article, is briefly described the ups and downs of remote sensing, applications, accuracy achieved and recommendation for the development of remote sensing in Nepal.
Introduction:
Remote Sensing is the science and technology of acquiring, processing, analysis of the object or area without touching or from remote and use of such data for decision making. The term was first used in 1960s in USA for photogrammetry and used extensively after launching the ERTS satellites in 1972.
It has three components of emitting or radiating object of the earth surface, the receiving sensor on platform in the aircraft or satellite, and receiving and processing station on the ground. Some cases the platform itself emits and receives the reflected or scattered ray back and forms image or receive data on the sensor.
The sensors may be active or passive and imaging or no imaging. The photography of Shuttle is passive, non-scanning and imaging type and Real Aperture Radar Imagery is the example of active, scanning and imaging sensors. They may be sensitised films, receiving lens, lenses or mirror consisting of series of detectors in arrays.
The detectors convert the received electromagnetic energy into electrical signals. They are amplified and transmitted to the receiving station directly or through satellite to the ground stations in binary signals of pixels. Both cases, the signal passes through atmosphere, which effects the signals/ images. Attitudes of sensors, detectors, orbit of satellite and duration of day also affect the received images or signals.
