Platforms

 Platforms. Platforms refer to the structures or vehicles on which remote sensing instruments are mounted. The platform on which a particular sensor is housed determines a number of attributes, which may dictate the use of particular sensors.

Platform is the the vehicle carrying the remote sensing device .

Types of platforms

1. Ground-borne platforms: Ground borne platforms are used to record detailed i informationabout the surface which is compared with information collected from aircraft or satellite sensors i.e. for ground observation. Ground observation includes both the laboratory and field study, used for both in designing sensors and identification and characterization of land features Ground observation platforms include – handheld platform, cherry picker,towers, portable masts and vehicles etc. Portable handheld photographic cameras and spectroradiometers are largely used in laboratory and field experiments as a reference data and ground truth verification.

2) Air-borne platforms: Airborne platforms are used to collect very detailed images and facilitate the collection of data over virtually any portion of the Earth's surface at any time. Airborne platforms were the sole non-ground-based platforms for early remote sensing work.

3) Space-borne platforms: In space-borne remote sensing, sensors are mounted on-board a spacecraft (space shuttle or satellite) orbiting the earth. Space-borne or satellite platform are onetime cost effected but relatively lower cost per unit area of coverage, can acquire imagery of entire earth without taking permission. Space borne imaging ranges from altitude 250 km to 36000 km. Spaceborne remote sensing provides the following advantages:  Large area coverage;  Frequent and repetitive coverage of an area of interest;  Quantitative measurement of ground features using radiometrically calibrated sensors;  Semi-automated computerized processing and analysis;  Relatively lower cost per unit area of coverage

Sensors and multispectral scanners

 Sensor -

A sensor is a device that gathers electromagnetic radiations, converts it into a signal and presents it in a form suitable for obtaining information about the objects under investigation. Based upon the form of the data output, the sensors are classified into photographic (analogue) and non–photographic (digital) sensors. A photographic sensor (camera) records the images of the objects at an instance of exposure. On the other hand, a non–photographic sensor obtains the images of the objects in bit-by-bit form. These sensors are known as scanners.

Multispectral Scanners -

In satellite remote sensing, the Multi Spectral Scanners (MSS) are used as sensors. These sensors are designed to obtain images of the objects while sweeping across the field of view. A scanner is usually made up of a reception system consisting of a mirror and detectors. A scanning sensor constructs the scene by recording a series of scan lines. While doing so, the motor device oscillates the scanning mirror through the angular field of view of the sensor, which determines the length of scan lines and is called swath. It is because of such reasons that the mode of collection of images by scanners is referred bit–by–bit. Each scene is composed of cells that determine the spatial resolution of an image. The oscillation of the scanning mirror across the scene directs the received energy to the detectors, where it is converted into electrical signals. These signals are further converted into numerical values called Digital Number (DN Values) for recording on a magnetic tape.

The Multi-Spectral Scanners are divided into the following types:

(i) Whiskbroom Scanners

(ii) Pushbroom Scanners 

 Whiskbroom sensor 

Pushbroom sensor

(i) Whiskbroom Scanners : The whiskbroom scanners are made up of

a rotating mirror and a single detector. The mirror is so oriented that

when it completes a rotation, the detector sweeps across the field of view between 90° and 120° to obtain images in a large number of narrow

spectral bands ranging from visible to middle infrared regions of the

spectrum. The total extent of the oscillating sensor is known as the Total

Field of View (TFOV) of the scanner. While scanning the entire field, the

sensor’s optical head is always placed at a particular dimension called

the Instantaneous Field of View (IFOV). Figure 7.7 depicts the scanning

mechanism of whiskbroom scanners.

(i) Pushbroom Scanners: The pushbroom scanners consist of a number

of detectors which are equivalent to the number obtained by dividing the

swath of the sensor by the size of the spatial resolution (Fig. 7.8). For

example, the swath of High Resolution Visible Radiometer – 1 (HRVR – 1)

of the French remote sensing satellite SPOT is 60 km and the spatial

resolution is 20 metres. If we divide 60 km x 1000 metres/20 metres, we

get a number of 3000 detectors that are deployed in SPOT HRV – 1 sensor.

In pushbroom scanner, all detectors are linearly arrayed and each detector

collects the energy reflected by the ground cell (pixel) dimensions of 20 metres at a nadir’s view.

