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Chapter 6

Chapter 6. Earth resource satellites operating in the optical spectrum Introduction to Remote Sensing Instructor: Dr. Cheng-Chien Liu Department of Earth Sciences National Cheng-Kung University Last updated: 28 May 2003. 6.1 Introduction.

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Chapter 6

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  1. Chapter 6 Earth resource satellites operating in the optical spectrum Introduction to Remote Sensing Instructor: Dr. Cheng-Chien Liu Department of Earth Sciences National Cheng-Kung University Last updated: 28May 2003

  2. 6.1 Introduction • Remote sensing + space exploration (RS+SE) interest and application over a wider range of disciplines • Current application • New technology  new or improved satellite/sensor  new application • The most important outcome of RS+SE  observing earth  earth system

  3. 6.1 Introduction (cont.) • This chapter  optical range  0.3 m m~14 m m • Landsat • Spot • NOAA series

  4. 6.2 Early history of space imaging • Ludwig Bahrmann (1891): New or improved apparatus for obtaining Bird’s eye photographic views • Alfred Maul (1907): gyrostabilization • Alfred Maul (1912): 41kg, 200mm x 250 mm, 790m • 1946~1950: V2 rockets • 1960~ : TIROS-1, early weather satellite • Not just look at but also look through

  5. 6.2 Early history of space imaging (cont.) • 1960s: Mercury, Gemini, Apollo • Alan Shepard, 1961, 70 mm, 150 photos • John Glenn, 1962, 35 mm, 48 photos. • Later Mercury missions: 70 mm, 80 mm • Gemini GT-4 mission: formal experiment directed at geology • Tectonics, volcanology, geomophology. • 1:2,400 1100 photos • Apollo 9: 4 camera array, electrically triggered. 140 sets of imagery

  6. 6.2 Early history of space imaging (cont.) • Skylab 1973 • Earth Resources Experiment Package (EREP) • 6-camera multi-spectral array • A long focal length “earth terrain” camera • A 13-channel multispectral scanner • A pointable spectroradiometer • Two microwave systems. • 35,000 images • U.S.-USSR Apollo-Soyuz Test Project (ASTP)

  7. 6.3 Landsat satellite program overview • Earth Resources Technology Satellite (ERTS) 1967 • ERTS-1, 1972~1978 • Nimbus weather satellite  modified • Experimental system  test feasibility • Open skies principle • Landsat-2, 1975 (ERTS-2)

  8. 6.3 Landsat satellite program overview (cont.) • Table 6.1: Characteristics of Landsat 1~6 • Return Beam Vidicon (RBV) camera systems • Multispectral Scanner system (MSS) • Thematic Mapper (TM) • Enhanced Thematic Mapper (ETM) • Table 6.2: Sensors used on Landsat 1~6 missions

  9. 6.4 Orbit characteristic of Landsat-1, -2, and –3 • Fig 6.1: Landsat –1, -2, and –3 observatory configuration • 3m x 1.5m, 4m width of solar panels, 815 kg, 900 km • Inclination = 90 • To= 103 min/orbit • Fig 6.2: Typical Landsat-1, -2 and –3 daily orbit pattern • Successive orbits are about 2760km • Swath: 185km • Orbital procession  18 days for coverage repetition 20 times of global coverage per year

  10. 6.4 Orbit characteristic of Landsat-1, -2, and –3 (cont.) • Sun-synchronous orbit • 9:42 am  early morning skies are generally clearer than later in the day • Pros: repeatable sun illumination conditions on the same day in every year • Cons: variable sun illumination conditions with different locations and seasons  variations in atmospheric conditions

  11. 6.5 Sensors onboard Landsat-1, -2 and –3 • 3-Channel RBV • 185km x 185 km • Ground resolution: 80m • Spectral bands: 1: 0.475 mm~0.575 mm (green) 2:0.580 mm~0.680 mm (red) 3: 0.690 mm~0.830 mm (NIR) • Expose  photosensitive surface  scan  video signal • Pros: • Greater cartographic fidelity • Reseau grid  geometric correction in the recording process

