RS_GIS_GPS.pdf
- 1. 2 What is Remote Sensing? Remote sensing is a method of obtaining information about the properties of an object without coming into physical contact with it.
- 2. What is remote sensing used for? Remote sensing is a method for getting information about of different objects on the planet, without any physical contacts with it.
- 3. The art, science and technology of obtaining reliable information about physical objects and the environment, through the process of recording, measuring and interpreting imagery and digital representations of energy patterns derived from noncontact sensor systems. 4
- 4. • “Remote sensing is the noncontact recording of information from the ultraviolet, visible, infrared, and microwave regions of the electromagnetic spectrum by means of instruments such as cameras, scanners, lasers, linear arrays, and/or area arrays located on platforms such as aircraft or spacecraft, and the analysis of acquired information by means of visual and digital image processing.” 5
- 5. Three essential Components of Remote Sensing: 1. The Signal (from an object or phenomena) 2. The Sensor (From a platform), and 3. The sensing (Acquiring knowledge about the object or the phenomenon after analysis of the signals, received by the sensor at the users library )
- 6. Remote Sensing Process/Concept Components Emission of EMR (Sun/Self emission) (A) Transmission of energy from the source to the surface of the earth (absorption and scattering) (B) Interaction of EMR with the Earths surface (reflection & emission) (C) Transmission of Energy from the surface to the remote sensor (D) Sensor data output (E) Data transmission, processing and Analysis (F) Application (G) 7
- 9. Satellite Remote Sensing of Earth
- 10. Electromagnetic Energy It is the emission of energy from any object having temperature of absolute zero (00K or -273.150C). Electromagnetic wave corresponds to oscillations of the electric and magnetic field vectors perpendicular to each other and perpendicular to the direction of wave propagation. If the wave is traveling in the "x" direction (the thumb), The electric field is oscillating in the "y" direction (index finger), and The magnetic field is oscillating in the "z" direction (the middle finger).
- 11. It is the total range of radiation from short wave to long wave. In other words, it is the continuous sequence of electromagnetic energy arranged according to wavelength and frequency.
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- 16. Platforms carry sensors… • Platforms are airplanes, satellites, balloons, kites, towers, helicopters etc. • Passive sensors are like cameras – Record reflected radiation – Visible, infrared, ultraviolet, thermal – Most common: Air photos and most satellites • Active sensors – Emit radiation and record the reflectance – Microwave, Radar, Sonar, Lidar
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- 18. Geostationary Orbit GOES satellites orbit the earth above the equator at the same speed as the earth rotates so that they can transmit continuous pictures of the region below : 19
- 19. Polar Orbit Polar satellites are sun-synchronous, which means they are able to observe any place on the Earth and will view every location twice each day at different illuminations. Polar orbiting take about 100 minutes to travel from pole to pole and produce high resolution "snapshots” due to their closeness to the Earth. 20
- 20. Orbit Type Characteristics Considerations Geostationary •Orbits the earth above the equator at the same speed the earth rotates •Orbit is high - ~ 36,000 km •Can produce animations of the earth's weather patterns ❑ Good for tracking weather storms ❑ Can observe changes in time ❑ Can not see the poles very well ❑ Can view only one hemisphere ❑Image resolution is not very good because of distance from earth Polar • Orbit around North and South Poles •Orbits are lower altitude (~700- 800 km) •Takes about 100 minutes to travel from pole to pole •Produces high resolution “snaps shots” of the earth ❑ Image resolution is good because it’s closer to earth ❑ Sees the poles a lot (~14 times a day) ❑ Sees the given tropical and middle latitude regions of the globe twice a day at different illumination. ❑ Used for a variety of applications, including air quality, land cover, water quality, and vegetation studies Basics of Observation from Satellites
- 21. • A digital image comprises of a two dimensional array of individual picture elements called pixels arranged in columns and rows. Each pixel represents an area on the Earth's surface. Each pixel has an intensity value (represented by a digital number) and a location address in the two dimensional image.
