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CHAPTER 2

FUNDAMENTALS. CHAPTER 2. Basic Definitions And Laws Of Electromagnetic Radiation. A. Dermanis. Sensors collect electromagnetic energy Δ Q emitted from a surface area Δ Α (pixel), during a time interval Δ t , arriving at the sensor aperture with a solid angle ΔΩ. ΔΩ. P. Δ Α.

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CHAPTER 2

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  1. FUNDAMENTALS CHAPTER 2 Basic Definitions And Laws Of Electromagnetic Radiation A. Dermanis

  2. Sensors collect electromagnetic energyΔQ emitted froma surface areaΔΑ (pixel), during a time intervalΔt, arriving at the sensor aperture with a solid angleΔΩ ΔΩ P ΔΑ A. Dermanis

  3. Sensors collect electromagnetic energyΔQ emitted froma surface areaΔΑ (pixel), during a time intervalΔt, arriving at the sensor aperture with a solid angleΔΩ ΔΩ Το characterize the “intensity” of electromagnetic radiation we must get rid of ΔΑ, Δt andΔΩ ! P ΔΑ A. Dermanis

  4. Sensors collect electromagnetic energyΔQ emitted froma surface areaΔΑ (pixel), during a time intervalΔt, arriving at the sensor aperture with a solid angleΔΩ ΔΩ Το characterize the “intensity” of electromagnetic radiation we must get rid of ΔΑ, Δt andΔΩ ! P ΔΑ Basic definitions (Q = energy) A. Dermanis

  5. Sensors collect electromagnetic energyΔQ emitted froma surface areaΔΑ (pixel), during a time intervalΔt, arriving at the sensor aperture with a solid angleΔΩ ΔΩ Το characterize the “intensity” of electromagnetic radiation we must get rid of ΔΑ, Δt andΔΩ ! P ΔΑ Basic definitions (Q = energy) radiant flux Φ(t): (power !) A. Dermanis

  6. Sensors collect electromagnetic energyΔQ emitted froma surface areaΔΑ (pixel), during a time intervalΔt, arriving at the sensor aperture with a solid angleΔΩ ΔΩ Το characterize the “intensity” of electromagnetic radiation we must get rid of ΔΑ, Δt andΔΩ ! P ΔΑ Basic definitions (Q = energy) radiant flux Φ(t): (power !) radiant exitance M(t,P): (emitted) A. Dermanis

  7. Sensors collect electromagnetic energyΔQ emitted froma surface areaΔΑ (pixel), during a time intervalΔt, arriving at the sensor aperture with a solid angleΔΩ ΔΩ Το characterize the “intensity” of electromagnetic radiation we must get rid of ΔΑ, Δt andΔΩ ! P ΔΑ Basic definitions (Q = energy) radiant flux Φ(t): (power !) radiant exitance M(t,P): (emitted) irradiance E(t,P): (incident) A. Dermanis

  8. Sensors collect electromagnetic energyΔQ emitted froma surface areaΔΑ (pixel), during a time intervalΔt, arriving at the sensor aperture with a solid angleΔΩ ΔΩ Το characterize the “intensity” of electromagnetic radiation we must get rid of ΔΑ, Δt andΔΩ ! P ΔΑ Basic definitions (Q = energy) radiant flux Φ(t): (power !) radiant exitance M(t,P): (emitted) irradiance E(t,P): (incident) (π = half upper space) illuminance L: A. Dermanis

  9. Electromagnetic signals x(t) consist of sines and cosines with varying periods T, or angular frequencies ω=2π/Τ, or wavelengths λ=cT (c = light velocity) A. Dermanis

  10. Electromagnetic signals x(t) consist of sines and cosines with varying periods T, or angular frequencies ω=2π/Τ, or wavelengths λ=cT (c = light velocity) Fourier analysis: A. Dermanis

  11. signal power: S(ω) = power spectral density function A. Dermanis

  12. signal power: S(ω) = power spectral density function radiant flux (power): exitance (with ωλ=cT=2πc/ω): A. Dermanis

  13. signal power: S(ω) = power spectral density function radiant flux (power): exitance (with ωλ=cT=2πc/ω): = spectral exitance A. Dermanis

  14. Sensors respond to exitance only within a spectral band λ1  λλ2 : Ideal sensor: A. Dermanis

  15. Sensors respond to exitance only within a spectral band λ1  λλ2 : Ideal sensor: Actual sensor: w(λ) = sensor sensitivity response function A. Dermanis

  16. Sensors respond to exitance only within a spectral band λ1  λλ2 : Ideal sensor: Actual sensor: w(λ) = sensor sensitivity response function response functions for the 4 sensors of the Landsat satellite Multispectral Scanner A. Dermanis

  17. The Electromgnetic Spectrum λ cm A 102 102 0.1 1 10 103 104 105 106 0.1 1 10 103 104 105 106 107 μ A m km cm 0.3 0.2 3 30 300 0.3 3 30 300 0.3 3 30 3 30 300 3 30 300 RADAR γ RADIO AUDIO AC Χ MICROWAVES IR UV VISIBLE UV (Ultraviolet)  Violet Red  IR (Infrared) A. Dermanis

  18. Spectral Bands of Landsat Satellite - Thematic Mapper (T1, T2, T3, T4, T5) and SPOT4 Satellite – HRVIR (S1, S2, S3, S4) 1. water 2. vegetation 3. bare soil 4. snow A. Dermanis

  19. Laws of Electromgnetic Radiation black body : an idealized body absorbing all wavelengths of incident radiation or emitting radiation at all wavelengths Physical approximation = sun! T = temperature A. Dermanis

  20. Laws of Electromgnetic Radiation black body : an idealized body absorbing all wavelengths of incident radiation or emitting radiation at all wavelengths Physical approximation = sun! T = temperature Law of Plank: (spectral exitance of black body) A. Dermanis

  21. Laws of Electromgnetic Radiation black body : an idealized body absorbing all wavelengths of incident radiation or emitting radiation at all wavelengths Physical approximation = sun! T = temperature Law of Plank: (spectral exitance of black body) Law of Stefan-Bolzman: (total spectral exitance) A. Dermanis

  22. Laws of Electromgnetic Radiation black body : an idealized body absorbing all wavelengths of incident radiation or emitting radiation at all wavelengths Physical approximation = sun! T = temperature Law of Plank: (spectral exitance of black body) Law of Stefan-Bolzman: (total spectral exitance) Law of Wien: (λ of maximal spectral exitance) A. Dermanis

  23. The Solar Electromgnetic Radiation solar irradiance below atmosphere atmospheric absorption A. Dermanis

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