XXII ISPRS Congress 2012: Technical Commission VII

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Multivolume work

Persistent identifier:: 1663813779

Title:: XXII ISPRS Congress 2012

Sub title:: Melbourne, Australia, 25 August-1 September 2012

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663813779

Language:: English

Additional Notes:: Kongress-Thema: Imaging a sustainable future

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1663821976

Title:: Technical Commission VII

Scope:: 546 Seiten

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663821976

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(39,B7)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist ermittelt.; Literaturangaben

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [VII/1: PHYSICAL MODELLING AND SIGNATURES IN REMOTE SENSING]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: SENSITIVITY ANALYSIS IN THE RETRIEVAL OF TURBID COASTAL WATER BATHYMETRY USING WORLDVIEW-2 SATELLITE DATA S. C. Liew, C. W. Chang, L. K. Kwoh

Document type:: Multivolume work

Structure type:: Chapter

International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012 XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia The second component is related to the seabed reflectance pp O-) modelled by, PppA) = AP), (4) where Q(A) is the reflectance spectrum of a typical sandy bed normalized such that p(555nm)=1 and 4 is the seabed albedo at 555 nm. 3 n Fh "Coastal" 3 A i o 0.9 : — Blue g 0.8 3 PO Green a 0 3 2 a Yellow gi — Red = 05 € 3 os J wenn "Red Edge" 9 e m —NIR1 ^ 94 : ——NIR2 > 03 = N 202 - e 0.1 s = | | dre écran ++ 350 450 -550 650 750 850 950 1050: 1150 Wavelength (nm) Figure 1. The relative spectral response curves of the 8 multispecral bands of the World View-2 satellite sensor. Bae Band Name en Bandwidth (nm) (nm) 1 “Coastal” 429.3 47.3 2 Blue 478.8 54.3 3 Green 547.5 63.0 4 Yellow 607.8 37.4 5 Red 658.5 37.3 6 “Red Edge” 723.5 39.3 7 NIR 1 825.0 98.9 8 NIR2 919.4 99.6 Table 1. Effective wavelengths and bandwidths of the WorldView-2 spectral bands. The other parameters common to both components in the equation (1) are the water depth H, effective attenuation coefficient K K(X) 2 a(4) * by.) , (5) and the geometric path length factor M, M =1/cos0, +1/cos6,, (6) where 0, .0, are respective the in-water sensor view angle and solar zenith angle. The absorption and backscattering coefficients of water is a linear combination of various optically active constituents. by 0.) - bp) - bp 0) aA) =a, (MN) + ag (X) aq (X) (7) (8) where the subscripts w, g, p and ¢ refer to water, coloured dissolved organic matter (CDOM) and phytoplankton respectively. The absorption and backscattering coefficients of each component are computed according to the commonly used bio-optical models (Lee et al., 1999), with the following water quality parameters: G (CDOM absorption coefficient at 440 nm), X (particulate matter backscattering coefficient at 550 nm), and P (phytoplankton absorption coefficient at 440 nm). The above water reflectance can then be calculated according to (Lee et al., 2002), 0.52550) Rs (A) = 9 A 1-1.755 (4) 9 The in-band effective reflectance of each WorldView-2 spectral band is computed by aggregating the above-water spectral reflectance R,;(A) using the respective relative spectral response function S;(A) and the solar flux density F(A), J SjQQFQ)R, Q.) à cad R (10) Ay [$;Q)FQ.) dA ^ where the subscript / is the band number. The lower and upper wavelength limits of integration are, respectively, A; =380nm and À, =1100nm. 4 RESULTS The in-band effective reflectance of coastal sea water was calculated for each of the first six WorldView-2 spectral bands using equations described in the previous section. The values of the water quality parameters were set to G=04 mi. 1 Xz0.1m . Phytoplankton is assumed to be absent, i.e. P -0m'!. These are the typical values for coastal waters in the Singapore Strait southwest of the Singapore main island. The path length parameter was set at M =2.1 and the reflectance was calculated for water depth varying from 0.1 m to 10 m. Two values of the seabed albedo, 4-0 and A=0.2 were used, representing cases with a dark (muddy) and bright (sandy) sea bottom respectively. Figure 2 shows the typical reflectance spectrum of coastal sea water with a bright sandy sea bottom and water depth H — 2 m. The solid line is the computed reflectance spectrum (equation 9) while the red circles are the in-band effective reflectance of the eight WorldView-2 spectral bands (equation 10) plotted at their respective effective wavelength (Table 1). The in-band reflectance values of coastal sea water with a dark seabed for the first 6 spectral bands of WorldView-2 are plotted as functions of the water depth in Figure 3. The reflectance generally increases monotonically with water depth for all the spectral bands plotted. The Green band (Band 3) has the highest reflectance and the reflectance values fall off at shorter and longer wavelengths. The reflectance seems to saturate (i.e. does not change with increasing water depth) after a certain threshold depth. This threshold depth is a function of the spectral band.

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