Fundamentals of remote sensing overview

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Fundamentals of remote sensing overview
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Energy exchange

• Passive sensing
• Solar radiation
• Emittance
• Atmospheric attenuation
• Surface interactions
• Reflectance
• Active sensing
• Emitted energy (frequency, polarisation)
• Atmospheric attenuation
• Reflectance / backscatter
• Signatures / polarimetry / interferometry

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Atmospheric processes

• Scattering
• Mie scattering
• Raleigh scattering
• Non-selective scattering
• Absorption
• Conduction
• Charge transfer
• Crystal field
• Vibrational

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Spectral processes

• Conduction bands
• Fe2,Fe3 embedded in crystal lattice and
  electrons shared rather than owned by one atom
• Charge transfer processes
• special case of semi-conductor behaviour where
  electrons transfer from one atom to another eg.
  Fe and O causing absorption in the UV region

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Spectral processes

• Crystal field or ligand field
• transition elements Fe, Cr, Ni, Ti, Co, Mn, Wo
  and Sc all have unfilled 3d shells that determine
  the energy levels but are under the influence of
  the crystal field in which they are embedded
• in certain crystal lattice structures a crystal
  field results from valence electron pairs being
  more closely associated with some ions rather
  than others. Eg. Al and O in corundrum or Cr and
  O in Ruby

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Spectral processes

• Vibrational processes
• small displacements of atoms within their bond
  structure
• Absorption features due to transitions from one
  energy state to another
• Fundamental frequencies ground state to vi1
• Overtone frequencies ground state to vi2 or
  more
• where i mode of vibration

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Spectral processes

• Vegetation
• Chlorophyll-a chlorophyll-b, carotine, xanophyll
• liquid water
• proteins, starch, lignin
• cellulose
• carbohydrates
• transmission through leaves and plant canopies
• arrangement of leaves in canopy
• refractive index of light through cell interface

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Spectral processes

• Field conditions
• Spectral mixing
• Effect of grain size
• View angle
• Moisture content
• Reference material

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The four image resolutions

• Spatial
• Spectral
• Radiometric
• Temporal

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Typical remote sensing devices

• Frame camera
• Panoramic camera
• Cross-track scanner
• Along-track scanner
• Side looking

• Metric air photography
• CORONA
• Landsat TM / ETM
• SPOT HRV
• RADAR