chapter 5 atmospheric influence and radiometric correction pre-processing a. dermanis
TRANSCRIPT
CHAPTER 5CHAPTER 5
Atmospheric InfluenceAtmospheric Influenceand Radiometric Correctionand Radiometric Correction
PRE-PROCESSINGPRE-PROCESSING
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Ideal situation:
- sun and sensorabove observed pixel,
- flat terrain,- no atmosphere.
Ideal situation:
- sun and sensorabove observed pixel,
- flat terrain,- no atmosphere.
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Ideal situation:
- sun and sensorabove observed pixel,
- flat terrain,- no atmosphere.
Ideal situation:
- sun and sensorabove observed pixel,
- flat terrain,- no atmosphere.
E0 = incident irradiance
Er = reflected irradiance
ρ = reflectivity (caracterizes pixel class)
L0 = illuminance
(recorded at sensor)
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Ideal situation:
- sun and sensorabove observed pixel,
- flat terrain,- no atmosphere.
Ideal situation:
- sun and sensorabove 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 spacewhere Er is diffused
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Influence of atmosphere:
- Incident irradiance E0 reduced
by a factor T0,
- reflected illuminance L0 reduced
by a factor T0.
Influence of atmosphere:
- Incident irradiance E0 reduced
by a factor T0,
- reflected illuminance L0 reduced
by a factor T0.
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Influence of atmosphere:
- Incident irradiance E0 reduced
by a factor T0,
- reflected illuminance L0 reduced
by a factor T0.
Influence of atmosphere:
- Incident irradiance E0 reduced
by a factor T0,
- reflected illuminance L0 reduced
by a factor T0.
0 0
0 00 0
,
S
E ρT E
ρT EEL T T
π π
=
= =
LS = illuminance
(recorded at sensor)
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
E = incident irradiance reducedby 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
Atmospheric InfluenceAtmospheric Influence
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
E = incident irradiance reducedby 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
Atmospheric InfluenceAtmospheric Influence
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
- sun at zenith angle θover observed pixel,
- sensor at zenith angle over observed pixel.
E = incident irradiance reducedby 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
0( )cosθE T E θ=0( )cosθ
T φ φ
ρ T E θρEL T T
π π= =
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Atmospheric InfluenceAtmospheric Influence
Additional incident irradiance EDdiffused from atmosphere(origin: sun and other earth pixels)
Additional incident irradiance EDdiffused from atmosphere(origin: sun and other earth pixels)
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Additional incident irradiance EDdiffused from atmosphere(origin: sun and other earth pixels)
Additional incident irradiance EDdiffused from atmosphere(origin: sun and other earth pixels)
EG = incident irradiance
LT = illuminance
(recorded at sensor)
0cosG θ DE θT E E= +
(cos )
GT φ
θ G Dφ
ρEL T
π
ρ θT E ET
π
= =
+=
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Additional illuminance LPdiffused from atmosphere(origin:
sun and other earth pixels)
Additional illuminance LPdiffused from atmosphere(origin:
sun and other earth pixels)
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Additional illuminance LPdiffused from atmosphere(origin:
sun and other earth pixels)
Additional illuminance LPdiffused from atmosphere(origin:
sun and other earth pixels)
LS = illuminance
(recorded at sensor)
S φ T PL T L L= +
A. Dermanis
Atmospheric InfluenceAtmospheric Influence
Final situation:
E0 = incident irradiance from sun
Tθ = atmospheric absorbance on
incident irradiancecosθ = reduction factor for pixel
inclined to incident radiation ED = irradiance diffused from
atmosphereρ = pixel reflectanceπ = solid angle of
upper half spaceTφ = atmospheric absorbance on
reflected illuminanceLP = illuminance diffused from
atmosphere
Final situation:
E0 = incident irradiance from sun
Tθ = atmospheric absorbance on
incident irradiancecosθ = reduction factor for pixel
inclined to incident radiation ED = irradiance diffused from
