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Basics of RS and GIS

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The presentation was compiled through online sources available. It was discussed during a lecture held on 16-02-2017 at the B. M. C. E. T. Surat for the BE II Civil Engineering Students. The focus of discussion was to create a sensitization about Remote Sensing and Geographical Information System among the students.

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Basics of RS and GIS

  1. 1. Lecture on Dt. 16-02-2017 at BMCET, Surat Basics of Remote Sensing and GIS Bhasker V. Bhatt PG in-charge (ME TCP) & Assistant Professor Faculty of Civil Engineering SCET, Surat For the Students of Civil Engineering
  2. 2. ...KEEP TAKING NOTES... Outline  Remote Sensing Defined  Resolution  Electromagnetic Energy (EMR)  Types  Interpretation  Applications
  3. 3. ...KEEP TAKING NOTES... Remote Sensing Defined  Remote Sensing is:  “The art and science of obtaining information about an object without being in direct contact with the object” (Jensen 2000).  There is a medium of transmission involved.
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  6. 6. ...KEEP TAKING NOTES... Remote Sensing Defined  Environmental Remote Sensing:  … the collection of information about Earth surfaces and phenomena using sensors not in physical contact with the surfaces and phenomena of interest.  We will focus on data collected from an overhead perspective via transmission of Electromagnetic Radiation.
  7. 7. ...KEEP TAKING NOTES... Remote Sensing Defined  Remote Sensing Includes:  A) The mission plan and choice of sensors;  B) The reception, recording, and processing of the signal data; and  C) The analysis of the resultant data.
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  11. 11. Orbits  Low Earth orbit (LEO): geocentric orbits with altitudes from 160 to 2,000 km (100–1,240 miles).  Medium Earth orbit (MEO): geocentric orbits ranging in altitude from 2,000 km (1,240 miles) to just below geosynchronous orbit at 35,786 kilometers (22,236 mi). ...KEEP TAKING NOTES... https://en.wikipedia.org/wiki/List_of_orbits
  12. 12. ...KEEP TAKING NOTES... When a satellite reaches exactly 42,164 kilometers from the center of the Earth (about 36,000 kilometers from Earth's surface), it enters a sort of “sweet spot” in which its orbit matches Earth's rotation.
  13. 13. ...KEEP TAKING NOTES... A satellites orbit the Earth in one of two basic types of orbit. •Circular satellite orbit: For a circular orbit, the distance from the Earth remains the same at all times. •Elliptical satellite orbit: The elliptical orbit changes the distance to the Earth •Geocentre: When satellites orbit the Earth, either in a circular or elliptical orbit, the satellite orbit forms a plane that passes through the centre of gravity or geocentre of the Earth. Source: http://www.radio- electronics.com/info/satellite/satellit e-orbits/satellites-orbit- definitions.php
  14. 14. ...KEEP TAKING NOTES...
  15. 15. ...KEEP TAKING NOTES... Energy Source or Illumination (A) Radiation and the Atmosphere (B) Interaction with the Target (C) Recording of Energy by the Sensor (D) Transmission, Reception, and Processing (E) Interpretation and Analysis (F) Application (G) Source: Canadian Centre for Remote Sensing Remote Sensing Process Components / Principle of RS
  16. 16. ...KEEP TAKING NOTES... Resolution  All remote sensing systems have four types of resolution:  Spatial  Spectral  Temporal  Radiometric
  17. 17. ...KEEP TAKING NOTES... High vs. Low? Spatial Resolution Source: Jensen (2000)
  18. 18. ...KEEP TAKING NOTES... Source: Jensen (2000) Spectral Resolution
  19. 19. ...KEEP TAKING NOTES... Temporal Resolution Time July 1 July 12 July 23 August 3 11 days 16 days July 2 July 18 August 3
  20. 20. ...KEEP TAKING NOTES... Radiometric Resolution 6-bit range 0 63 8-bit range 0 255 0 10-bit range 1023 Every time an image is acquired on film or by a sensor, its sensitivity to the magnitude of the electromagnetic energy determines the radiometric resolution. The radiometric resolution of an imaging system describes its ability to discriminate very slight differences in energy. The finer the radiometric resolution of a sensor, the more sensitive it is to detecting small differences in reflected or emitted energy. Source: http://www.nrcan.gc.ca/node/9379#answer
  21. 21. Radiometric Resolution  Imagery data are represented by positive digital numbers which vary from 0 to (one less than) a selected power of 2.  This range corresponds to the number of bits used for coding numbers in binary format. Each bit records an exponent of power 2 (e.g. 1 bit=2 1=2).  The maximum number of brightness levels available depends on the number of bits used in representing the energy recorded.  Thus, if a sensor used 8 bits to record the data, there would be 28=256 digital values available, ranging from 0 to 255. ...KEEP TAKING NOTES...