  12. 6.5 Sensors onboard Landsat-1, -2 and –3 (cont.) • 3-Channel RBV (cont.) • Landsat-1: malfunction  only 1690 scenes • Landsat-2  only for engineering evaluation  only occasionally RBV imagery was obtained. • Landsat-3 • Single broad band (0.505~0.75 u mm) • 2.6 times of resolution improved: 30m  double f • Two-camera side-by-side configuration with side-lap and end-lap. (Fig 6.4) • Fig 6.5: Landsat-3 RBV image

  13. 6.5 Sensors onboard Landsat-1, -2 and –3 (cont.) • 4 Channel MSS • 185km x 185km • Ground resolution: 79m • Spectral band: • Band 4: 0.5 mm ~ 0.6 mm (green) • Band 5: 0.6 mm ~ 0.7 mm (red) • Band 6: 0.7 mm ~ 0.8 mm (NIR) • Band 7: 0.8 mm ~ 0.9 mm (NIR) • Band 8: 10.4~12.6 um  Landsat-3, failed • Band 4~7  band 1~4 in Landsat-4, -5 • Fig 6.6: Comparison of spectral bands

  14. 6.5 Sensors onboard Landsat-1, -2 and –3 (cont.) • 4 Channel MSS (cont.) • Fig 6.7: Landsat MSS operating configuration • Small TFOV  use an oscillating scan mirror • A-to-D converter (6 bits) • Pixel width: 56m x 79m set by the pixel sampling rate (Fig 6.8) • Each Landsat MSS scene  185km x 185km • 2340 scan lines, 3240 pixels per line, 4 bands • Enormous data • Fig 6.9: Full-frame, band 5, Landsat MSS scene • Parallelogram  earth’s rotation • 15 steps • Tick marks  Lat. Long. • Annotation block • Color composite: band 4 (b), band 5 (g), band 7(r)(Fig 6.6)

  15. 6.5 Sensors onboard Landsat-1, -2 and –3 (cont.) • Data distribution • Experiment  transitional  operational • NASA NOAA NASA USGS EOSAT USGS Landsat-1,-2,-3 Landsat-4,-5,-6 Landsat-7 Department of Interior Department of Commerce Department of Defense • Data receiving station • Data reprocessing • Data catalogue

  16. 6.6 Landsat MSS image interpretation • Applications: • agriculture, botany cartography, civil engineering, environmental monitoring, forestry, geography, geology, geophysics, land resources analysis, land use planning, oceanography, water resource analysis • Comparison of Landsat & airborne image • Table 6.4 • Resolution • Coverage • Complementary not replacement • 2-D, non-stereo mode

  17. 6.6 Landsat MSS image interpretation (cont.) • Characteristics of MSS image • Effective resolution  79m, (30m for Landsat-3) but linear feature with sharp contrast can be seen • 1-D displacement relief (in E-W direction) • Limited area can be viewed in stereo  study topographic • High altitude + low TFOV  little RD  planimeter map • E.g. World Bank, USGS. DMA, petroleum company

  18. 6.6 Landsat MSS image interpretation (cont.) • Characteristics of MSS image (cont.) • Band 5 (red)  better atmospheric penetration  detecting cultural features • Band 4 (green)  deep, clear water penetration • Band 6, 7  lineating water bodies (dark) • The largest single use of Landsat MSS data  geologic studies  band 5.7

  19. 6.6 Landsat MSS image interpretation (cont.) • Fig 6.10 : four Landsat MSS bands • Extent of the urban area (B4, 5, light) • Major road (B4, 5 light, not B6, B7 dark) • Airport • Asphalt-surfaced runways • Four major lakes and connected river (B6, 7 dark) • mid-July  algae  green  B4: similar to the surrounding agricultural land • Agricultural field. (B5, 6, 7) • Forest (B4, 5 dark)  winter images are preferred

  20. 6.6 Landsat MSS image interpretation (cont.) • Fig 6.11: Landsat MSS band 5 • December image • 20 cm snow covered  all water bodies are frozen • Snow covered upland and valley floors  light tone • Steep, tree-covered valley sides  dark tone • September image • Identify forest area