atmosphereρ = pixel reflectanceπ = solid angle of
upper half spaceTφ = atmospheric absorbance on
reflected illuminanceLP = illuminance diffused from
atmosphere
A. Dermanis
00(cos ) cosS φ θ D P φ θ φ D P
Eρ ρL T θT E E L T θT ρ T E L
π π πé ùé ù= + + = + +ë û ê úë û
Radiometric CorectionRadiometric Corection
illuminance arriving at sensor:
A. Dermanis
00(cos ) cosS φ θ D P φ θ φ D P
Eρ ρL T θT E E L T θT ρ T E L
π π πé ùé ù= + + = + +ë û ê úë û
Radiometric CorectionRadiometric Corection
instead of ideal: 00
EL ρ
π=
illuminance arriving at sensor:
0SL A L B= +
( , , ) cosφ θA A θφ T θT= =a
( , , ) φ D Pρ
B B φ ρ T E Lπ
= = +aa = atmospheric condition parameters
A. Dermanis
00(cos ) cosS φ θ D P φ θ φ D P
Eρ ρL T θT E E L T θT ρ T E L
π π πé ùé ù= + + = + +ë û ê úë û
Radiometric CorectionRadiometric Corection
instead of ideal: 00
EL ρ
π=
illuminance arriving at sensor:
0SL A L B= +
( , , ) cosφ θA A θφ T θT= =a
( , , ) φ D Pρ
B B φ ρ T E Lπ
= = +a
recorded at sensor: Sx kL C= +
k0, C0 = nominal sensor parametersinstead of ideal: 0 0 0 0x k L C= +
a = atmospheric condition parameters
A. Dermanis
00(cos ) cosS φ θ D P φ θ φ D P
Eρ ρL T θT E E L T θT ρ T E L
π π πé ùé ù= + + = + +ë û ê úë û
Radiometric CorectionRadiometric Corection
instead of ideal: 00
EL ρ
π=
illuminance arriving at sensor:
0SL A L B= +
( , , ) cosφ θA A θφ T θT= =a
( , , ) φ D Pρ
B B φ ρ T E Lπ
= = +a
recorded at sensor: Sx kL C= +
k0, C0 = nominal sensor parametersinstead of ideal: 0 0 0 0x k L C= +
Radiometric correction: Recovery of x0 from x
a = atmospheric condition parameters
A. Dermanis
Radiometric CorrectionRadiometric 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
0SL B
LA-
= 0 0 0 0x k L C= +
Sx k
LC-
=
A. Dermanis
(a) Sensor Calibration: Computation of k and C
(b) Radiometric correction for sensor instability
(c) Determination of atmospheric influence parameters
Sx k
LC-
=
θ (flat terrain) = from astronomic ephemeris(replaced by ω for inclined terrain)
Radiometric CorrectionRadiometric Correction
A. Dermanis
(a) Sensor Calibration: Computation of k and C
(b) Radiometric correction for sensor instability
(c) Determination of atmospheric influence parameters
Sx k
LC-
=
θ (flat terrain) = from astronomic ephemeris(replaced by ω for inclined terrain)
φ = from satellite orbit
Radiometric CorrectionRadiometric Correction
A. Dermanis
(a) Sensor Calibration: Computation of k and C
(b) Radiometric correction for sensor instability
(c) Determination of atmospheric influence parameters
Sx k
LC-
=
θ (flat terrain) = from astronomic ephemeris(replaced by ω for inclined terrain)
φ = from satellite orbit
Tθ, Τφ = from atmospheric pressure, temperature, humidity
Radiometric CorrectionRadiometric Correction
A. Dermanis
(a) Sensor Calibration: Computation of k and C
(b) Radiometric correction for sensor instability
(c) Determination of atmospheric influence parameters
Sx k
LC-
=
θ (flat terrain) = from astronomic ephemeris(replaced by ω for 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!)
Radiometric CorrectionRadiometric Correction
A. Dermanis
(a) Sensor Calibration: Computation of k and C
(b) Radiometric correction for sensor instability
(c) Determination of atmospheric influence parameters
Sx k
LC-
=
( , , ) cosφ θA A θφ T θT= =a ( , , ) φ D Pρ
B B φ ρ T E Lπ
= = +a
θ (flat terrain) = from astronomic ephemeris(replaced by ω for 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:
Radiometric CorrectionRadiometric Correction
A. Dermanis
unknown !
(a) Sensor Calibration: Computation of k and C
(b) Radiometric correction for sensor instability
(c) Determination of atmospheric influence parameters
Sx k
LC-
=
( , , ) cosφ θA A θφ T θT= =a ( , , ) φ D Pρ
B B φ ρ T E Lπ
= = +a
θ (flat terrain) = from astronomic ephemeris(replaced by ω for 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:
Radiometric CorrectionRadiometric Correction
A. Dermanis
unknown !
(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
0SL B
LA-
= 0 0 0 0x k L C= +
Sx k
LC-
=
( , , ) cosφ θA A θφ T θT= =a ( , , ) φ D Pρ
B B φ ρ T E Lπ
= = +a
θ (flat terrain) = from astronomic ephemeris(replaced by ω for 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:
Radiometric CorrectionRadiometric Correction
A. Dermanis