CHAPTER 5

1. PRE-PROCESSING CHAPTER 5 Atmospheric Influence and Radiometric Correction A. Dermanis

2. Atmospheric Influence Ideal situation: - sun and sensor above observed pixel, - flat terrain, - no atmosphere. A. Dermanis

3. Atmospheric Influence Ideal situation: - sun and sensor above observed pixel, - flat terrain, - no atmosphere. E0= incident irradiance Er= reflected irradiance ρ= reflectivity (caracterizes pixel class) L0= illuminance (recorded at sensor) A. Dermanis

4. Atmospheric Influence Ideal situation: - sun and sensor above observed pixel, - flat terrain, - no atmosphere. E0= incident irradiance Er= reflected irradiance ρ= reflectivity (caracterizes pixel class) L0= illuminance (recorded at sensor) π = solid angle of upper half space where Er is diffused A. Dermanis

5. Atmospheric Influence Influence of atmosphere: - Incident irradiance E0 reduced by a factor T0, - reflected illuminance L0 reduced by a factor T0. A. Dermanis

6. Atmospheric Influence Influence of atmosphere: - Incident irradiance E0 reduced by a factor T0, - reflected illuminance L0 reduced by a factor T0. LS= illuminance (recorded at sensor) A. Dermanis

7. Atmospheric Influence - sun at zenith angle θ over observed pixel, - sensor at zenith angle  over observed pixel. A. Dermanis

8. Atmospheric Influence - sun at zenith angle θ over observed pixel, - sensor at zenith angle  over observed pixel. E= incident irradiance reduced by a factor Tθ > Τ0 (passing thicker layer) and by a factor cosθ (spread over larger area) LT= illuminance (recorded at sensor) reduced by a factor T > T0 A. Dermanis

9. Atmospheric Influence - sun at zenith angle θ over observed pixel, - sensor at zenith angle  over observed pixel. E= incident irradiance reduced by a factor Tθ > Τ0 (passing thicker layer) and by a factor cosθ (spread over larger area) LT= illuminance (recorded at sensor) reduced by a factor T > T0 A. Dermanis

10. Atmospheric Influence - sun at zenith angle θ over observed pixel, - sensor at zenith angle  over observed pixel. E= incident irradiance reduced by a factor Tθ > Τ0 (passing thicker layer) and by a factor cosθ (spread over larger area) LT= illuminance (recorded at sensor) reduced by a factor T > T0 A. Dermanis

11. Atmospheric Influence Additional incident irradiance ED diffused from atmosphere (origin: sun and other earth pixels) A. Dermanis

12. Atmospheric Influence Additional incident irradiance ED diffused from atmosphere (origin: sun and other earth pixels) EG= incident irradiance LT= illuminance (recorded at sensor) A. Dermanis

13. Atmospheric Influence Additional illuminance LP diffused from atmosphere (origin: sun and other earth pixels) A. Dermanis

14. Atmospheric Influence Additional illuminance LP diffused from atmosphere (origin: sun and other earth pixels) LS= illuminance (recorded at sensor) A. Dermanis

15. Atmospheric Influence Final situation: E0 = incident irradiance from sun Tθ = atmospheric absorbance on incident irradiance cosθ =reduction factor for pixel inclined to incident radiation ED = irradiance diffused from atmosphere ρ = pixel reflectance π = solid angle of upper half space Tφ =atmospheric absorbance on reflected illuminance LP = illuminance diffused from atmosphere A. Dermanis

16. Radiometric Corection illuminance arriving at sensor: A. Dermanis

17. Radiometric Corection illuminance arriving at sensor: instead of ideal: a = atmospheric condition parameters A. Dermanis

18. Radiometric Corection illuminance arriving at sensor: instead of ideal: a = atmospheric condition parameters recorded at sensor: k0, C0 = nominal sensor parameters instead of ideal: A. Dermanis

19. Radiometric Corection illuminance arriving at sensor: instead of ideal: a = atmospheric condition parameters recorded at sensor: k0, C0 = nominal sensor parameters instead of ideal: Radiometric correction: Recovery of x0 from x A. Dermanis

20. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters (d) Radiometric correction for atmospheric influence A. Dermanis

21. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters θ (flat terrain) = from astronomic ephemeris (replaced by ωfor inclined terrain) A. Dermanis

22. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters θ (flat terrain) = from astronomic ephemeris (replaced by ωfor inclined terrain) φ = from satellite orbit A. Dermanis

23. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters θ (flat terrain) = from astronomic ephemeris (replaced by ωfor inclined terrain) φ = from satellite orbit Tθ, Τφ= from atmospheric pressure, temperature, humidity A. Dermanis

24. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters θ (flat terrain) = from astronomic ephemeris (replaced by ωfor inclined terrain) φ = from satellite orbit Tθ, Τφ= from atmospheric pressure, temperature, humidity ED, LP =from atmospheric conditions related to scattering processes (extremely difficult to access!) A. Dermanis

25. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters θ (flat terrain) = from astronomic ephemeris (replaced by ωfor inclined terrain) φ = from satellite orbit Tθ, Τφ= from atmospheric pressure, temperature, humidity ED, LP =from atmospheric conditions related to scattering processes (extremely difficult to access!) computation of: A. Dermanis

26. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters θ (flat terrain) = from astronomic ephemeris (replaced by ωfor inclined terrain) φ = from satellite orbit Tθ, Τφ= from atmospheric pressure, temperature, humidity ED, LP =from atmospheric conditions related to scattering processes (extremely difficult to access!) unknown ! computation of: A. Dermanis

27. Radiometric Correction (a) Sensor Calibration: Computation of k and C (b) Radiometric correction for sensor instability (c) Determination of atmospheric influence parameters θ (flat terrain) = from astronomic ephemeris (replaced by ωfor inclined terrain) φ = from satellite orbit Tθ, Τφ= from atmospheric pressure, temperature, humidity ED, LP =from atmospheric conditions related to scattering processes (extremely difficult to access!) unknown ! computation of: (d) Radiometric correction for atmospheric influence A. Dermanis