geoinformatics(nce 402)

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  1. 1. GEOINFORMATICS(NCE 402) By- Md Mozaffar Masud Assistant Professor Civil Engineering Department JIT, Barabanki
  2. 2. UNIT 1
  3. 3. INTRODUCTION Aerial photography is defined as art of taking photograph from a point in the air for the purpose of making study on earth surface. Aerial photography and its planning includes selection of types of aero plane and camera, film and filter combination which is of great importance in photo interpretation. Most of the conventional aerial photography is done at 1:30000 to 1:60000 scale on a conventional black and white panchromatic film.
  4. 4. INTRODUCTION For more specific and detailed information such as ground water surveys, land use planning , mineral exploration, photographs of scale 1:10000 to 1:15000 are most suitable. Quality of photographs depend upon- flight and weather condition Camera lens Film and filters Developing and printing processes
  5. 5. Basic Terminology Focal Length the distance between the camera lens and the film Flying Height the height of the plane (and therefore the camera) above the ground Nadir the point on the ground directly below the camera Flight Line the path of the airplane over which a sequence of pictures is taken Stereoscope - a device used to view/measure feature heights and/or landscape elevations using pairs of air photographs Fiducial Marks marks on photographs used to align adjacent photos for stereoscopic analysis
  6. 6. Scale of photographs
  7. 7. Air Photo Scale Scale (RF) = [1 : (flying height / focal length)] or (focal length/flying height) Focal length and flying height should be in the same units Example: Focal length = 6 inches or 0.5 ft Flying height = 10,000 ft Scale = 0.5 / 10,000 = 1:20,000
  8. 8. Basic Camera Everything above C is inside the camera The film sits on the film plane f = focal length H = Elevation above ground ACB = angle of coverage Scale: RF = 1:(H / f)
  9. 9. Types of vantage points to acquire photographs Vertical vantage points Low-oblique vantage points High-oblique vantage points
  10. 10. Vertical Aerial Photography San Juan River
  11. 11. Low-oblique Aerial Photography Bridge on the Congaree river near Columbia
  12. 12. High-oblique Aerial Photography Grand Coulee Dam in Washington
  13. 13. Types of film Black and White most often used in photogrammetry cheap Color easy to interpret fuzzy due to atmospheric scattering Infrared Color Infrared (CIR)
  14. 14. CIR and True Color Film Type Examples CIR True Color
  15. 15. CIR Films
  16. 16. Stereoscopic Parallax Stereoscopic Parallax is caused by a shift in the position of observation Parallax is directly related to the elevation / height of features Vertical stereo pairs of aerial photographs are used to take 3-D measurements by measuring parallax
  17. 17. Stereoscope
  18. 18. Sources of Distortion From Collection: Yaw plane fuselage not parallel to flight line Think about having to steer your car slightly into a strong cross wind Leads to pictures not being square with the flight-line Pitch nose or tail higher than the other Leads to principal point not being at nadir Roll one wing higher than the other Leads to principal point not being at nadir Natural: Haze Topographic changes For example, if flying over mountains, the height above the ground will a) change from picture to picture, and b) not be uniform in a single picture. Both of these lead to irregularities in the photo scale
  19. 19. Photo interpretation: Recognition Elements Shape Size Color/Tone Texture Pattern Site Association Shadow
  20. 20. Photo interpretation: Recognition Elements Shape cultural features - geometric, distinct boundaries natural features - irregular shapes and boundaries Shape helps us distinguish old vs. new subdivisions, some tree species, athletic fields, etc. The pentagon Meandering river in Alaska Interior Alaskan village (note airstrip near top of image)
  21. 21. Size relative size is an important clue big, wide river vs. smaller river or slough apartments vs. houses single lane road vs. multilane Photo interpretation: Recognition Elements
  22. 22. Photo interpretation: Recognition Elements Color/Tone coniferous vs. deciduous trees CIR - Spruce forest (black) with some deciduous (red) trees. CIR Deciduous (leafy) vegetation (red). CIR- Mixed spruce And deciduous forest on hillside with tundra in valley bottom
  23. 23. Photo interpretation: Recognition Elements Texture coarseness/smoothness caused by variability or uniformity of image tone or color smoothness tundra, swamps, fields, water, etc. coarseness - forest, lava flows, mountains etc. CIR- Marshy tundra with many small ponds CIR - Bare rounded Mountains (blue) surrounded by tundra and lakes CIR - Tundra showing drainage pattern
