Satellite Mapping


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Satellite Mapping

  1. 1. Notes on Ch. 9 & 10Satellite Mapping of Earth Resources and Earth’s Atmosphere and Water Resources<br />1<br />
  2. 2. Natural resource analysis has never had a high priority in satellite funding.<br />Highest priorities: Defense, National Security, Communications, Commercial, Weather.<br />A great deal of analysis has been done with limited resources.<br />The CIA and Pentagon have the best toys.<br />2<br />Some Remarks<br />
  3. 3. Started in 1972.<br />First called ERTS (Earth Resource Technology Satellite) Figure 9-1 Landsat vehicles.<br />System designed to follow a specific orbit that would bring it back over the same locus on the Earth’s surface, thereby providing repetitive coverage to monitor change through time. See Figure 9-2.<br />Returns to a specific location every 18 days.<br />3<br />Landsat<br />
  4. 4. Primary tool of Landsat.<br />Records reflected and/or radiated energy from the Earth simultaneously in four contiguous bands of the EMS.<br />Provides multiple data sets to produce geographically registered images (one for each band).<br />Each scene covers 115 miles by 115 miles (185km) in the shape of a parallelogram. <br />Overlap provided between scenes.<br />4<br />Multispectral Scanning System (MSS)<br />
  5. 5. Differences in the bands sensed between the different LandsatS. See Figure 9-3.<br />The bands on the MSS can be selected to give the same results as Color Infrared Film (CIR)<br />5<br />MSS (continued)<br />
  6. 6. Picture element.<br />The smallest area on the ground that is detected by a sensor.<br />A general measure of the sensitivity of a digital scanner<br />The MSS on the first three Landsats could detect a minimum of 79 sq. meters. The value recorded is the average reflectance for the pixel.<br />6<br />Pixel<br />
  7. 7. This is a fairly coarse density.<br />To see an object on MSS it should normal be about twice the width of a pixel. Objects with great contrast can be seen at single pixel density.<br />MSS data needs extensive processing to create a useful image.<br />7<br />Pixel (continued)<br />
  8. 8. Starting on Landsat 4 a new scanner.<br />Offered increased ground resolution, a greater number of spectral bands, and faster return time to image a particular Earth surface location (16 days vs. 18)<br />Spectral bands modified to improve detection of soil, rock , and vegetation.<br />Ground resolution improved to 30meters<br />8<br />Thematic Mapper (TM)<br />
  9. 9. Assigning the reflectance values of data from sensed bands to the standard red, green, and blue layers of color film using filters.<br />A common technique with satellite data.<br />9<br />False Color Images<br />
  10. 10. A European (French) natural resource satellite<br />Système Pour L’Observation de la Terre<br />Started in 1977. SPOT 1 launched in 1986.<br />First big job: acquiring images of the Chernobyl accident in the Soviet Union in May.<br />10<br />SPOT<br />
  11. 11. Orbital path similar to Landsat. Sunsynchronous (passing over the same latitude at the same local time). Required 26 days to return to the same location.<br />Has higher resolution than Landsat, but the area of one scene is much smaller.<br />11<br />SPOT (continued)<br />
  12. 12. Panchromatic: 0.5 to 0.73 micrometers. See EMS on Fig. 3-1. Ground resolution of 10m squared.<br />Multispectral: 0.5-0.59 green, 0.61 to 0.68 red, and 0.79 to 0.89 micrometers IR. Pixel resolution 20m squared.<br />Adjustable viewing angle 27o east or west of the orbital path. Allows for the creation of stereo pairs.<br />12<br />Sensors on SPOT<br />
  13. 13. Large format camera on Space Shuttle. Multi-camera system to provide cartographic quality images. Can exactly locate position on earth’s surface and the nadir of the image.<br />Shuttle hand-held photography.<br />Advantages and Disadvantages of imagery from manned flights???<br />13<br />NASA Manned Flight Images<br />
  14. 14.<br />Landsat program home page:<br />SPOT<br />14<br />Web Links<br />
  15. 15. Weather forecasting. (fire fighting)<br />Climate changes<br />Pollution and particulate matter.<br />Figure 10-1 and 2. Satellites and sensing tools.<br />15<br />Satelite mapping of Earth’s Atmosphere and Water Resources<br />
  16. 16. Most of these satellites focus on the visible, reflected IR, and thermal IR portions of the EMS. Fig. 10-3 shows the transmission windows.<br />Types of operational satellites (Figure 10-4):<br />Polar orbiters- follows path roughly parallel to the earth’s axis from pole to pole.<br />Geostationary – orbit and speed that positions them above any point on the Earth where they maintain position constantly<br />16<br />Spectral Bands Utilized<br />
  17. 17. Known by acronym GOES – Geostationary Operational Environmental Satellite. Several in service since 1975<br />Day-night capability. Sensor is VISSR – Visible-Infrared Spin-Scan Radiometer). Records energy in:<br />One visible band: 0.55 – 0.70 microns<br />Thermal IR 10.5 – 12.5 microns<br />17<br />Geostationary Weather Satellites <br />
  18. 18. Figure 10-7 full disc visible image of part of the earth and its cloud cover<br />All clouds at any elevation show up in this image. <br />Allows nephanalysis – the study of cloud patterns and formations.<br />18<br />GOES continued<br />
  19. 19. Figure 10-8 full disc infrared image.<br />Images have geographic grid of meridians and parallels and continent and political boundaries<br />Full disc IR shows thermal values for land, water, and clouds.<br />Polarity of gray tones shows warmer temperatures as dark and colder temperatures as light. <br />Coldest, highest clouds are white. Lower clouds dark. Most unstable clouds most visible.<br />19<br />GOES continued<br />
  20. 20. The visible and thermal IR images combined give good cloud information. Can be compared day to day.<br />Comparing areas with or devoid of clouds can show high pressure and low pressure areas.<br />Water vapor imagery. Uses energy radiated in the 6.7 micron band. At this wavelength the radiation is absorbed and reradiated by water in the gaseous state.<br />GOES satellite viewer:<br />NOAA Weather forecast for Mont Alto, PA<br />20<br />GOES continued<br />
  21. 21. Numerous satellites and scanners have been used to sense environmental data since 1060<br />NESDIS<br />Some of the products include:<br />Temperature soundings in the atmosphere<br />Ice analysis in the polar regions and Great Lakes<br />Vegetation index <br />Snow cover <br />Tropical cyclones<br />Wildfires<br />21<br />Polar Orbiter Satellites<br />