Spectral Unmixing Applied to Desert Soils for the - Naval ...
Spectral Unmixing Applied to Desert Soils for the - Naval ... Spectral Unmixing Applied to Desert Soils for the - Naval ...
the Mazourka Canyon OHV park between Owens Valley and Death Valley at the base of the Inyo Mountains, the approximate coordinates for this site are 36 0 49’ 18”N, 118 0 05’ 17”W. A collection of spectra were also taken from the Santa Cruz mountains at approximately 37 0 07' 26.55"N, 122 0 00' 42.22"W for analysis of how soil reflectance changes with the same material under different disturbance conditions. B. METHODS 1. Atmospheric Correction Atmospheric correction must be performed on the AVIRIS data to remove the effects of atmospheric absorption and scattering in order to obtain the surface reflectance of a material for comparison to library spectra (Figure 16). Atmospheric corrections are applied on a pixel by pixel basis in order to analyze reflectance for materials in specific regions of the imagery. AVIRIS data were atmospherically corrected using the Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) method. Figure 16. In this figure from Birvio et al. (2001) the solar radiation interactions are illustrated. E0 is solar irradiance at the top of the atmosphere, Ed is diffuse solar irradiance. Ls represents radiance emitted from the target, Ld is the atmospheric path radiance and L0 is radiance measured by the sensor. θz and θv are downward and upward transmittance from the atmosphere, respectively, and θz and θv represent the solar zenith and sensor viewing zenith angles, respectively. 34
FLAASH, which supports hyperspectral sensors such as Hyperspectral Mapper (HyMAP), AVIRIS, Hyperspectral digital Imagery Collection experiment (HYDICE), and a few others as well as multispectral sensors like Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), is an automated atmospheric correction method developed by Spectral Sciences Inc. under sponsorship from the U.S. Air Force (Bernstein et al., 2012). FLAASH performs atmospheric correction on wavelengths in the visible through shortwave infrared regions (up to 3000 nm) incorporating Moderate Resolution Atmospheric Radiance and Transmission Model 4 (MODTRAN4) radiative transfer code into the processing. Options include standard MODTRAN atmosphere and aerosol types, but FLAASH also allows for correction for the adjacency affect, where pixel mixing occurs as a result of surface-reflected radiance scattering. An average aerosol/haze amount can also be calculated for the scene, and cirrus and opaque clouds can be masked (Kruse et al., 2004). FLAASH begins with the radiance equation at the sensor in the standard form of where: is pixel surface reflectance is the average surface reflectance for the pixel and the surrounding region is the atmosphere’s spherical albedo La is atmospherically back-scattered radiance are coefficients dependent on atmospheric and geometric conditions The values for A, B, S, and are determined using MODTRAN4 calculations that utilize viewing and solar angles and the mean surface elevation of the measurement. A model atmosphere, aerosol type, and visible range can be selected. The values for A, B, S, and are heavily dependent on the amount of water vapor present. To account for this, MODTRAN4 calculations are looped over a column amount series with selected 35 (3)
- Page 3 and 4: REPORT DOCUMENTATION PAGE Form Appr
- Page 5 and 6: Approved for public release; distri
- Page 7 and 8: ABSTRACT Desert areas cover approxi
- Page 9 and 10: TABLE OF CONTENTS I. INTRODUCTION..