- 25. Spectral Signature • The term spectral signature refers to the relationship between the wavelength (or frequency) of electromagnetic radiation and the reflectance of the surface. • A spectral signature is some measurable quantity (e.g., reflectivity, emissivity), which varies as a function of wavelength and can be used to identify a material. • The signature is affected by several things including the material composition and structure. Some parts of the EMR spectrum, such as the microwave region, are more sensitive to surface structure than other regions.
- 27. Spectral Reflectance Curves ◼ The % of incident energy that is reflected from an object usually varies as a function of wavelength. ◼ This variation can be displayed in the form of a spectral reflectance curve. Visible portion of EM spectrum
- 29. Advantages of Remote Sensing • Provides a view for the large region • Offers Geo-referenced information and digital information • Most of the remote sensors operate in every season, every day, every time and even in real tough weather • Permanent and reliable record • Cost effective and reliable • Able to see number of terrain feature in one scene
- 30. • Crop inventory • Crop Growth monitoring, • To estimate the crop biomass, LAI etc., • Crop acreage estimation • Crop condition monitoring • Stress determination in crop • Crop Yield Forecast. Applications in Agriculture
- 31. ➢ Natural Resources mapping such as river, drainage system, water province etc., ➢ To draw information on phenology of the crop, ➢ Nutrient management, ➢ Moisture stress, ➢ Pest and Disease detection and extent mapping, ➢ Soil mapping, ➢ Organic matter and nutrient status detection, ➢Precision Farming, ➢Cropping System Analysis, Cont….
- 32. What is GPS? 33 The Global Positioning System (GPS) is a satellite based navigation system made up of a network of 24 satellites placed into orbit by U.S. Department of Defense. GPS works in any weather conditions, any where in the world , 24 hours a day. NAVIC own GPS of India ➢India’s own navigational system will be called NAVIC (Navigation with Indian Constellation) was launched on board the Polar Satellite Launch Vehicle (PSLV). ➢It is launched at Satish Dhawan Space Centre, Sriharikota, Andhra Pradesh on April 28, 2016 at 12:50 p.m. ➢ Indian Space Research Organisation (ISRO) have launched 7th satellite for the purpose of GPS navigation. ➢It will cover 20,657 km from the earth.
- 33. GPS ➢ GPS is composed of a constellation of orbiting satellites which in conjunction with ground equipment enable users to determine their exact position anywhere on the surface of the earth at any time. 34 Global Positioning System
- 34. GPS Constellation 24 Satellites in 6 orbital planes 4 satellite in each plane Orbital period- 11 hr 58 min Altitude- 20,200 km Orbital radious-26,600 km Separation- 60° Inclination - 55 ° 35 NAVSTAR NAVigation Satellite Timing And Ranging
- 37. The GPS system consists of three segments 1. The Space Segments Comprising the satellites and transmitted signals 2. The Control Segments The ground facilities carrying out the task of satellite tracking, orbit computations and supervision necessary for the daily control of the space segment. 3. The User Segment The entire spectrum of applications equipment and computational techniques that are available to the users. 38 Segments of GPS
- 38. 39 Uses of GPS 1) To know geo-coordiantes 2) To know altitude 3) To survey 4) For acreage estimation 5) Navigation 6) Transportation
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- 40. 41 Data vs. Information ➢Data, by itself, generally differs from information. ➢Data is of little use unless it is transformed into information. ➢Information is an answer to a question based on raw data. ➢We transform data into information through the use of an Information System.
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- 44. 45 Information systems can be very simple, such as a telephone directory.
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- 46. Geographic Information System (GIS) Tool for handling geographic (spatial and descriptive) data. It is an organized collection of computer hardware, software, geographic data and the personnel designed to efficiently capture, store, retrieve, update, manipulate, analyze and display all forms of geographically referenced information according to the user defined specifications. 47
- 47. Key Components of GIS Tabular & Geospatial data Hardware and Software Application/ Method People/ Users 48
- 48. 49 Sources of geospatial data Satellite images Attribute data/Statistical tables Digitized maps Aerial photographs
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