More Remote Sensing

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					More Remote Sensing

         Today-

     - announcements
  -Review of few concepts
-Measurements from imagery
  -Satellites and Scanners
► http://ngs.woc.noaa.gov/katrina/
           Announcements
► Should  read chapter 6 for Thursday. Not on
  Syllabus!
► Bring rulers to class on Thursday… if you
  got one.
  Last lecture we talked about…
► Remote  sensing
► Map interpretation
► Geographical data acquisition, management,
  and analysis
► Introduction to Geographic Information
  Systems
► Map production
           Remote Sensing
► …isthe gathering of information by means
 of a sensor that is not in contact with the
 object being detected.
Nature of
EM
radiation
Atmospheric windows
              Remote Sensing
► Types   of sensors
   Active
   Passive
              Remote Sensing
► See   page 254 in Campbell
   Film
    ►Panchromatic
    ►Color
    ►False   Color IR
   Sensors
    ►Narrow-band
    ►Multispectral   devices
             Remote Sensing
► How   the image is taken..
   Vertical
   High-oblique (with horizon)
   Low-oblique (without horizon)
             Remote Sensing
► vertical
            Remote Sensing
► oblique
            Remote Sensing
► oblique
              Remote Sensing
► Why   use obliques??
              Remote Sensing
► Why   use obliques??
              Remote Sensing
► Summary     of a few things…
   Remote sensing instruments can be divided in
    many different ways…
    ►Active / passive
    ►Film / sensor
    ►Narrow band / multispectral
    ►Angle of photo / scan
              Remote Sensing
► Aerial   Photos…
   how they are made… p. 258
   Planimetric Shift… p. 260
     OK, so… some new stuff…
► Scale…..
   Large and small
                       Scale
► Large   scale is local

► Small   scale is global
                   Scale
► Word scales
► Representative fraction
► Graphic
                     Scale
► 1:24,000   topos

► Britsdo word scale..
1 inch represents one mile

A.K.A. 1 : 63,360
Graphic scale
     Finding scale on an image
► Find   something on photo with a known size

► Compareto a map or other photo with a
 known scale.
     Measuring stuff on an image
        - Photogrammetry -
► Linear
   Dimensional analysis
     Measuring stuff on an image
        - Photogrammetry -
► Linear
   Dimensional analysis


► Area
        Measuring stuff on an image
           - Photogrammetry -
► But   what if they are squiggly features???



► Linear
   Dimensional analysis


► Area
     Measuring stuff on an image
        - Photogrammetry -
► Linear
   Dimensional analysis


► Area


► Height
   Shadows
   Planimetric shift
 See photo in Remote Sensing book

► Video   projector
           Measuring stuff on an image
              - Photogrammetry –
►   What about the effects of mountains and terrain on
    measurements??


►   Linear
     Dimensional analysis

►   Area

►   Height
     Shadows
     Planimetric shift
  Scanners and satellite imagery
► How   scanners work…. As opposed to photos
► Pixels
► Often 256 values 0 – 255 levels of detection
► Multispectral
   Bands covered… 3 in visible, near IR and Far IR
   Also radar and microwave (active systems)
             Start here…..
     Scanners and satellite imagery
►A  brief history of satellites
► 1972 Landsat.
   1-4 no longer work, 6 bit it. 5 and 7 still
    working
   Cover same spot on earth about every 16 days
   “Whisk broom scanner”
   Multispectral scanner and thematic mapper
  Scanners and satellite imagery
► Multispectral   scanner
   79 by 79 resolution
   See page 272 (top) for bands covered
►   The MSS can simulate rather crude spectral signatures. Bands 4, 5, and 6 each have a
    bandwidth of 0.1 µm; and band 7's width is 0.3 µm. We represent band responses by bars
    in a histogram-like plot, in which the height of the bar signifies the relative reflectances
    averaged for all wavelengths within the bandwidth interval..

    From…http://rst.gsfc.nasa.gov/Intro/Part2_18.html
From
http://www.grid.unep.ch/proser
/remotesens/iraq.php. Landsat
image: MSS Bands 4, 2 and 1,
taken on 16 February 1973, 14
February 1975 and 27 May
1976.
  Scanners and satellite imagery
► Multispectral   scanner
   79 by 79 resolution
   See page 272 (top) for bands covered


► thematic   mapper
   30 x 30 resolution (thermal – 120 or 60)
   See page 273 for bands covered
  Scanners and satellite imagery
► Resolution
   Object needs to be 2x resolution to be seen
    (reliably)
From
http://www.grid.unep.
ch/proser/remotesens/
iraq.php. Landsat
image: ETM Bands 4, 3
and 2, taken on 26
March and 4 May
2000.
Atmospheric windows
► TM  image
► Bands 2, 3, 4
► Displayed
  blue, green,
  red
►   25-Meter MultispectraL,
    Landsat TM, Bands 7,4,3
    (RGB), Acquired
    February 13, 1989. In
    this image of Hong
    Kong, vegetation
    appears in green, bare
    soil is reddish purple,
    and urban features are
    purple and white. This
    particular band
    combination easily
    distinguishes water/land
    boundaries because
    water bodies (shown in
    black) contrast strongly
    with colorful land
    features.
►   From
    http://landsat.gsfc.nasa.
    gov/images/gallery.html
► http://www.siskiyous.edu/shasta/map/sat/
 Scanners and satellite imagery
► SPOT
     „push-broom‟ scanner
     3 visible and near IR
     20 meter multispect and 10 meter single
     Fly-over same spot each 20 days (apx)
     Can be pointed away from vertical. Uses?
       ►Stereopairs,   more frequent observations
  Scanners and satellite imagery
► IKONOS
   1 meter (page 274 in book)

► Active
   Radar and microwave



► Military
   ??????
  Scanners and satellite imagery
► Contrast   stretching and edge enhancement

(page. 276)
To Summarize……
              Remote Sensing
► Summary     of a few things…
   Remote sensing instruments can be divided in
    many different ways…
    ►Active / passive
    ►Film / sensor
    ►Narrow band / multispectral
    ►Angle of photo / scan
              Photogrammetry
► Summary
     Scale
     Measurements, linear, area, height
     Dimensional analysis
     Effects of topography
 Scanners and satellite imagery
► Summary
     Pixels and scanners
     MSS, TM, SPOT, etc
     Resolution
     Bands
     „false color‟
     Comparisons
     Image enhancement

				
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posted:10/28/2011
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