What is Remote Sensing

Remote Sensing Definition

Simple definition:

Remote Sensing is the collection of information about an object without direct contact.

Wikipedia definition:

Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object and thus in contrast to in situ observation.

Remote Sensing Applications

1. Land use mapping

2. Urban planning

3. Environmental applications

4. Global change and Meteorology

5. Hydrology and Coastal mapping

6. Forest and Agriculture applications

7. Telecommunication planning

8. Emergency and Hazards

Remote Sensing Advantages

1. Provides synoptic view (ability to see large area at the same time)

2. Reduces data acquisition time

3. Repetitive look at the same area at regular intervals for monitoring

4. Collecting data about areas that are physically inaccessible

5. Provides data in every weather and at any time of the day (though this depends on the type of RS method adopted)

Remote Sensing techniques

Passive Remote Sensing is the system which measures energy that is naturally available.

Active Eemote Sensing is the system which provides their own source energy for illumination

1. Optical technique

• Passive technique
• Camera, telescope used
• Infrared portion of electromagnetic spectrum used
• Relies on ambient light source (sunlight)
• Problems with cloud, rain, fog, snow.etc
• Only for surface (cannot penetrate vegetation, soil.etc

2. Microwave technique

• Passive technique
• Radar, radiometer used
• Microwave and Radio frequency portion of electromagnetic spectrum used
• Largely immune to cloud, smoke, precipitation

3. RADAR (RAdio Detection And Ranging)

• Active technique
• Transmites microwave (radio) signals towards scene and Recieves the portion of transmitted energy backscattered
• Observes the strength (detection) and time delay (ranging) of signal
• Operates in any time of day and through cloud cover

4. LIDAR (LIght Detection And Ranging)

• Active technique
• LASER (Light Amplification by Stimulated Emission of radiation) used
• Pulses of LASER emitted from sensor and reflected energy from target detected
• Time required for energy to reach target and return to sensor used to determine distance