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Remote sensing - historical development, principle and process of remote sensing

 Introduction to remote sensing-

Evelyn Pruitt, a geographer with the U.S. Office of Naval Research, was the first to coin the term 'remote sensing’.

Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object. The term is applied especially to acquiring information about the Earth and other Planets . 

Remote sensing depends upon measuring some kind of energy that is emitted , transmitted, or reflected from an object in order to determine certain physical properties of the object.

     

In other words remote sensing is the art and science of deriving information about an object from measurements made at a distance from the object without coming in physical contact with it.

 there are many types of remote sensors . But these are chiefly divided in two categories-

1) active remote sensors – active remote sensors emit energy and then detect the emitted energy that gets reflected back off an object.

 Ex- photographic camera with flash, radar , laser, sonar etc.

2) passive remote sensors – the human eye and ear are passive remote sensors. Passive remote sensors do not EMIT energy but simply detect energy that is reflected back to the sensing device. The eye detects energy invisible portion of electromagnetic spectrum while ear detect sound and sound energy.

Remote sensing deals with the inventory ,monitoring and assessment of natural resources.

It has emerged as the major source of digital data for gis analysis .

This significance of remote sensing data is synoptic Vies , low relative cost , accuracy , receptivity.

It is widely used in underground water exploration , mineral exploration end of course mapping the remote and inaccesible areas.

Remote sensing is based on sensing electromagnetic energy emitted or reflected from the Earth surface and detected at some altitude above the ground.

Principle of remote sensing

 A) ENERGY SOURCE OR ILLUMINATION

 B) RADIATION AND THE ATMOSPHERE

 C) TERRAIN CONDITION

 D) RECORDING OF ENERGY BY THE SENSOR 

 E) TRANSMISSION, RECEPTION AND PROCESSING

 F) INTERPRETATION AND ANALYSIS

 G) APPLICATION

The base for most remotes sensing system is of measuring the varyng energy level of a single entity. Variations in energies are related to wavelength or frequency.

Electromagnetic radiation that varies from high to low energy levels comprises the electromagnetic spectrum.

Electromagnetic radiation-

Energy is capacity to do work. Energy can take many form such as light heat or sound and can be transmitted between objects through three process conduction convection and radiation. Radiation does not require physical contact or existence of a liquid or gas.

Environmental remote sensing system focus on electromagnetic energy which is dynamic form of energy caused by acceleration of an electric charge.

Each Photon consist of an electrical field which varies in magnitude and direction is perpendicular to the direction of the radiation, and a magnetic field oriented at right angles to the electric field.

Both these fields travel at the speed of light which is 3* 10⁸ m /s .

Two characteristic of electromagnetic radiation are particularly important for understanding remote sensing these are wavelength and frequency.

 c=λ⋅ν , where c is the speed of light, λ is the wavelength, and ν is the frequency.

Electromagnetic spectrum-

Depending on the physical and chemical properties, every object reflects emits or scatters a portion of electromagnetic energy which is unique radiation property over the electromagnetic spectrum. Electromagnetic spectrum is the ordering of radiation according to wavelength frequency or energy and use to identify and classify objects.

Source - 

The objects having a temperature of more than absolute zero radiate energy. The sun which is the earth’s only external form of heat m.Ed solar radiation mainly in the form of short wave visible and ultraviolet energy. It must be made clear at the stage that the type of light produced by an object will depend on its temperature

RADIATION AND THE ATMOSPHERE- 

All of the solar radiation passes through space to reach the top of earth atmosphere but not all reaches the earth at surface. The atmosphere scatters ,absorbs and reflects a portion of incoming solar radiation. The earth scatters absorbs and reflects the solar radiation that gets transmitted through the atmosphere.

Finally the atmosphere scatters absorbs and reflects the electromagnetic radiation that is reflected off the Earth surface back towards the sensor.

SCATTERING-

Scattering is the process by which small particle suspended in a medium of different index of refraction diffuse a portion of incident radiation in all direction.

Interaction of EMR with Earth surface -

On average 51% of the incoming solar radiation reaches the Earth surface. Of this 4% is reflected back into atmosphere and 47% is absorbed by the Earth surface to be radiated in the form of thermal infrared radiation. In general surfaces that are good reflectors are poor absorbers. Thus some surfaces or objects will reflect much of the incoming radiation while other surfaces will absorb most of the incoming radiation. The reflectivity of a surface can be measured for a specific wavelength or for the entire electromagnetic spectrum.

