Geomatics in the Classroom!

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Welcome Geomatics in the Classroom!
Power Point Presentation adapted by Claude Brun
del Re
Canadian Space Agency
Agence spatiale canadienne
Natural Resources Canada
Ressources naturelles Canada
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What is Geomatics ?

• Geomatics for Educators

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Geomatics

• Term originally created in Canada
• Geomatics is the science and technology of
  gathering, analyzing, interpreting, distributing
  and using geographic information. Geomatics
  encompasses a broad range of disciplines that can
  be brought together to create a detailed but
  understandable picture of the physical world and
  our place in it. These disciplines include
• Mapping and Surveying
• Geographic Information Systems (GIS)
• Global Positioning System (GPS)
• Remote Sensing

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Canadas Role in Geomatics

• Canada exports 300 million worth of geomatics
  products and services.
• Growth rate of 15 to 20 per cent per year.
• Demand for GIS products and services is expected
  to exceed 10 billion per year.
• Geomatics is one of the fastest-growing
  technology sectors and Canada is a recognized
  leader, both in its development and in the
  provision of Geomatics software, hardware and
  value-added services.
• Natural Resources Canada-
• Geomatics Canada
• Canada Centre for Remote Sensing
• Centre for Topographic Information
• Aeronautical Charts Technical Services
• Legal Surveys International Boundary Commission
• Geodetic Survey

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Remote Sensing
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List examples of remote sensing technology in
your every day life

• Satellite weather maps
• Ultrasounds
• Speed radar
• Sonar (for ships, bats or dolphin)

• Photos
• CAT scans
• x-rays

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REMOTE SENSING

• Definition and Process
• Target
• Sensor
• Platforms
• Electromagnetic Energy
• Interpretation
• RADARSAT

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Remote Sensing - A Definition

• Indirect (remote) observations (sensing)
• Remote sensing is the science (and to some
  extent, art) of acquiring image data and deriving
  information about the Earths surface without
  actually being in contact with it.
• Remote sensing will give information about an
  object called
• a target

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Who could give me two common sensors?

• Our eyes A camera

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How does remote sensing work?Far away from the
target, on what we call a platform.Here are some
types of platform

• Satellite
• Space shuttle
• Aircraft

• Balloon
• Ground base tower

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Remote Sensing Process

• Energy Source or Illumination (A)
• Radiation and the Atmosphere (B)
• Interaction with the Target or Surface (C)
• Recording of Energy by the Sensor (D)
• Transmission, Reception, and Processing (E)
• Interpretation and Analysis (F)
• Application (G)

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Passive Sensor

• Passive sensors detect or sense reflected solar
  radiation
• What does a passive sensor need
• to sense the earth?

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Active Sensors

• Active sensors produce and receive their own
  electromagnetic energy
• They produce their own illumination and they
• operate in the microwave region

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Some Atmospheric Interactions

• Energy will interact with the atmosphere on its
  way in and out
• Ozone, nitrogen, CO2 and water vapour affect
  incoming energy
• Energy affected if wavelength is lt or the
  particle size
• Atmospheric windows are
• wavelengths not affected by
• the atmosphere

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Absorption

• Some substances absorb certain wavelengths of
  energy
• UV rays absorbed by ozone
• LW IR and SW microwaves absorbed by water vapour
• These wavelengths are not suitable for remote
  sensing

Scattering

• Occurs when molecules are larger or equal to
  wavelength
• Rayleigh scattering - selective scattering (UV,
  Blue sky)
• Non-selective - scatters all visible wavelengths
  (clouds)

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Atmospheric Windows
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Terrain Interactions

• Radiation that reaches the Earths surface can
  be Absorbed (A) Transmitted (T) and Reflected
  (R).
• This will vary with the type of object. The type
  of interaction will depend on the wavelength of
  the energy and the material and condition of the
  feature.
• Look at different objects, for example an egg, a
  green apple and a tomato.

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Diffuse and Specular Reflectors
Diffuse Specular rough
surface smooth surface
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Electromagnetic Energy
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Electromagnetic Energy

• Electromagnetic energy is used to illuminate the
  target in remote sensing
• Electromagnetic spectrum
• Shorter wavelength Longer wavelength

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Visible Spectrum

• Visible Wavelegths
• Violet 0.4 - 0.446 mm
• Blue 0.446 - 0.500 mm
• Green 0.500 - 0.578 mm
• Yellow 0.578 - 0.592 mm
• Orange 0.592 - 0.620 mm
• Red 0.620 - 0.7 mm

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The basic colours of light
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IR and Microwaves

• Reflected IR 0.72 mm to 3.0 mm
• Thermal IR3.0 mm to 15 mm
• Microwaves1 mm to 1 m

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VIR or Optical Remote Sensing
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Visible / Infrared (VIR)

• Colours we perceive are combinations of
  electromagnetic energy
• VIR (visible infrared) or optical sensors capture
  energy reflected by targets in the optical and IR
  wavelengths
• Each target reflects or emits these types of
  energy in different amounts

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Spectral Response

• Different objects reflect, absorb and transmit
  energy in differing amounts
• An object also transmits, reflects, and absorbs
  each wavelength differently
• Spectral responses enable us to identify
  different objects on images
• An objects spectral response may change over time

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Spectral Response - Leaves

• Chlorophyll absorbs red and blue
• Reflects green
• Greenest in summer
• Internal leaf structure reflects near IR

