6. Remote Sensing: A Definition
"Remote sensing is the science (and to
some extent, art) of acquiring information
about the Earth's surface without actually
being in contact with it.”
This is done by sensing and recording
reflected or emitted energy and processing,
analyzing, and applying that information.
7. • Remote Sensing:
–The art and science of obtaining information
about an object without physically contact
between the object and sensor
–The processes of collecting information about
Earth surfaces and phenomena using sensors
not in physical contact with the surfaces and
phenomena of interest.
–There is a medium of transmission involved
i.e. Earth’s Atmosphere.
8. • Remote sensing is a tool or technique similar to
mathematics using sophisticated sensors to measure
the amount of electromagnetic energy existing an
object or geographic area from a distance, and then
extracting valuable information from the data using
mathematically and statistically based algorithms is a
• Scientists are concerned with observing nature,
making careful observations and measurements, and
then attempting to accept or reject hypothesis
concerning these phenomena.
9. • The data collection may take place directly in
the field, or at some remote distance from the
object or area of interest.
• Data that are collected directly in the field are
termed as In Situ Data, and the data collected
remotely called Remote Sensing Data.
10. Remote Sensing Process
• Remote Sensing Process involves an interaction
between incident radiation and targets of interest.
Energy Source or Illumination (A)
Radiation and the Atmosphere (B)
Interaction with the Target (C)
Recording of Energy by the
Transmission, Reception, and
Interpretation and Analysis (F)
11. 1. Energy Source or Illumination (A)
The first requirement for remote sensing is to have an energy source which
illuminates or provides electromagnetic energy to the target of interest.
2. Radiation and the Atmosphere (B)
As the energy travels from its source to the target, it will come in contact with
and interact with the atmosphere it passes through. This interaction may take
place a second time as the energy travels from the target to the sensor.
3.Interaction with the Target (C)
once the energy makes its way to the target through the atmosphere, it interacts
with the target depending on the properties of both the target and the
4. Recording of Energy by the Sensor (D)
after the energy has been scattered by, or emitted from the target, we require a
sensor (remote - not in contact with the target) to collect and record the
5. Transmission, Reception and Processing (E)
the energy recorded by the sensor has to be transmitted, often in electronic form,
to a receiving and processing station where the data are processed into an
image (hardcopy and/or digital).
12. 6. Interpretation and Analysis ( F)
The processed image is interpreted, visually and/or digitally or electronically, to
extract information about the target which was illuminated.
7. Application ( G)
The final element of the remote sensing process is achieved when we apply the
information we have been able to extract from the imagery about the target in
order to better understand it, reveal some new information, or assist in solving a
13. Remote Sensing Organizations
ISPRS: International Society for photogrammetry and
NASA: National Aeronautical and Space Administration
ESA: European Space Agency (Europe)
NASDA: National Space Development Agency (Japan)
DARA: German Space Agency
CSA: Canadian Space Agency
NRSA: National Remote Sensing Agency of India
IGARSS: International Geosciences and Remote Sensing
14. Technical and Historical Perspectives
of Remote Sensing
1. Non-photographic Sensor systems
• 1800 Discovery of the IR Spectral region by sir
• 1879 Use of the bolometer by Langley to make
temperature measurements of electrical objects.
• 1889 Hertz demonstrated reflection of radio
waves from solid objects.
• 1916 Aircraft tracked in flight by Hoffman
using thermopiles to detect heat effects.
15. • 1930 British and Germans work on systems to locate
airplanes from their thermal patterns at night.
• 1940 Development of incoherent radar systems by the
British and United states to detect and track aircraft and ships
• 1950’s Extensive studies of IR systems at university of
Michigan and elsewhere.
• 1951 First concepts of a moving coherent radar system.
• 1953 Flight of an x-band coherent radar
• 1954 Formulation of synthetic aperture concept (SAR) in
• 1960’s Development of various detectors which allowed
building of imaging and non-imaging radiometers, scanners,
spectrometers and polarimeters.
16. 2. Photographic Methods
• 1840 photographic camera has served as a prime
remote sensor for more than 150 years.
• 1860 idea of aerial photography (photographing
the Earth’s surface)
• 1879 cameras on kites
• 1897 photos from small rockets from a height of
about 100 meters
• 1908 photos from airplanes, first by wilbur wright
(co-developer of first airplane)
• 1946 Start of space research
17. 3. Space Imaging/Observation Systems
• 1960 TV cameras- TIROS (Television
Infrared observation satellite ) used to scan wide
areas at a time (devoted to looking at clouds) low
resolution, black and white images.
• 1970’s High resolution images using the EM
spectrum beyond the visible into the near and
thermal infrared regions.
18. Classifications of Remote Sensing
• Remote sensing may be classified from many perspectives
like based on platform, source of energy, regions of
electromagnetic spectrum, number of bands, imaging media
• Classification based on Platform:
• Airborne remote sensing
• Space-borne remote sensing
• Classification based on energy source:
• Active remote sensing
• Passive remote sensing
• Classification based on imaging media:
• Photographic imaging remote sensing
• Digital imaging remote sensing
19. • Classification based on region of electromagnetic
• Optical remote sensing
• Photographic remote sensing
• Thermal remote sensing
• Microwave remote sensing
• Classification based on number of bands:
• Panchromatic remote sensing
• Multi spectral remote sensing
• Hyper spectral remote sensing
20. Advantages of Remote Sensing
• Provides a synoptic view, which is the ability to see large areas
at the same time. So it reduces the data acquisition time and
there by cost in comparison to the traditional surveying
• Remote sensing from satellite provides repetitive looks at the
same area at a regular time interval which helps in monitoring
several earth-surface features continuously.
• Remote sensing can be used for collecting data about areas that
are physically inaccessible.
• Remote sensors “see” over a broader portion of the spectrum
than the human eye. Some remote sensors operate in all
seasons, at night and in bad weather.
• Remote sensing science yields fundamental scientific
information or data systematically.
21. Remote Sensing Applications
• Land-use mapping
• Forest and agriculture applications
• Telecommunication Planning
• Environmental Application
• Hydrology and coastal mapping
• Urban planning
• Emergencies and Hazards
• Global change and Methodology
Urbanization & Transportation
ion of Remote Sensing
• Urban planning
• Roads network and
• City expansion
• City boundaries by time
• Wetland delineation
Image source: www.ldeo.columbia.edu
Image source: www.geospectra.net