1 Republic of Iraq Ministry of Higher Education and Scientific Research University of Technology REMOTE SENSING Third Class First Edition (2010)Laser Branch Department of Applied Sciences University of TechnologyDr. Abdulrahman K. Ali REMOTE SENSING
2 Remote Sensing:is the collection of information relating to objects without being in physical contact with them. Thus our eyes and ears are remote sensors, and the same is true for cameras and microphones and for many instruments used for all kinds of applications Or, said another way: Remote sensingis the process of acquiring data/information about objects/substances not in direct contact with the sensor, by gathering its inputs using electromagnetic radiation or acoustical waves that emanate from the targets of interest. An aerial photograph is a common example of a remotely sensed (by camera and film, or now digital) product. Introduction The sun is a source of energy or radiation, which provides a very convenient source of energy for remote sensing. The sun's energy is either reflected, as it is for visible wavelengths, or absorbed and then reemitted, as it is for thermal infrared wavelengths. There are two main types of remote sensing: Passive remote sensing and Active remote sensing. 1-Passive sensorsdetect natural radiation that is emitted or reflected by the object or surrounding area being observed. Reflected sunlight is the most ActivePassive
3 common source of radiation measured by passive sensors. Examples of passive remote sensors include film photography, infrared, and radiometers. 2-Active remote sensing, on the other hand, emits energy in order to scan objects and areas whereupon a sensor then detects and measures the radiation that is reflected or backscattered from the target. RADAR is an example of active remote sensing where the time delay between emission and return is measured, establishing the location, height, speeds and direction of an object. Overview Remote sensing makes it possible to collect data on dangerous or inaccessible areas. Remote sensing applications include monitoring deforestation in areas such as the Amazon Basin, the effects of climate change on glaciers and Arctic and Antarctic regions, and depth sounding of coastal and ocean depths. Military collection during the cold war made use of stand-off collection of data about dangerous border areas. Remote sensing also replaces costly and slow data collection on the ground, ensuring in the process that areas or objects are not disturbed.Applications of Remote Sensing There are probably hundreds of applications - these are typical: Meteorology- Study of atmospheric temperature, pressure, water vapour, and wind velocity. Oceanography: Measuring sea surface temperature, mapping ocean currents, and wave energy spectra and depth sounding of coastal and ocean depthsGlaciology- Measuring ice cap volumes, ice stream velocity, and sea ice distribution.