Introduction to Remote Sensing

P re s e n t e d b y :- Vivek Kumar

:- Bs( 1 s t Ye a r)

ContentsWhat is Remote Sensing ?What is Satellite Remote Sensing ? What is Earth

Observed?Introduction to the basic elements in Remote SensingThe Sensors Passive Sensors & Active SensorsThe Pixel The Spatial Resolution

What is Remote SensingIt is a method of collecting information about an object without the instrument being used to collect the data, coming in direct with the object.In other words it means, ‘measuring at a distance without physical contact’.

Like, Eyesight is a form of remote sensing. When we take a photograph of an object, the EMR (Electromagnetic Radiations) is recorded on the film.A scanner in a satellite also records EMR. The picture taken from a satellite is referred to as an ‘image’.

What is satellite Remote Sensing? What is Earth ObservedThere are a great number of satellites in orbit around the earth. They have designed, built and launched in order to relay images of our planet back to earth.(application in areas such as scientific research, industry, environment, engineering, urban planning,agriculture, meteorology, education, business, other areas of people related activities and in policies adopted by government)Remotely sensed information is most widely used in the application of urban, agriculture, disaster monitoring, oil spill monitoring etc.

Introduction to the basics elements in Remote Sensing

The object to be observedThe instrument or sensors to observe

the target The form of the ‘information’ obtained from remote sensing, and the method of storage A platform to hold the instrument

The SensorsA sensor is a device used to acquire a Photograph or an image. What a sensor Will do is, it will ‘sense’ and measure the Amount of radiated energy reflected From an object and record it.

Although the camera is a type of sensor, the word ‘sensor’ is normally used for the device used to Acquire images in remote sensingIn satellite remote sensing, the types of sensors used of

capturing radiation from many differenet parts of the electromagnetic spectrum, which are visible to the human eye.

Passive Sensors & Active SensorsPassive Sensors

A sensors will record information reflected from Earth surface features. A sensor, which measures

wavelengths Reflected or emitted by the objects under observations, is

calledA ‘ passive sensor’.

Active SensorsA ctive sensors ‘emits’ radiation that reflects off objects and

only theLittle energy returned to the sensor is measured. The most

common Active sensor used in remote sensing is ‘radar’.

The PixelA given data set or image, can be represented by a

great number of pixel. A pixel is the smallest unit on a satellite image. A pixel is generally equivalent to one word or byte. (sometimes 2 bytes)

Displayed in the correct order all the pixels build up a meaningful image

For examples, if the observed object is a green plant and the sensor is specially made to detect green, the intensity will be very high. If we use the same sensor to observed a red object, the intensity will be very low

The value of the pixel varies from 0 to255 displayed on a screen as gray levels ranging from black(0) to white(255)

Spatial Resolution

The spatial resolution or ground of an image is the smallest size of a feature that the sensor is able identify.

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