The ALBEDO often object is its reflectance aggregated over a broader segment of the electromagnetic spectrum eg: over visible portion of spectrum.

The higher the albedo the more reflective the surface and brighter the surface will appear in remotely sense imagery.

5) recording of energy by sensors - After the energy has been scattered by or emitted through the target We require a sensor to collect And record the electromagnetic spectrum. Sensors are devices made to measure photons. 

Two types – Active and passive sensors

6) 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 data Are processed into an image ( digital) 

Interpretation and analysis –

The interpretation Of processed image is done , Visually or digital to extract information about the target which was illuminated.

8) Application- 

The final element of remote sensing is achieved when we apply the knowledge that we have gained by the remote sensing in problem solving, studies , policy making or assist a particular problem .

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Jeremy Bentham - complete political thought , life , times , utility theory , theory of law, pleasure vs pain and greatest happiness principle

 Jeremy Bentham -

Bentham, the intellectual leader of English utilitarianism, who controlled the English political thought for 100 years was born in London on February 15, 1748.

Benthams parents saw in their child the markings of an intellectual genius .

When other children of his age spent their time in playing games, he read books. He started reading at the age of three.

He was admitted in queens College, Oxford where he matriculated at age of 13 and graduated at 15.

His early life was quite uneventful.

Since his father and grandfather were successful lawyers and built up a big fortune through their vast practice, young bentham entered Lincoln’s inn after his graduation in 1763.

Bentham was not interested to earn his livelihood through practice of law.

Bentham’s interest were in economics, logic, psychology, politics and ethics.

Throughout, his life Bentham advocated reforms of the legal system . he thought this department had become irrelevant and failed to meet the demands of an industrialized society.

However , he’s best known for his doctrine of utilitarianism.

Major works -

Fragment of government- 1776

Defence of usury – 1787

Introduction to the principles of morals and legislation- 1789

Essays on political tactics – 1791

Discourse on civil and penal legislation- 1802

A theory of punishment and rewards – 1811

A treatise on judicial evidence – 1813

The book of fallacies- 1824

Radicalism not dangerous- 1819

Church of englandism- 1818

Chrestomathia- 1816 

His ‘fragment of government’ Constituted a thorough analysis of and attack on the conservative principles of Blackstone.

‘Fragment’ was produced as an annihilating criticism of Blackstone.

In defence of usury he defended the lending of money at interest.

MAIN POLITICAL IDEAS OF BENTHAM -

Base of bentham’s ethical theory – 

“Nature has placed mankind under the governance of two sovereign masters , pain and pleasure. It is for them to alone point out what we ought to do , as well as to determine what we shall do .

Concept of utility-

“ by the principle of utility is meant that the principal which approves or disapproves of every action whatsoever, according to tendency which it as appears to have augment or diminished the happiness of the party whose interest is in question”

The principle of utility states that action and behaviors are right in so far as they promote happiness or pleasure, wrong as they tend to produce unhappiness or pain.

By utility is meant that property to any object, whereby it tends to produce benefits, advantages, pleasure, good or happiness.

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His clear dictum is – 

. Each and every government while formulating any policy or taking any decision or implementing any action regarding the management of state must remember that whether or to what extent that policy or action or principle is capable of maximizing comfort or pleasure of people.

The comfort or pleasure of people is of primary importance for every government.

Bentham said-

                it is in vain to talk of the interest of community, without understanding what the interest of the individual.

What Bentham emphasizes is that it would be unwise and undesirable to adopt any policy that will not be able to complete the interest of general public or will not be able to avoid being an augment quantity of pleasure.

In a word – the avoidance of pain and attainment of pleasure shall be the guiding principle of any government policy.

In every Sphere of life and in every action man’s sole guide is the calculation of pain and pleasure.

FELICIFIC CALCULUS- MEASURING UTILITY 

The highest principle of morality is to maximize happiness, the overall balance of pleasure over pain.

In considering whether an action is good we must consider how much pleasure it would produce along seven dimensions –

1) intensity

2) duration

3) certainty or uncertainty

4) propinquity or remoteness

5) fecundity

6) purity

7) extent.

