2. Contents
What is Remote Sensing ?
What is Satellite Remote Sensing ? What is Earth Observed?
Introduction to the basic elements in Remote Sensing
The Sensors
Passive Sensors &Active Sensors
The Pixel
The Spatial Resolution

3. What is Remote Sensing
It 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’.

4. What is satellite Remote Sensing? What
is Earth Observed
There 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.

5. Introduction to the basics elements in
Remote Sensing
The object to be observed
The 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

6. The Sensors
A 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 sensing
In 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.

7. Passive Sensors & Active Sensors
Passive Sensors
Asensors will record information reflected from
Earth surface features.A sensor, which measures wavelengths
Reflected or emitted by the objects under observations, is called
A‘ passive sensor’.
Active Sensors
Activesensors ‘emits’radiation that reflects off objects and only the
Little energy returned to the sensor is measured. The most common
Active sensor used in remote sensing is ‘radar’.

10. The Pixel
A 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)

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

14. Thank-you