Basic Concepts of Remote Sensing

My Name is Somnath Goswami. Now I am studying MSc in Geoinformatics at Bankura University. Thank you for watching.

1. BASIC CONCEPTS OF REMOTE SENSING SOMENATH GOSWAMI UID NO.- 21143031032 MSc In GEO-INFORMATICS 1 St Semester P.R.M.S. MAHAVIDYALAYA BANKURA UNIVERSITY

2. 1 Introduction ‘Remote’ means ‘far away’ and ‘Sensing’ means ‘Believing or Observing some information, So ‘Remote Sensing’ means ‘Observing some information from Far away’. Definition: Remote Sensing is the collection of information about an object without being in direct physical contact with the object. This is done by sensing and recording reflected or emitted energy and processing, and analyzing that applying information.

3. Types of Remote Sensing System There are Different Types of Remote Sensing System Based on Source of Energy Passive Remote Sensing System (Ex- Camera) Active Remote Sensing System (Ex- RADAR,LIDER) Based on Range of Electro-magnetic Spectum Optical Remote Sensing System Pancromatic Imaging System Multispectral Imaging System Superspectral Imaging System Hyperspectral Imaging System Thermal Remote Sensing System Micro-wave Remote Sensing System 2

4. Processes and Elements of Remote Sensing Data Acquisition Source of Energy Radiation & Atmosphere Interaction with Targets Recording of Energy by Sensor Transmission & Reception Data Analysis Interpretation and Analysis Application 3

5. Electro-magnetic Radiation The foundation of remote sensing technology is based on the measurement and interpretation of the patterns of EMR. EMR is a dynamic form of energy. EMR transmit cross space in the wave form and in the speed of light. The whole range of EMR is called spectrum. The Sun light is the Exampel of EMR Wave Velocity Wave Langth Wane Frequency 4

6. Electro-magnetic Spectrum The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. Human eyes can only measure visible light but sensors can measure other portions of EMS. 5

7. Energy Interaction With Atmosphere Transmission of Energy- The release of energy from a substance is called energy transmission. When the energy of an electromagnet is transmitted through a medium without any change, it is called Transmission. Refraction of Energy- Refraction is a feature of the flow of light where light rays bend towards the speed of light to change the density of the medium as it enters from one medium to another. Reflection of Energy- Reflection means that they are thrown back from a surface Absorption of Energy- Absorption means that they are incorporated by a surface. Different surfaces reflect and absorb differently. The ratio between absorption and reflection is called albedo . Scattering of Energy- When energy waves (such as light, sound, and various electromagnetic waves) are caused to depart from a straight path due to imperfections in the medium, it is called scattering. 6

8. Atmospheric Window The Atmosphere absorbs some this to pass through. The places where energy passes through are called ‘Atmospheric Window’. An atmospheric window is a range of wavelengths of the electromagnetic spectrum that can pass through the earth's atmosphere. The optical, infrared and radio windows comprise the three main atmospheric windows. We use these "windows" in remote sensing to peer into the atmosphere from which we can obtain much information concerning the weather. 7

9. Sensor In remote sensing management, a device that receives incoming electromagnetic radiation and converts it into a digital electronics signal, is called Sensor. Active Sensor- Sensors that artificially collect energy from source of energy are called Active Sensor. (Ex- RADAR) Passive Sensor- Sensors that collect reflected electromagnetic radiation from natural source are called Passive Sensor. (Ex- LISS-I) 8

10. Platform Platforms are used to house the sensors which obtain data for remote sensing purposes. The distance between the target being imaged and the platform, plays a large role in determining the detail of information obtained and the total area imaged by the sensor. Platform are- Groundbrone Platform- Such platforms are related to the land and any object is photographed from above the ground. Airborne Platform- This is called an airborne platform where pictures can be taken at an altitude of 160 km above the ground Spaceborne Platform- The Spaceborne Platform is an artificial satellite that can collect images or data of the Earth's surface from a height of more than 160 kilometers above the Earth's surface. 9

11. Satellite System Satellite- an artificial body placed in orbit around the earth or moon or another planet in order to collect information or for communication. Geo-Stationary Satellite- Geo-Stationary Satellites are artificial satellites that orbit the earth from west to east at a time equal to the speed of the earth's orbit. Sun- Syncronous Satellite- Artificial satellites orbiting from north to south pole orbit according to Kepler's formula, consistent with the apparent angle of the sun, are called Sun- Syncronous Satellites. Sarellite Orbit- The path on which a satellite orbits its satellite on a specific surface is called orbit 10

12. 11 Resolution Definition: the ability to distinguish between different subject areas and elements of a satellite image is called resolution. Resolution can be divided into four parts – Spectral Resolution Spatial Resolution Radiometeric Resolution Temporal Resolution

13. 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 identification of large features. Repetitive coverage allows monitoring of dynamic themes like water, agriculture etc. Disadvantages of Remote sensing- Expensive for small areas, particularly for one time analysis. Requires spedalized training for analysis of images. Large scale engineering maps cannot be prepared from satellite data. Advantages and Disadvantages of Remote Sensing 12

14. Topography and cartography- Improving digital elevation models. Forest- monitoring the health of crops, mapping soil moisture. Hydrology- Assessing water resources from snow, rainfall and underground aquifers. Disaster warning and assessment- Monitoring of floods and landslides, monitoring volcanic activity, assessing damage zones from natural disasters. Planning applications- Mapping ecological zones, monitoring deforestation, monitoring urban land use. Applications of remote sensing 13

15. Remote sensing is the essential tool for prediction, detection and relief from natural and man-made disasters It is the only way to obtain unbiased data repetitive coverage. The remote sensing is restricted to methods that electromagnetic energy. Remote sensing data include multiple air photos, radiometer and photometer. Conclusion 14

16. Thank you 15