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Mirosława Szopa. Electromagnetic radiation which interact with boundary of two media characterized by different refractive index, undergo four various.

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Presentation on theme: "Mirosława Szopa. Electromagnetic radiation which interact with boundary of two media characterized by different refractive index, undergo four various."— Presentation transcript:

1 Mirosława Szopa

2 Electromagnetic radiation which interact with boundary of two media characterized by different refractive index, undergo four various phenomena: 2/13 INCIDENT LIGHT EMISSION TRANSMISSION ABSORPTION REFLECTION

3 3/13 SPECULARBACKREFLECTION SPECULAR-DIFFUSE DIFFUSEREAL Characteristics of reflection are depended on physical properties of optic materials, characteristics of boundary layer, and wavelength of incident radiation

4 Reflectance is a proportion between power of reflected beam and incident beam of radiation and can be expressed as a fraction (R 1 ), as a percent (R 2 ), or decibels (R 3 ): 4/13

5 Effective Target Cross Section (ETCS) 5/13 SOLID ANGLE SOURCE OF LIGHT PARAMETERS OF REFLECTING MATERIAL reflectance in decibels target area solid angle

6 Values of reflectance of chosen materials 613 0,5 1,0 1,5 2,0 2,5 WAVELENGTH [um] REFLECTANCE [%] ICE GREEN PLANT CONCRETE

7 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, 7/13 METEOROLOG ICAL VISIBILITY EXTINCTION COEFFICIENT [km -1 ] λ 1 = 850 nmλ 2 = 900 nmλ 3 = 1500 nm 10 km km km km

8 8/13 Extinction of light for analyzed wavelengths : λ 1 = 850 nm, λ 2 = 900 nm, λ 3 = 1500 nm with chosen atmospheric conditions (described by meteorological visibility)

9 9/13 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 extinction with extinction SIGNAL PROPORTIONS 900/1500 nm without extinction with extinction SIGNAL PROPORTIONS 850/900 nm without extinction with extinction

10 10/13 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 extinction with correction SIGNAL PROPORTIONS 900/1500 nm without extinction with correction SIGNAL PROPORTIONS 850/900 nm without extinction with correction

11 11/13 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.

12 CONCLUSION Basing 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. 12/13

13 Tytuł13/13


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