  22. 22. Whiz Quiz  Suppose you have a digital image which has a radiometric resolution of 6 bits. What is the maximum value of the digital number which could be represented in that image? ...KEEP TAKING NOTES...
  23. 23. Answer ...KEEP TAKING NOTES...
  24. 24. Answer ...KEEP TAKING NOTES... The number of digital values possible in an image is equal to the number two (2 - for binary codings in a computer) raised to the exponent of the number of bits in the image (i.e. 2# of bits). The number of values in a 6-bit image would be equal to 26 = 2 x 2 x 2 x 2 x 2 x 2 = 64. Since the range of values displayed in a digital image normally starts at zero (0), in order to have 64 values, the maximum value possible would be 63.
  25. 25. ...KEEP TAKING NOTES... Electromagnetic Radiation
  26. 26. ...KEEP TAKING NOTES... Electromagnetic Spectrum
  27. 27. ...KEEP TAKING NOTES... Signature Spectra
  28. 28. ...KEEP TAKING NOTES... Types of Remote Sensing  Aerial Photography  Multispectral  Active and Passive Microwave and LIDAR
  29. 29. ...KEEP TAKING NOTES... Aerial Photos  Balloon photography (1858)  Pigeon cameras (1903)  Kite photography (1890)  Aircraft (WWI and WWII)  Space (1947) Images: Jensen (2000)
  30. 30. ...KEEP TAKING NOTES...
  31. 31. ...KEEP TAKING NOTES... Multispectral  NOAA-AVHRR (1100 m)  GOES (700 m)  MODIS (250, 500, 1000 m)  Landsat TM and ETM (30 – 60 m)  SPOT (10 – 20 m)  IKONOS (4, 1 m)  Quickbird (0.6 m)
  32. 32. ...KEEP TAKING NOTES... AVHRR (Advanced Very High Resolution Radiometer) NASA NOAA National Oceanic and Atmospheric Administration
  33. 33. ...KEEP TAKING NOTES... GOES (Geostationary Operational Environmental Satellites) IR 4
  34. 34. ...KEEP TAKING NOTES... MODIS (250 m) (Moderate Resolution Imaging Spectro-radiometer)
  35. 35. ...KEEP TAKING NOTES... Landsat TM (False Color Composite)
  36. 36. ...KEEP TAKING NOTES... SPOT (2.5 m)
  37. 37. ...KEEP TAKING NOTES... QUICKBIRD (0.6 m)
  38. 38. ...KEEP TAKING NOTES... IKONOS (4 m Multispectral)
  39. 39. ...KEEP TAKING NOTES... IKONOS (1 m Panchromatic)
  40. 40. ...KEEP TAKING NOTES... RADAR (Radio Detection and Ranging) Image: NASA 2005
  41. 41. ...KEEP TAKING NOTES... LIDAR (Light Detection and Ranging) Image: Bainbridge Island, WA courtesy Pudget Sound LIDAR Consortium, 2005
  42. 42. ...KEEP TAKING NOTES... Elements of Image Interpretation  Shape:  Many natural and human-made features have unique shapes.  Often used are adjectives like linear, curvilinear, circular, elliptical, radial, square, rectangular, triangular, hexagonal, star, elongated, and amorphous.
  43. 43. ...KEEP TAKING NOTES... Jensen (2000) Shape
  44. 44. ...KEEP TAKING NOTES... Elements of Image Interpretation  Shadow:  Shadow reduction is of concern in remote sensing because shadows tend to obscure objects that might otherwise be detected.  However, the shadow cast by an object may be the only real clue to its identity.  Shadows can also provide information on the height of an object either qualitatively or quantitatively.