Men obey laws because, The problem mischief of obedience are less than probable mischiefs of disobedience.

THE PLEASURE VS PAIN THEORY- 

Pleasure versus pain is the mainspring of all human actions.

According to Bentham , an act is right if it produces happiness ( surplus of pleasure over pain ) and wrong if it produces unhappiness ( surplus of pain over pleasure) .

It means that the moral worth of an act is to be measured by its usefulness in promoting pleasure and not by its inherent quality.

There are generally four sources of pleasure and pain which are distinguishable from each other- 

1) physical

2) moral

3) religious

4) political 

An important part of bentham’s theory of pleasure and pain consists of calculation or what may be called measurement.

If pain and pleasure cannot be measured, it would not be an easy task for individual to take decision or arrive at conclusion.

The diffusion of pleasure and avoidance of pain are only ends which are more listed and legislator should always have in view. 

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The principal of greatest happiness- 

‘The object of legislation of state is to promote and secure the greatest happiness of greatest number.’

According to Bentham state is evidently fictitious.

The greatest happiness principle means that the real significance of a law or an institution must be judged in terms of what it does to specific individuals.

The worth of law And government must be in their effects upon the lives of actual men and women.

For him , quantity of pleasure is important – push pin is as good as poetry.

the theory of law and reforms - 

–Since Bentham was a man of Jurisprudence and had special attachment to it, it is quite natural that legislation will receive added significance in his political writings .

–The theory of law is its consequence.

–Individuals obligation to the law is to be determined by its capacity to satisfy the utility. So the law is to be enacted in such a way as to fulfill this basic demand. Naturally the person who takes the leading part in enactment of law must know the requirement of people.

–In bentham’s society the legislator had very crucial part to play.

–Bentham rejected the social contract theory of government as  nonsense .

According to him men obey laws of government because, “ the probable mischiefs of obedience are less than the probable mischiefs of resistance.”

He said , “ there is no right which when the abolition of it is advantageous society shouldnot be abolished.”

He criticized existing laws and method of executing them.

Most of the law reforms since Bentham’’s days can be traced to his influence.

Justice in fact, in England, in Bentham’s Day was Not done But it could be purchased and could be purchased by those who could pay the highest price for it.

Bentham also condemned delay and denial of justice on part of judges.

Law , he insisted was not a mystic mandate of reason or nature, but simply the command of that authority to which the members of community render habitual obedience.

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Utilitarianism concept

   UTILITARIANISM- 

•UTILITARIANISM is a product of English mind , it is generally associated with JEREMY BENTHAM.

The theory believes that man is Social by nature and is always chiefly motivated in life by the desire to obtain happiness or avoid pain and that the happiness of each individual involves relation with other individuals, which necessitates state regulation of mutual relations of men by legislation.

Utilitarianism is a theory of morality that advocates actions that foster happiness or pleasure and oppose actions that cause unhappiness or harm. When directed toward making social, economic, or political decisions, a utilitarian philosophy would aim for the betterment of society as a whole.

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Utilitarianism is a philosophy which is based on hard realities of human existence.

The doctrine demands that utility should be basis of all social , political and ethical endeavours. In the hands of notable English exponents, Bentham and mill , it became a principle of state legislation.

The utilitarian philosophy is primarily ethical theory.

The object of legislation of state is to promote and secure ‘The greatest happiness of greatest number.’

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•The criteria of right and wrong of Good and bad, which the state should apply, is found in happiness and not in abstract principle of reason.

•polity is thus subordinated to ethics and in its actions utility is the measure of right.

•Utilitarianism represent interest in the welfare of mankind .

•Utilitarians are mostly individualistic.

The utilitarians reject every form of contract, consent or agreement theory as a basis for political obligation. 

CRITICISM

1)it’s major criticism is over simplification , in reality people do not desire pleasure or avoid pain, they desire object whose realization gives them pleasure and non realization pain..

2)It has been branded as of selfish and egoistic character.

3)Happiness depends upon the mental condition of human beings and is independent of the activities of state ( pleasure is individualistic) .

4)Utilitarianism lacks idealism as it is mainly concerned with the actual needs of individuals.

Utilitarianism has no theory of state to offer , what it gives us is a theory of government.

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