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Mirosława Szopa

Mirosława Szopa

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Military University of Technology Institute o f Optoelectronics. Correction of reflectance characteristics of chosen natural and anthropogenic materials for airborne laser scanning system. Mirosława Szopa. INCIDENT LIGHT. REFLECTION. EMISSION. ABSORPTION. TRANSMISSION. - PowerPoint PPT Presentation

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Page 1: Mirosława Szopa

Mirosława Szopa

Page 2: Mirosława Szopa

Electromagnetic radiation which interact with boundary of two media

characterized by different refractive index, undergo four various phenomena:

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INCIDENT LIGHT

EMISSION

TRANSMISSION

ABSORPTION

REFLECTION

Page 3: Mirosława Szopa

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SPECULAR BACKREFLECTION SPECULAR-DIFFUSE

DIFFUSE REAL

Characteristics of reflection are depended on physical properties of optic materials,

characteristics of boundary layer, and wavelength of incident radiation

Page 4: Mirosława Szopa

Reflectance is a proportion between power of reflected beam and incident beam of radiation and can be expressed

as a fraction (R1),

as a percent (R2),

or decibels (R3):

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INC

REF

P

PR 1

%1002

INC

REF

P

PR

INC

REF

P

PR 103 log10

Page 5: Mirosława Szopa

Effective Target Cross Section Effective Target Cross Section (ETCS) (ETCS)

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SOLID ANGLE

SOURCEOF LIGHT

PARAMETERS OF REFLECTING MATERIAL

AR

4

reflectancein decibels

target area

solid angle

Page 6: Mirosława Szopa

Values of reflectance Values of reflectance of chosen materialsof chosen materials

613

0,5 1,0 1,5 2,0 2,5 WAVELENGTH [um]

RE

FLE

CT

AN

CE

[

%]

0

2

0

40

60

8

0 ICE

GREEN PLANT

CONCRETE

Page 7: Mirosława Szopa

Reaching receivers signal, which carries information on analyzed material reflectance is subject to weakness on the path in atmosphere(extinction)caused by phenomena of light absorption and scattering,

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ReII 20

METEOROLOG

ICAL

VISIBILITY

EXTINCTION COEFFICIENT [km-1]

λ1 = 850 nm λ2 = 900 nm λ3 = 1500 nm

10 km 0.234 0.216 0.097

15 km 0.154 0.142 0.064

20 km 0.114 0.106 0.047

23 km 0.09860 0.091 0.041

Page 8: Mirosława Szopa

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Extinction of light for analyzed wavelengths :λ1 = 850 nm, λ2 = 900 nm, λ3 = 1500 nm

with chosen atmospheric conditions (described by meteorological visibility)

Page 9: Mirosława Szopa

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Extinction of radiation on the path in atmosphere causes disorders of signal proportions for chosen wavelengths.

Meteorological visibility = 10 km

SIGNAL PROPORTIONS 850/1500 nm

without extinctionwith extinction

SIGNAL PROPORTIONS 900/1500 nm

without extinctionwith extinction

SIGNAL PROPORTIONS 850/900 nm

without extinctionwith extinction

Page 10: Mirosława Szopa

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Correction was carried out with allowance of character of reflection obtained from materials, various atmospheric

conditions stated by meteorological visibility, and spectral characteristics of atmospheric extinction.

SIGNAL PROPORTIONS 850/1500 nm

without extinctionwith correction

SIGNAL PROPORTIONS 900/1500 nm

without extinctionwith correction

SIGNAL PROPORTIONS 850/900 nm

without extinctionwith correction

Page 11: Mirosława Szopa

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The proposed method of correction provides minimization

of real values falsification and decrease in obtained measurement

errors, which do not exceed the value of 5%

for the analyses from a distance of 0.5 km with atmospheric visibility of 10 km,

and for the analyses from a distance of 1 km with atmospheric visibility of 20 km.

Page 12: Mirosława Szopa

CONCLUSIONCONCLUSIONBasing on the fundamental assumption

of the remote sensing technique, which says that every material has its own

specific spectral characteristics, and after precise analysis of reflectance

of chosen materials, it is possible to elaborate the airborne laser scanner.

The aim of this scanner would be detection and localization of materials and objects

in analyzed area of space on the basis of reflection signal analysis

using proposed method of signal correction .

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Page 13: Mirosława Szopa

Tytuł 13/13