  45. 45. ...KEEP TAKING NOTES... Jensen (2000) Shadow
  46. 46. ...KEEP TAKING NOTES... Elements of Image Interpretation  Tone and Color:  A band of EMR recorded by a remote sensing instrument can be displayed on an image in shades of gray ranging from black to white.  These shades are called “tones”, and can be qualitatively referred to as dark, light, or intermediate (humans can see 40-50 tones).  Tone is related to the amount of light reflected from the scene in a specific wavelength interval (band).
  47. 47. ...KEEP TAKING NOTES... Jensen (2000) Tone and Color
  48. 48. ...KEEP TAKING NOTES... Elements of Image Interpretation  Texture:  Texture refers to the arrangement of tone or color in an image.  Useful because Earth features that exhibit similar tones often exhibit different textures.  Adjectives include smooth (uniform, homogeneous), intermediate, and rough (coarse, heterogeneous).
  49. 49. ...KEEP TAKING NOTES... Jensen (2000) Texture
  50. 50. ...KEEP TAKING NOTES... Elements of Image Interpretation  Pattern:  Pattern is the spatial arrangement of objects on the landscape.  General descriptions include random and systematic; natural and human-made.  More specific descriptions include circular, oval, curvilinear, linear, radiating, rectangular, etc.
  51. 51. ...KEEP TAKING NOTES... Jensen (2000) Pattern
  52. 52. ...KEEP TAKING NOTES... Elements of Image Interpretation  Height and Depth:  As discussed, shadows can often offer clues to the height of objects.  In turn, relative heights can be used to interpret objects.  In a similar fashion, relative depths can often be interpreted.  Descriptions include tall, intermediate, and short; deep, intermediate, and shallow.
  53. 53. ...KEEP TAKING NOTES... Height and Depth
  54. 54. ...KEEP TAKING NOTES... Elements of Image Interpretation  Association:  This is very important when trying to interpret an object or activity. Association refers to the fact that certain features and activities are almost always related to the presence of certain other features and activities.
  55. 55. ...KEEP TAKING NOTES... Jensen (2000) Association
  56. 56. ...KEEP TAKING NOTES...
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  58. 58. ...KEEP TAKING NOTES... Imaging Tools and Data  Google Earth  USGS Data  Bhuvan (of ISRO)
  59. 59. GIS OVERVIEW
  60. 60. A Model…  A model is simply a means of representing “reality” and, spatial data models provide abstraction of spatially referenced features in the real world.  Representation of real world is often divided into,  (1) Entities (distinct objects like points, locations, roads, admin boundaries)  (2) Fields (convey the idea of values of some property at all locations)  Objects that are well described as distinct entities are sensibly represented using the VECTOR DATA MODEL.  Properties that tend to vary quite smoothly from place to place are frequently represented using RASTER DATA MODEL.  Exceptions are isolines / contours / temperature elevation etc… ....KEEP TAKING NOTES.... 60
  61. 61. What is GIS?  Geographic Information Systems (GIS) are computerized systems designed for the storage, retrieval and analysis of geographically referenced data  GIS uses advanced analytical tools to explore at a scientific level the spatial relationships, patterns, and processes of cultural, biological, demographic, economic, geographic, and physical phenomena 61....KEEP TAKING NOTES....
  62. 62. Tools for GIS  Hardware  Computer  Digitizer  Scanner  Printer/Plotter  Software  Desktop GIS  Internet GIS  CAD Software  Database Software  Multimedia (photos, videos, 3D models) 62....KEEP TAKING NOTES....
  63. 63. Unique capabilities of GIS  GIS stores related geographic features in separate collections of files called map layers  Map layers can be reused easily and assembled into any number of map compositions and overlaid for analysis 63....KEEP TAKING NOTES....
  64. 64. GIS answers the following  Location: What is at...? Where is it?  Condition: Status of features?  Trends: What has changed since...?  Patterns: What spatial patterns exist?  Modeling: What if…? 64....KEEP TAKING NOTES....