  21. 6.6 Landsat MSS image interpretation (cont.) • A hit-or-miss proposition • Some events leave lingering trace • Fig 6.12: Landsat MSS band 7 • July image  200 m3/sec • March image  1300 m3/sec  once every four years • Fig 6.13: Mississippi River Delta • Silt flow but vague boundary  band 5 • Delineation of the boundary  band 7 • Fig 6.14: short-lived phenomena • Active forest fire in Alaska • Volcanic eruption on Kunashir Island

  22. 6.6 Landsat MSS image interpretation (cont.) • A hit-or-miss proposition (cont.) • Fig 6.15: Extensive geologic features visible on MSS • San Andreas fault, Six solid dots  earthquake > 6.0 • Fig 6.16: Landsat MSS band 6 • 66-km-wide Manicouagan ring  212-million-year-old meteorite impact crater • Fig 6.17: Landsat MSS images of Mt. St. Helens before and after its 1980 eruptions • Fig 6.18: Landsat MSS image of Maritoba, Canada, showing tornado and hail scar • Fig 6.19: Landsat MSS image of East kalimantan, Indonesia, showing tropical deforestation

  23. 6.7 Orbit characteristics of Landsat-4 and -5 • Fig 6.20: Sun-synchronous orbit of Landsat-4 and –5 • Altitude: 900  705km • Retrievable by the space shuttle • Ground resolutions • Inclination 98.20 T=99min  14.5 orbit/day • 9:45 am • Fig 6.21: adjacent orbit space = 2752km • 16-day repeat cycle • 8-day phase between Landsat-4 and –5 (Fig 6.22)

  24. 6.8 Sensors onboard Landsat-4 and -5 • Fig 6.23: Landsat-4 and –5 observatory configuration • MSS, TM • 2000 kg, 1.5x2.3m solar panels x 4 on one side • High gain antenna  Tracking and Data Relay Satellite system (TDRSS) • Direct transmission  X-band and S-band • MSS: 15 Mbps • TM: 85 Mbps

  25. 6.8 Sensors onboard Landsat-4 and –5 (cont.) • MSS • Same as previous except for larger TFOV for keeping the same ground resolution (79m  82m) • Renumber bands • TM • 7 bands (Table 6.4) • DN: 6  8 bits • Ground resolution: 30m (thermal band: 120m) • Geometric correction  Space Oblique Mercator (SOM) cartographic projection

  26. 6.8 Sensors onboard Landsat-4 and –5 (cont.) • TM (cont.) • Bi-directional scan  the rate of oscillation of mirror dwelling time  geometric integrity signal-to-noise • Detector: • MSS: 6x4=24 • TM: 16x6+4x1=100 • Fig 6.24: Thematic Mapper optical path and projection of IFOV on earth surface • Fig 6.25: Schematic of TM scan line correction process

  27. 6.9 Landsat TM Image interpretation • Pros: • Spectral and radiometric resolution • Ground resolution • Fig 6.26: MSS vs TM • Fig 6.27: All seven TM bands for a summertime image of an urban fringe area • Lake, river, ponds: b1,2 > b3 > b4=b5=b7=0 • Road urban streets: b4  min • Agricultural crops: b4  max • Golf courses

  28. 6.9 Landsat TM Image interpretation (cont.) • Fig 6.27 (cont.) • Glacial ice movement: upper right  lower left • Drumlins, scoured bedrock hills • Band 7  resample from 120m to 30m • Plate 12 + Table 6.5: TM band color combinations • (a): normal color  mapping of water sediment patterns • (b): color infrared  mapping urban features and vegetation types • (c)(d): false color

  29. 6.9 Landsat TM Image interpretation (cont.) • Fig 6.28: Landsat TM band 6 (thermal infrared) image • Correlation with field observations  6 gray levels  6T • Plate 13: color-composite Landsat TM image • Extremely hot  blackbody radiation  thermal infrared • TM bands 3, 4 and 7

