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Remote Sensing Data Acquisition

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Title: Remote Sensing Data Acquisition


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
(No Transcript)
6
  • http//nationalmap.gov/viewer.html
  • http//www.abc.net.au/news/events/japan-quake-2011
    /beforeafter.htm

7
Electro-Optical Remote Sensing
  • Detector
  • Process
  • Vehicle
  • Products Digital images

8
Buffalo, NY November 20, 2000
http//earthobservatory.nasa.gov/Newsroom/NewImage
s/images.php3?img_id4396
9
Biloxi CoastBefore Hurricane Katrina, April 12,
2005
Biloxi CoastAfter Hurricane Katrina, August 31,
2005.
http//www.esri.com/news/pressroom/hurricanemaps.h
tml
10
Microwave Remote Sensing
  • Uses antennas as detectors
  • Passive microwave systems
  • Active microwave systems, RADAR

11
http//rst.gsfc.nasa.gov/Sect8/Sect8_3.html
http//www.erh.noaa.gov/buf/
12
Close Range Remote Sensing

13
  • Visual interpretation vs. digital image
    processing

14
2. Resolutions
  • Spectral resolution
  • Radiometric resolution
  • Spatial resolution
  • Temporal resolution

15
Spectral Resolutions

16
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
17
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
18
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
19
Temporal Resolution
  • How often a given sensor obtains imagery of a
    particular area, e.g., 16 days, daily

20
Pixels and IFOV
  • Pixel - picture element
  • IFOV - Instantaneous Field of View the ground
    area viewed by the sensor at a given instant

21
3. Color Theory
  • Additive primaries
  • Subtractive primaries

22
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

23
Color Theory
  • Yellow, magenta, and cyan are complements of
    blue, green, and red, respectively
  •  Various combinations of the three primaries
    produce different colors

24
Subtractive Primaries
  • yellow, magenta, and cyan each absorbs its
    complementary color from white light          
    yellow  white - blue           magenta white
    - green           cyan  white - red

25
Subtractive Primaries
  • Superimposing yellow, magenta, and cyan dye
          yellow  magenta cyan black       
    yellow  magenta red        yellow  cyan 
    green        magenta cyan  blue

26
True and False Color Images
27
True and False Color Images
http//www.crisp.nus.edu.sg/research/tutorial/opt
_int.htm
28
  • Readings Chpt 2.7

29
4. Introduction of Satellite Systems
  •  Land observation satellite systems
  •         vehicles - spacecraft         devices
    - electro-optical sensors         images -
    digital images         target - earth resources

30
Satellite Systems
  •  Advantages vs. aerial photography
  • provide a synoptic view systematic,
    repetitive coverage multiple spectral
    information digital format for quantitative
    analysis less expensive

31
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

32
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

33
Satellite Orbits
  • Geosynchronous orbits
  • Sun-synchronous orbits
  • Inclination
  • Ascending and descending nodes   

34
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/spa
cebrn.htm
35
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/spa
cebrn.htm
http//www.youtube.com/watch?vLttI1IofXRI
36
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
37
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/f
undam/chapter2/chapter2_2_e.html
38
Satellite Orbits
  • Most satellites cross over the equator at about
    930am, an optimal time with respect to sun angle
    and cloud cover
  •  

39
Readings
  • Chapter 6
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