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Bands or Channels

• Each sensor has a purpose (vegetation, ocean,
  ice, weather)
• Certain wavelengths provide more information
  about certain targets
• To perform their tasks, sensors on satellites
  detect energy in very specific, narrow bands or
  channels of electromagnetic energy

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VIR/Optical Sensors
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Spatial Resolution
Fine Resolution Coarse Resolution
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Swath

• Total field of view
• Width of the image in ground distance
• For satellites, variesbetween 10s to 100sof
  kilometres

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Orbits

• Geostationary Near-polar
  sun-synchronous

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GOES

• Geostationary Operational Environmental Satellite
• Operated by NOAA to for weather forecasting and
  monitoring
• 5 spectral bands (green-red to infrared)
• Geostationary above the equator at 75 degs E and
  W
• Resolution 1 to 4 kilometres

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NOAA-AVHRR

• Advanced Very High Resolution Radiometer
• Used for meteorology and other applications
  (vegetation)
• Sun-synchronous, near-polar orbits (830-870 km
  above the Earth)
• Ensure that data for any region of the Earth is
  no more than six hours old
• visible, near, mid infrared, thermal IR
• 3000 km swath, 1 to 4 km resoloution

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Landsat

• Landsat-1 was launched by NASA in 1972
• Landsat 7 was launched in 1999
• ETM (Enhanced Thematic Mapper) 8 bands VIR and
  Thermal IR
• 30 metre resolution
• 185 kilometre swath width
• Lots of archived data
• Near-polar, sun-synchronous orbits - 705 km

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SPOT

• Système Pour lObservation de la Terre
• French commercial satellites
• SPOT 1 -1986
• SPOT -2 operational, SPOT-4 just launched
• Sun-synchronous, near-polar orbits at altitudes
  around 830 km
• 2 Sensors MLA and PLA
• PLA - black and white
• MLA - 3 visible bands (blue-green-red)
• 60 to 80 km swath
• 10 to 20 m resolution

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RADARSAT-1

• Canadas first earth observation satellite
• Launched November 4, 1995
• Monitoring the Arctic (ice) is its main role
• Unique, flexible, steerable sensor
• Many swath width choices
• Many incidence angles available

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RADARSAT-1

• Repeat Cycle
• - 24 days
• - 14 orbits per day
• Coverage
• - Global 4,5 days
• - North America 3 days
• - Arctic daily
• Altitude
• - 798 km

• Orbit Geometry
• - Circular, Near polar
• - Sun-synchronous
• Inclination
• - 98.6 (from the equator)
• -Passes to the right of the
  North Pole
• Period
• - 100.7 Minutes

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New Small Sats

• 1 to 5 metre resolution
• All commercially built
• IKONOS
• Earlybird
• QuickBird

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RADAR
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RADAR

• RADAR is an acronym for RAdio Detection And
  Ranging
• A microwave (radio) signal is transmitted
  towards the target
• The sensor detects the reflected (or
  backscattered) portion of the signal

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RADAR Images

• Radar images look like black and white
  photographs
• Tones of gray correspond to the amount of radar
  energythat is returned to the sensor
• The stronger the backscatter or the more energy
  that is returned to the sensor, thelighter that
  area or object will appear on the final image

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RADAR Reflection

• There are three general types of
  reflectionspeculardiffuse corner

calm
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Advantages

• Own energy source (images anytime of day)
• Sees through clouds (images anywhere)
• Provides good view of topography
• Sensitive to surface roughness
• Provides information on moisture content

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Disadvantages

• Side-looking geometry creates distortions
• Radar speckle
• Excessive loss of data in mountainous areas due
  to shadows

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Radar Sensors

• SEASAT - NASA 1978
• lasted only a few months
• ERS-1 - ESA 1991-95
• 30 metre resolution
• ERS-2 - ESA 1994
• 30 metre resolution
• JERS-1 - Japan 1992
• 18 metre resolution

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Satellite Imagery
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What is an Image?

• Image is a visual view of the energy reflected by
  the target
• Satellite images are digital they are made up of
  numbers usually from 0 to 255 where 0 is black
  and 255 is white
• The numbers (radiance value) are arranged in rows
  and columns
• Each square is called a PIXEL
• A number or a value of reflected energy is stored
  for each pixel

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Raster Data

• Images are stored as raster data - grid of cells
  or pixels
• Each pixel represents a certain amount of ground
  like 10 m x 10 m
• Each pixel is representative of the amount of
  energy backscattered by the target

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Pixels and Lines

• Upper left corner is the origin
• X values are pixels or columns
• y values are lines or rows

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Pixels and Lines

• Pixels Lines
• X Pixel 2 and Line 2 ( 2, 2)

X
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Bits and Bytes

• Bits are binary digits (0 or 1)
• Images are collected as 8, 16, 32 bit data
• Bit refers to the number of exponential levels a
  binary digit is taken to
• single bit 21
• 8 bit 28 or 256 levels of grey
• 16 bit 216 or 65536 levels of grey

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Image File Formats

• .pix PCI or Eoscape
• .img ERDAS Imagine
• .lan ERDAS
• GeoTIFF .tiff contains georeferencing info
• TIF requires header file for georeferencing
• .bil, ,bsq, raw flat raster, common format,
  needs header file
• jpeg common image format for the WWW, no
  georeferencing information
• GRID ESRI raster format

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VIR Images

• Usually 3 bands loaded
• One band loaded aloneappears as a greyscale
• Each assigned a colourgun (Blue, green, red)
• Together, 3 bands formcolour image