  24. 24. Photo interpretation: Recognition Elements Pattern overall spatial form of related features repeating patterns tend to indicate cultural features - random = natural drainage patterns can help geologists determine bedrock type A dendritic pattern is characteristic of flat- lying sedimentary bedrock
  25. 25. Photo interpretation: Recognition Elements Site site - relationship of a feature to its environment differences in vegetation based on location: In interior Alaska, black spruce dominant on the north side of hills and deciduous trees on the south side. Vegetation is often has different characteristics by rivers than away from them Meandering Alaskan river Interior Alaskan hillside
  26. 26. Photo interpretation: Recognition Elements Association identifying one feature can help identify another - correlation The white cloud and black shadow have the same shape, they are related The long straight airstrip near the top of the image indicates that there might be a village or settlement nearby
  27. 27. Photo interpretation: Recognition Elements Shadows shadows cast by some features can aid in their identification some tree types, storage tanks, bridges can be identified in this way shadows can accentuate terrain The mountain ridge on the right side of this image is accentuated by shadow
  28. 28. UNIT 2
  29. 29. What is remote sensing used for What is reRemote Sensingmote sensing used for What is remote sensing used for Definitions: The acquisition of physical data of an object without touch or contact . The observation of a target by a device some distance away. The use of electromagnetic radiation sensors to record images of the environment, which can be interpreted to yield useful information.
  30. 30. Advantages of RS 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. Remote sensing can be either passive or active. Active systems have their own source of energy whereas the passive systems depend upon the solar illumination or self emission for remote sensing
  31. 31. Elements of RS
  32. 32. Process of RS Data Emission of electromagnetic radiation, or EMR (sun/self- emission) Transmission of energy from the source to the surface of the earth, as well as absorption and scattering Interaction of EMR with the earth's surface: reflection and emission Transmission of energy from the surface to the remote sensor Sensor data output Data transmission, processing and analysis
  33. 33. Remotely Sensed Data
  34. 34. Remote Sensing Satellite Polar-Orbiting Satellites A polar orbit is a satellite which is located near to above of poles. This satellite mostly uses for earth observation by time.
  35. 35. Remote Sensing Satellite Geostationary Satellites A geostationary satellite is one of the satellites which is getting remote sense data and located satellite at an altitude of approximately 36000 kilometres and directly over the equator
  36. 36. Remote Sensing Sensors Sensor is a device that gathers energy (EMR or other), converts it into a signal and presents it in a form suitable for obtaining information about the target under investigation. These may be active or passive depending on the source of energy . Sensors used for remote sensing can be broadly classified as those operating in Optical Infrared (OIR) region and those operating in the microwave region. OIR and microwave sensors can further be subdivided into passive and active.
  37. 37. Active sensors use their own source of energy. Earth surface is illuminated through energy emitted by its own source, a part of its reflected by the surface in the direction of the sensor is received to gather information. Passive sensors receive solar electromagnetic energy reflected from the surface or energy emitted by the surface itself. These sensors do not have their own source of energy and can not be used at night time, except thermal sensors. Again, sensors (active or passive) could either be imaging, like camera, or Sensor which acquire images of the area and non-imaging types like non-scanning radiometer or atmospheric sounders.
  38. 38. Resolution Resolution is defined as the ability of the system to render the information at the smallest discretely separable quantity in terms of distance (spatial), wavelength band of EMR (spectral), time (temporal) and/or radiation quantity (radiometric)
  39. 39. Types of Resolution Spatial resolution Spectral Resolution Radiometric Resolution Temporal Resolution
  40. 40. Spatial resolution The earth surface area covered by a pixel of an image is known as spatial resolution Large area covered by a pixel means low spatial resolution and vice versa
  41. 41. Spatial resolution
  42. 42. Spectral Resolution Is the ability