  65. 65. Scale of GIS data Global to local 65....KEEP TAKING NOTES....
  66. 66. Vector data Map features  Vector data comprise Points (x & y) , lines (segment of arcs), polygons (lines with same start & end points)  Data comprise explicit spatial coordinates  Feature attributes  Every feature has attributes (e.g. name, area, population) Shape Name Class Pop2000 State Point New York City 8,008,278 NY Point Los Angeles City 3,694,820 CA Point Chicago City 2,896,016 IL 66....KEEP TAKING NOTES.... Vector data is also called ‘spaghetti’ data
  67. 67. Vector data  Line feature comprises of two forms of point locations (vertices), which represent change in direction of ARCS…  NODES which represent the start & end of arcs, including locations where different arcs connect…  Vector data are divided into their SPATIAL component and ATTRIBUTE component. Attribute linked to each spatial feature are stored using RELATIONAL DATABASE SYSTEM. ....KEEP TAKING NOTES.... 67
  68. 68. Raster Data Stored electronic image or picture taken as an aerial photograph or satellite image Composed of a rectangular array of square cells, called pixels, with a number in each cell representing the solid color fill of that cell… Raster grids are conceptually simple structures, comprising square cells with numeric values or classes attached to each cell.. 68....KEEP TAKING NOTES....
  69. 69. ....KEEP TAKING NOTES.... 69
  70. 70. ....KEEP TAKING NOTES.... 70
  71. 71. TOPOLOGY  Topology can be defined as “The mathematical study of objects which are preserved through deformation, twistings and stretchings.”  Operations concerned with connections between objects are dependent on information about topological relationships. ....KEEP TAKING NOTES.... 71
  72. 72. Topology ...KEEP TAKING NOTES...
  73. 73. GIS DATA AND LAYERS
  74. 74. GIS example  Identify polluting companies and their proximity to populations in poverty, water features, or schools.  Start with Databases Map layers 74....KEEP TAKING NOTES....
  75. 75. Databases Not easy to interpret 75....KEEP TAKING NOTES....
  76. 76. Data shown as GIS layers 76....KEEP TAKING NOTES....
  77. 77. Additional layers Political features (municipalities) 77....KEEP TAKING NOTES....
  78. 78. Additional layers Physical features (lakes, rivers, etc.) 78....KEEP TAKING NOTES....
  79. 79. Additional layers Administrative data (schools) 79....KEEP TAKING NOTES....
  80. 80. Maps and tables are interactive Identify features 80....KEEP TAKING NOTES....
  81. 81. Maps and tables are interactive Select features 81....KEEP TAKING NOTES....
  82. 82. Advanced GIS functions Proximity selections 82....KEEP TAKING NOTES....
  83. 83. Advanced GIS functions  Buffers  Select top polluting companies and show the number of schools within 2 miles of these companies. 83....KEEP TAKING NOTES....
  84. 84. GIS APPLICATIONS AND EXAMPLES
  85. 85. GIS applications Engineering Civil engineering, surveying, property mapping Business Site location, delivery systems, marketing, media and press, real estate. Defense/intelligen ce Military operations, geospatial intelligence Government Federal, state, local, economic development, elections, urban and regional planning. Health Public health, health and human services, hospitals, managed care, research. Natural resources Agriculture, archaeology, climate change, conservation, environmental management, forestry, marine and coast, mining, petroleum, water resources. Public safety Computer-Aided Dispatch, emergency/disaster management, EMS, homeland security, law enforcement, fire protection, wildfire management Transportation Aviation, highways, logistics, railways, ports and maritime, public transit Utilities/communic ations Electric, gas, pipeline, telecommunications, water/wastewater 85....KEEP TAKING NOTES....
  86. 86. Thanks Prof. Bhasker V. Bhatt www.bvbhatt.com +91-98258-35364 bhasker.bhatt@scet.ac.in Content source credit courtesy is due, where not mentioned in specific: Remote Sensing by Gregory Vandeberg; Dept. of Geography, University of North Dakota, USA (Content created 21/10/2005) and GIS Tutorial 1 - Basic Workbook by Jay Loteria; Anne Connell (Content created 06/03/2010)

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