- Page 11 and 12: LIST OF FIGURES Figure 1. The above
- Page 13 and 14: spectrum by atmospheric effects. Re
- Page 15 and 16: emoved function showing an absorpti
- Page 17 and 18: LIST OF TABLES Table 1. This table
- Page 19 and 20: LIST OF ACRONYMS AND ABBREVIATIONS
- Page 21 and 22: I. INTRODUCTION A study published b
- Page 23 and 24: II. THE PHYSICS BEHIND REMOTE SENSI
- Page 25 and 26: sensitive a given sensor is to diff
- Page 27 and 28: Figure 3. From Green et al. (1998),
- Page 29 and 30: analyzing imagery spectra, it is mo
- Page 31 and 32: After data have been converted to r
- Page 33 and 34: Collins et al. (1997) was able to s
- Page 35 and 36: These purposes include, but are not
- Page 37 and 38: III. DESERT ECOSYSTEM CHARACTERISTI
- Page 39 and 40: sagebrush of Utah, Montana, and the
- Page 41 and 42: in desert regions include argids, o
- Page 43 and 44: 2. Biological Soil Crusts (BSCs) Bi
- Page 45 and 46: 2004), especially in cases where ma
- Page 47 and 48: IV. STUDY SITES The focus area of t
- Page 50 and 51: Figure 13. This figure illustrates
- Page 52 and 53: Following the uplift that occurred
- Page 56 and 57: wavelengths being analyzed to obtai
- Page 58 and 59: 2. Field Spectroscopy An Analytical
- Page 60 and 61: A spectral library was then built a
- Page 62 and 63: after atmospherically correcting th
- Page 64 and 65: where: is the mean corrected and no
- Page 66 and 67: also be seen in Figure 23. The leve
- Page 68 and 69: Figure 24. This figure is a compari
- Page 70 and 71: Figure 25. This figure shows ASD co
- Page 72 and 73: Looking at Figure 25 it is apparent
- Page 74 and 75: A. IMAGERY DERIVED ENDMEMBERS The i
- Page 76 and 77: Figure 28. The above shows some of
- Page 78 and 79: spectrometer, reflectance values we
- Page 80 and 81: such an inference can be made (Ben-
- Page 82 and 83: While this is lower than the hoped
- Page 84 and 85: While the lower value would initial
- Page 86 and 87: Figure 33. This figure shows the ad
- Page 88 and 89: Inset C of Figure 35 is the same da
- Page 90 and 91: However, the presences of BSCs are
- Page 92 and 93: A B C Figure 37. Inset A shows the
- Page 94 and 95: A B C Figure 38. Inset A shows a co
- Page 96 and 97: differences in the studies by other
- Page 98 and 99: small concentrations making them un
- Page 100 and 101: area making it possible to tell wha
- Page 102 and 103: Clark, R. N., Swayze, G. A., Livo,
FLAASH, which supports hyperspectral sensors such as Hyperspectral Mapper<br />
(HyMAP), AVIRIS, Hyperspectral digital Imagery Collection experiment (HYDICE),<br />
and a few o<strong>the</strong>rs as well as multispectral sensors like Advanced Spaceborne Thermal<br />
Emission and Reflection Radiometer (ASTER), is an au<strong>to</strong>mated atmospheric correction<br />
method developed by <strong>Spectral</strong> Sciences Inc. under sponsorship from <strong>the</strong> U.S. Air Force<br />
(Bernstein et al., 2012). FLAASH per<strong>for</strong>ms atmospheric correction on wavelengths in<br />
<strong>the</strong> visible through shortwave infrared regions (up <strong>to</strong> 3000 nm) incorporating Moderate<br />
Resolution Atmospheric Radiance and Transmission Model 4 (MODTRAN4) radiative<br />
transfer code in<strong>to</strong> <strong>the</strong> processing. Options include standard MODTRAN atmosphere and<br />
aerosol types, but FLAASH also allows <strong>for</strong> correction <strong>for</strong> <strong>the</strong> adjacency affect, where<br />
pixel mixing occurs as a result of surface-reflected radiance scattering. An average<br />
aerosol/haze amount can also be calculated <strong>for</strong> <strong>the</strong> scene, and cirrus and opaque clouds<br />
can be masked (Kruse et al., 2004). FLAASH begins with <strong>the</strong> radiance equation at <strong>the</strong><br />
sensor in <strong>the</strong> standard <strong>for</strong>m of<br />
where:<br />
is pixel surface reflectance<br />
is <strong>the</strong> average surface reflectance <strong>for</strong> <strong>the</strong> pixel and <strong>the</strong> surrounding region<br />
is <strong>the</strong> atmosphere’s spherical albedo<br />
La is atmospherically back-scattered radiance<br />
are coefficients dependent on atmospheric and geometric conditions<br />
The values <strong>for</strong> A, B, S, and are determined using MODTRAN4 calculations<br />
that utilize viewing and solar angles and <strong>the</strong> mean surface elevation of <strong>the</strong> measurement.<br />
A model atmosphere, aerosol type, and visible range can be selected. The values <strong>for</strong> A,<br />
B, S, and are heavily dependent on <strong>the</strong> amount of water vapor present. To account <strong>for</strong><br />
this, MODTRAN4 calculations are looped over a column amount series with selected<br />
35<br />
(3)
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