Remote sensing

It is the acquisition of information about an object or phenomenon without making physical contact with the object

1. Remote Sensing MASHHOOD ARIF

2. Contents Definition Types of Remote Sensing Elements involved in Remote Sensing Process of Remote Sensing Sensors Usual Platforms Interaction with Atmosphere Remote Sensing & GIS Aerial Remote Sensing Image Processing in Remote Sensing Types of Resolution Correction Advantages & Disadvantages of Remote Sensing Applications Conclusion

3. DEFINITION It is the acquisition of information about an object or phenomenon without making physical contact with the object In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals

4. TYPES (on basis of energy) Active Remote Sensing (artificial energy source)  Passive Remote Sensing (natural energy source)

5. TYPES (on basis of range of electromagnetic radiation ) Optical Remote Sensing (wavelength range 300nm-3000nm) Thermal Remote Sensing (wavelength range 3000-14000nm) Microwave Remote Sensing (wavelength range 1mm-1m)

6. ELEMENTS INVOLVED IN REMOTE SENSING Source of energy Radiation and the atmosphere Interaction with object Recording of energy by sensor Transmission, reception and processing Interpretation and analysis Application

7. PROCESS OF REMOTE SENSING Data acquisition Processing Analysis Accuracy assessment Information distribution to users

8. SENSORS Imaging Sensors Sensors which provide output to create image Example: LISS I, LISS II, LISS III, etc (Linear Imaging Self Scanning Sensor LISS) Non-imaging Sensors Sensors which provide numerical output with respect to quantum of radiation Example: Radiometer, Scatterometer , etc

9. USUAL PLATFORMS AIRCRAFT Helicopters Microlites Low altitude aircrafts High altitude aircrafts SATELLITE Orbiting satellites Geostationary satellites

10. INTERACTION WITH THE ATMOSPHERE Radiation used for remote sensing has to travel through Earth’s atmosphere Particles and gases in the atmosphere can affect it These effects are caused by mechanisms of scattering and absorption

11. Remote Sensing & GIS The science of acquiring information about the Earth using remote instruments, such as satellites It is inherently useful for disaster management Satellites offer accurate, frequent and almost instantaneous data over large areas anywhere in the world When a disaster strikes, remote sensing is often the only way to view what is happening on the ground

12. Remote Sensing & GIS (Contd..) Energy Source or Illumination (A) Radiation and the Atmosphere (B) Interaction with the Target (C) Recording of Energy by the Sensor (D) Transmission, Reception, and Processing (E) Interpretation and Analysis (F) Application (G)

13. Aerial Remote Sensing Aerial Remote Sensing Aerial photography is the most commonly used form of remote sensing and is widely used for topographic mapping, surveys for geological, soil and forestry mapping, engineering, town planning and environmental surveys on larger scale

14. IMAGE PROCESSING IN REMOTE SENSING Input data Reconstruction/ correction Transformation Classification Output

15. TYPES OF RESOLUTION Spatial Resolution The size of a pixel that is recorded in a raster image Spectral Resolution The wavelength width of the different frequency bands recorded Radiometric Resolution The number of different intensities of radiation the sensor is able to distinguish Temporal Resolution The frequency of flyovers by the satellite or plane

16. CORRECTION Radiometric correction Gives a scale to the pixel values Topographic correction In rugged mountains, as a result of terrain, the effective illumination of pixels varies considerably. The purpose of topographic correction is to eliminate this effect Atmospheric correction Elimination of atmospheric haze by rescaling each frequency band 

17. ADVANTAGES OF REMOTE SENSING Real time Spatial locations and extent of features can be corrected accurately Cheaper Faster Different scales Easy updation More analytical themes Remote sensors "see" over a broader portion of the spectrum than the human eye

18. DISADVANTAGES OF REMOTE SENSING Expensive to build and operate Measurement uncertainty can be large Data interpretation can be difficult

19. APPLICATIONS OF REMOTE SENSING Conventional radar is mostly associated with aerial traffic control, early warning, and certain large scale meteorological data Altimeters measure wind speeds and direction, and surface ocean currents and directions Light detection and ranging (LIDAR) is well known in examples of weapon ranging, laser illuminated homing of projectiles Radiometers and photometers are the most common instrument in use, collecting reflected and emitted radiation in a wide range of frequencies

20. RADAR LIDAR

21. APPLICATIONS OF REMOTE SENSING (Contd..) Stereographic pairs of aerial photographs have often been used to make topographic maps Hyperspectral imagers are used in various applications including mineralogy, biology, defense, and environmental measurements remote sensing allows to follow-up and monitor risk areas in the long term, to determine desertification factors

22. Conclusion Remote Sensing and GIS technology is very effective tool for suggesting action plans /management strategies for various disciplines The technique of obtaining information about objects through the analysis of data collected by special instruments that are not in physical contact with the objects of investigation