SHREE SWAMI ATMANAND SARASWATI INSTITUTE OF

TECHNOLOGY

Prepared By:-Karm Balar

REMOT SENSING

CONTENTS :-

Remote sensing – definition Concept of remote sensing History of remote sensing Advantages of remote sensing Disadvantages of remote

sensing Principle of remote sensing Elements of remote sensing Remote sensing platform Remote sensing software

REMOTE SENSING – DEFINITION

Remote Sensing is the science and art of obtaining information about an object, area, or phenomenon through the analysis of data acquired by a device that is not in contact with the object, area, or phenomenon under investigation.

Remote sensing is the acquiring of data about an object without touching it.

Remote Sensing Systems

Human eye Camera Radiometer Radar Sonar Laser

Passive

Active

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CONCEPT OF REMOTE SENSING

We perceive the surrounding world through our five senses. Some senses (touch and taste) require the contact of our sense organs with the object. However, we acquire much information about our surrounding through the senses of sight and hearing which do not require close contact between the sensing organs and the external object.

The technical term ‘remote sensing’ was first used in in the US in the 1960s. Technical term like encompassed photogrammetry, photo-interpretation and photo-geology also were emerged with remote sensing. Since landsat-1, the first earth observation satellite was launched in 1972, remote sensing has become wildely used.

HISTORY OF REMOTE SENSING Aerial photography is the original form of remote sensing (using

visible spectrum) started in 1909

Aerial photographic reconnaissance was widely used after 1915 in WWI.

Photogrammetric Engineering, the official monthly publication of the American Society of Photogrammetry, was first published in 1934.

Color infrared photography began 1931, then was widely used in agriculture and forestry.

Development of radar (1930-1940).

During WWII, non-visible spectrum (infrared and radar) were used as tools in remote sensing.

After the first man-made satellite (Sputnik 1) was launched on 4 October 1957 by Soviet Union, remote sensing moved to outer space, ignited the Space Race within the Cold War.

The United States' Explorer 6 transmitted the first space photograph of the Earth in August 1959.

The first systematic meteorological satellite observation came with the launch of the United States' TIROS 1 in 1960.

Landsat 1 (originally called the Earth Resources Technology

Satellite or ERTS) was the first satellite to collect data on the Earth's natural resources. It was launched on 23 July 1972.

Hyperspectral remote sensing emerged (1980s), widely used in mineral, oil, etc. exploration.

Since then, a large number and advanced types of remote sensing systems have been developed.

ADVANTAGES OF REMOTE SENSING Satellite images are permanent records, providing

useful information in various wavelengths. Large area coverage enables regional surveys on a

variety of themes and indentification of large features.

Repetitive coverage allows monitoring of dynamic themes like water, agriculture etc.

Easy data acquisition at different scales and resolution.

Amenability of remotely sensed data for fast processing using a computer.

The images are analysed in the laboratory thus reducing the amount oh firld work.

Map revision at medium to small scales is economical and faster

Color composite can be prodused from three individual band images, which provide better details of the area than a single band image or aerial photograph.

Flods over a large region, or the forest fire can be located from above and rescue planning can be immediately arranged.

The inaccessible areas like volcanic eruption, failure of dam over river, etc. can be covered by the remote sensing techniques to study the intensity of disaster

DISADVANTAGES OF REMOTE SENSING

Expensive for small areas, particularly for one time analysis,

Requires specialized training for analysis of images.

Data interpretation can be difficult

need to understand theoretically how the instrument is making the measurements

need to understand measurement uncertainties

need to have some knowledge of the phenomena you are sampling

Expensive to build and operate!!!!

Measurement uncertainty can be large

Powerful active remote sensing systeam, such as radars or lasers that emit their own EMR (electromagnetic radiation), can be intrusive and affect the phenomenon being investigated

PRINCIPLE OF REMOTE SENSING

The sun and various artificial sources radiate electromagnetic energy of variable wavelengths.

All objects on the surface of the earth have spectral signatures. A spectral signature of an object or ground surface is a values for the reflectance or radiance the feature.

The electromagnetic energy interacts with the earth’s surface and various features like buldings, bared soil, grass, water,paved road, forest etc.

The knowledge of spectral signature is essential for exploiting the potential of the remote sensing techniques. This knowledge enable one to identify and classify objects.

When radiation is incident on a surface, it is reflected, adsorbed, scattered and transmitted. All the processes are strongly dependent on the wavelength of the incident radiation, as well as the atomic and molecular structure of the material. In view of these facts, one can identify the material constituting the object from a spectral plot, multiband photograph or any other record, which shows enough details of its spectral reflection, absorption, scattering or transmission properties

ELEMENTS OF REMOTE SENSING

Energy Source or Illumination - the first requirement for remote sensing is to have an energy source which illuminates or provides electromagnetic energy to the target of interest.

Radiation and the Atmosphere  - 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.

Interaction with the Target - 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 radiation.

Recording of Energy by the Sensor  - 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 electromagnetic radiation.

Transmission, Reception, and Processing  - 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).

Interpretation and Analysis - the processed image is interpreted, visually and/or digitally or electronically, to extract information about the target which was illuminated.

Application - 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 particular problem.

REMOTE SENSING PLATFORMS Satellite-based

AIRPLAN-BASED

GROUND BASE