  30. 6.9 Landsat TM Image interpretation (cont.) • Fig 6.29: Landsat TM band 5 (mid-infrared) image • Timber clear-cutting • Fig 6.30: Landsat TM band 3, 4 and 5 composite • Extensive deforestation. • Fig 6.31: Landsat TM band 4 image map • 13 individual TM scenes + mosaic

  31. 6.10 Landsat-6 planned mission • A failed mission • Enhanced Thematic Mapper (ETM) • TM+ panchromatic band (0.5~0.9 mm) with 15m resolution. • Set 9-bit A-to-D converter to a high or low gain 8-bit setting from the ground. • Low reflectance  water  high gain • Bright region  deserts  low gain

  32. 6.11 Landsat ETM image simulation • Fig 6.32: Landsat ETM images

  33. 6.12 Landsat-7 • Launch: 1999 • Web site: http://landsat.gsfc.nasa.gov • Landsat 7 handbook • Landsat 7 in orbit • Depiction of Landsat 7

  34. 6.12 Landsat-7 (cont.) • Landsat 7 Orbit • Orbital paths • Swath • Swath pattern • Landsat data • http://landsat.gsfc.nasa.gov/main/data.html

  35. 6.12 Landsat-7 (cont.) • Payload • Enhanced Thematic Mapper Plus (ETM+) • Dual mode solar calibrator • Data transmission • TDRSS or stored on board. • GPS  subsequent geometric processing of the data • High Resolution Multi-spectral Stereo Imager (HRMSI) • 5m panchromatic band • 10m ETM bands 1~4 • Pointable  revisit time (<3 days) Stereo imaging. • 00~380 cross-track and 00~300 along-track

  36. 6.12 Landsat-7 (cont.) • Application • Monitoring Temperate Forests • Mapping Volcanic Surface Deposits • Three Dimensional Land Surface Simulations

  37. 6.13 SPOT Satellite Program • Background • French+Sweden+Belgium • 1978 • Commercially oriented program • SPOT-1 • French Guiana, Ariane Rocket • 1986 • Linear array sensor+pushbroom scanning+pointable • Full-scene stereoscopic imaging

  38. 6.13 SPOT Satellite Program (cont.) • SPOT-2 • 1990 • SPOT-3 • 1993

  39. 6.14 Orbit characteristics of SPOT-1, -2 and -3 • Orbit • Circular, near-polar, sun-synchronous orbit • Altitude: 832km • Inclination: 98.70 • Descend across the equator at 10:30AM • Repeat: 26 days • Fig 6.33: SPOT revisit pattern at latitude 450 and 00 • At equator: 7 viewing opportunities exist • At 450: 11 viewing opportunities exist

  40. 6.15 Sensors onboard SPOT-1, -2 and -3 • Configuration (Fig 6.34) • 223.5m, 1750 kg, solar panel: 15.6m • Modular design • High Resolution Visible (HRV) imaging system • 2-mode • 10m-resolution panchromatic mode (0.51~0.73mm) • 20m-resolution color-infrared mode. (0.5~0.59mm, 0.61~0.68mm, 0.79~0.89mm)

  41. 6.15 Sensors onboard SPOT-1, -2 and –3 (cont.) • HRV (cont.) • Pushbroom scanning • No moving part (mirror)  lifespan • Dwell time  • Geometric error  • 4-CCD subarray • 6000-element subarray  panchromatic mode, 10m • Three 3000-element subarrays  multi-spectral mode, 20m • 8-bit, 25 Mbps • Twin-HRV instruments • IFOV (for each instrument)  4.130 • Swath: 60km  2 - 3km = 117km (Fig 3.36) • TFOV (for each instrument)  270=0.6045 (Fig 3.35)

  42. 6.15 Sensors onboard SPOT-1, -2 and –3 (cont.) • HRV (cont.) • Data streams • Although 2-mode can be operated simultaneously, only one mode data can be transmitted  limitation of data stream • Stereoscopic imaging • Off-nadir viewing capability (Fig 6.37) • Frequency  revisit schedule (Fig 6.33) • Base-height ratio  latitude • 0.75 at equator, 0.5 at 450 • Control • Ground control station  Toulouse, France  observation sequence • Receiving station  Tordouse or Kiruna, Sweden • Tape recorded onboard • Transmitted within 2600km-radius around the station

