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Remote Sensing Data Acquisition

Remote Sensing Data Acquisition. 1. Major Remote Sensing Systems. Major Remote Sensing Systems. Aerial photography Electro-Optical remote sensing Microwave remote sensing Close range remote sensing. Aerial Photography. Detector Process Vehicle Products: aerial photographs.

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Remote Sensing Data Acquisition

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  1. Remote SensingData Acquisition

  2. 1. Major Remote Sensing Systems

  3. Major Remote Sensing Systems • Aerial photography • Electro-Optical remote sensing • Microwave remote sensing • Close range remote sensing

  4. Aerial Photography • Detector • Process • Vehicle • Products: aerial photographs

  5. http://nationalmap.gov/viewer.html • http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm

  6. Electro-Optical Remote Sensing • Detector • Process • Vehicle • Products: Digital images

  7. Buffalo, NY November 20, 2000 http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=4396

  8. Biloxi Coast–Before Hurricane Katrina, April 12, 2005 Biloxi Coast–After Hurricane Katrina, August 31, 2005. http://www.esri.com/news/pressroom/hurricanemaps.html

  9. Microwave Remote Sensing • Uses antennas as detectors • Passive microwave systems • Active microwave systems, RADAR

  10. http://rst.gsfc.nasa.gov/Sect8/Sect8_3.html http://www.erh.noaa.gov/buf/

  11. Close Range Remote Sensing

  12. Visual interpretation vs. digital image processing

  13. 2. Resolutions • Spectral resolution • Radiometric resolution • Spatial resolution • Temporal resolution

  14. French SPOT French SPOT French SPOT Landsat 7 Landsat7 Landsat 7 DS DS - - 1260 1260 DS - 1260 AVIRIS AVIRIS AVIRIS 2.0 m m 1.0 1.0 1.0 m m m m m 2.0 2.0 m m m m m Spectral Resolutions

  15. Spectral Resolutions • The dimension and the number of specific wavelength intervals in the EM spectrum to which a sensor is sensitive, e.g. B, G, R NIR bands Green Red Near Infrared NIR http://rst.gsfc.nasa.gov/Intro/Part2_17.html

  16. Radiometric Resolution • The sensitivity of a detector to differences in signal strength as it records the radiant flux reflected or emitted from the terrain 8 bit 4 bit 2 bit 1 bit 256 levels 16 levels 4 levels 2 levels

  17. Spatial Resolution • A measure of the smallest angular or linear separation between two objects that can be resolved by the sensor, 30m, 1m, 1km 10m 20m 40m 80m

  18. Temporal Resolution • How often a given sensor obtains imagery of a particular area, e.g., 16 days, daily

  19. Pixels and IFOV • Pixel - picture element • IFOV - Instantaneous Field of View the ground area viewed by the sensor at a given instant

  20. 3. Color Theory • Additive primaries • Subtractive primaries

  21. Additive Primaries • blue, green, and red  superimposing blue, green, and red light: blue  + green + red = white      green + red  = yellow      green + blue = cyan      red   + blue = magenta

  22. Color Theory • Yellow, magenta, and cyan are complements of blue, green, and red, respectively •  Various combinations of the three primaries produce different colors

  23. Subtractive Primaries • yellow, magenta, and cyan each absorbs its complementary color from white light           yellow  = white - blue           magenta = white - green           cyan = white - red

  24. Subtractive Primaries • Superimposing yellow, magenta, and cyan dye:       yellow  + magenta + cyan = black        yellow  + magenta = red        yellow  + cyan = green        magenta + cyan = blue

  25. True and False Color Images

  26. True and False Color Images http://www.crisp.nus.edu.sg/~research/tutorial/opt_int.htm

  27. Readings Chpt 2.7

  28. 4. Introduction of Satellite Systems • Land observation satellite systems         vehicles - spacecraft         devices - electro-optical sensors         images - digital images         target - earth resources

  29. Satellite Systems • Advantages vs. aerial photography provide a synoptic view systematic, repetitive coverage multiple spectral information digital format for quantitative analysis less expensive

  30. History of Satellite Systems • Landsat (Land Satellite) system  - launched in 1972  - first satellite for observation of the earth's land areas  - important in earth resources studies and a model for later satellite systems

  31. History of Satellite Systems • Early Landsat (1,2,3) was named Earth Resources Technology Satellite (ERTS) and designated by a letter, i.e. A,B,C, renamed later as Landsat 1, 2, 3 • Early Landsat applied spectrums used in aerial photography but at a satellite altitude • Early Landsat carried Return Beam Vidicon (RBV) and Multispectral Scanner (MSS) sensor systems • New generation of Landsat (4,5,7) carries MSS and Thematic Mapper (TM) and other more sophisticated sensor systems

  32. Satellite Orbits • Geosynchronous orbits • Sun-synchronous orbits • Inclination • Ascending and descending nodes   

  33. Geosynchronous Orbits • Revolve at an angular rate that matches the earth's rotation • Weather satellites, communication satellites • Views the full range of variation of solar illumination http://www.crisp.nus.edu.sg/~research/tutorial/spacebrn.htm

  34. Sun-Synchroneous Orbits • Maintain a constant angular relationship with the solar beam, the satellite will always pass overhead at the same local time for similar illumination and shadowing conditions http://www.crisp.nus.edu.sg/~research/tutorial/spacebrn.htm http://www.youtube.com/watch?v=LttI1IofXRI

  35. Satellite Orbits • Inclination the angle between the orbital plane and the equatorial plane • Coverage of the earth's surface http://www.atmos.umd.edu/~owen/CHPI/IMAGES/orbitss.html

  36. Satellite Orbits • Descending node  - the point the satellite crosses equator on southward track •  Ascending node  - the point the satellite crosses equator on northward track http://www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/fundam/chapter2/chapter2_2_e.html

  37. Satellite Orbits • Most satellites cross over the equator at about 9:30am, an optimal time with respect to sun angle and cloud cover

  38. Readings • Chapter 6

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