  43. 6.16 SPOT HRV image interpretation • Fig 6.38: SPOT-1 panchromatic image • 10m-resolution • Cf: Landsat MSS 80m • Cf: Landsat TM 30m (Fig 6.26) • Cf: Landsat ETM 15m (Fig 6.32) • Fig 6.39: SPOT-1 panchromatic image • Plate14: merge of multispectral & panchromatic data • Fig 6.40: SPOT-1 panchromatic image stereopair • Plate 15: Perspective view of Alps • SPOT stereopair + parallax calculation • Plate 23 • Fig 6.41: before and after the earthquake

  44. 6.17 SPOT –4 and –5 • SPOT –4 • Launched 1998 • Vegetation Monitoring Instrument (VMI) • Swath: 2000km daily global coverage • Resolution: 1km • Spectral band: b(0.43~0.47mm), g(0.5~0.59mm), r(0.61~0.68mm), N-IR(0.79~0.89mm), mid-IR(1.58~1.75mm)

  45. 6.17 SPOT –4 and –5 (cont.) • SPOT – 5 • Launched 2002 • Vegetation Monitoring Instrument (VMI) • Swath: 2000km daily global coverage • Resolution: 1km • Spectral band: b(0.43~0.47mm), g(0.5~0.59mm), r(0.61~0.68mm), N-IR(0.79~0.89mm), mid-IR(1.58~1.75mm)

  46. 6.18 Meteorological Satellite • Metsats • Coarse spatial resolution  land-oriented system • Very high temporal resolution of global coverage • NOAA satellites  sun-synchronous • GOES  geostationary  36,000km altitude • DMSP

  47. 6.18 Meteorological Satellite (cont.) • NOAA satellites • Advanced Very High Resolution Radiometer (AVHRR) • NOAA –6 ~ -12. (N-S) • Even: 7:30AM crossing time • Odd: 2:30 AM crossing time • Table 6.6: characteristics of NOAA-6 ~ -12 • Fig 6.42: Example coverage of the NOAA AVHRR • Ground resolution: 1.1km at nadir • AVHRR data • LAC • GAC • Fig 6.43: Comparison of Spectral sensitivity

  48. 6.18 Meteorological Satellite (cont.) • NOAA satellites (cont.) • Fig 6.44: AVHRR images • A: distortion  wide angle of view • B: geometric correction • Plate 16: NOAA AVHRR band 4 thermal image of the Great Lakes • Fig 6.45: AVHRR images of the Mississippi Delta • (a): present and past channels, future  Atchafalaya • (b): Channel–1 (red), silky material  visible • (c): Channel–2 (Near-IR), light tone  higher & drier • (d): Channel–4 (thermal –IR) light tone  cooler • Plumes of cooler river water

  49. 6.18 Meteorological Satellite (cont.) • NOAA satellites (cont.) • Plate 17: springtime NOAA-8 AVHRR color composite • Applications of AVHRR in monitoring vegetation • Use Ch-1 (0.58~0.68 mm) and Ch-2 (0.73~1.10 mm) • A simple vegetation index VI=Ch2-Ch1 • Normalized difference vegetation index NDVI = (Ch2-Ch1)/(Ch2+Ch1) • Vegetated areas  large VI Clouds, water, snow  negative VI Rock, Bare soil  VI  0 • For global vegetation  NDVI preferred  compensate the charging illumination conditions • Plate 18: color-coded NDVI • Select the highest NDVI during that period

  50. 6.18 Meteorological Satellite (cont.) • NOAA satellites (cont.) • Applications of AVHRR in monitoring vegetation (cont.) • Applications: vegetation seasonal dynamics at global and continental scale, tropical forest clearance, leaf area index measurement, biomass estimation, percentage ground cover determination, photosynthetically active radiation estimation • Other factors that might influence NDVI • Incident solar radiation • Radiometric response of the sensor • Atmospheric effect and viewing angle  need further research

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