XXII ISPRS Congress 2012: Technical Commission VIII

Shortis, M.; Shimoda, H.; Cho, K.

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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:: 1663822514

Title:: Technical Commission VIII

Scope:: 590 Seiten

Year of publication:: 2014

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663822514

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(39,B8)

Language:: English

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

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

Editor:: Shortis, M.; Shimoda, H.; Cho, K.

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:: [VIII/6: Agriculture, Ecosystems and Bio-Diversity]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: SPECTRAL CHARACTERISTICS OF SELECTED HERMATYPIC CORALS FROM GULF OF KACHCHH, INDIA Nandini Ray Chaudhury

Document type:: Multivolume work

Structure type:: Chapter

data usually show spectral mixing of corals and other reef substrates like benthic algae, reef-sand, etc. Therefore, it becomes necessary to understand the spectral behaviour of corals in situ to comprehend space-borne sensor-level signal of corals from a reef. In situ spectral behaviour of Indian corals per se, in visible, near- and mid-infra-red (NIR and MIR) regions of the spectrum was so far unknown. This study attempts to characterize seven, live (belonging to seven genera and four distinctive colony morphologies) and one bleached hermatypic corals from Gulf of Kachchh, India with in situ hyperspectral data over a continuous spectral range of 350 to 1350 nm. 2. STUDY AREA Indian coast is endowed with spatially limited but strategically located coral reef habitats which offer a myriad of marine biodiversity combined with unique regional characteristics. In India, major coral reefs occur in four distinct locations. Two of them occur in gulf settings: Gulf of Kachchh in Arabian Sea and Gulf of Mannar in Bay of Bengal while the other two are off- shore island groups of Lakshadweep in Arabian Sea and Andaman and Nicobar in Bay of Bengal. Indian coral reefs share sixty genera of hermatypic, scleractinian corals out of the one hundred and eleven genera reported in the world (Venkataraman, 2003). Thus, Indian corals share 54% of global coral diversity at genera level. The southern part of Gulf of Kachchh from Gujarat coast represents the sturdiest scleractinian coral species of India. Occurring in the northernmost limits of Indian reef regions (22?20' to 22?40' north latitudes and 68?30' to 70?40' east longitudes), these corals grow in a highly turbid and saline, macro-tidal environment marked with semi-diurnal desiccations due to fluctuating tidal exposures (Navalgund et al. 2010). Out of the sixty genera of scleractinian corals reported from India, only twenty genera are found in Gulf of Kachchh (Venkataraman, 2003) reef region which is declared and protected as a Marine Sanctuary since 1983. A: Location of Gulf of Kachchh in India B: Location of Study Areas: 1 and 2 in Gulf of Kachchh 1: Paga Reef 2: Laku Point > Z IRS P6 LISS-IIF CC Dated: 14'^ February, 2009 ATEM Tu Daterk 16° March, 2005 Figure 1. Location of the study sites Paga reef and Laku Point (near Poshitra) were chosen as two specific sites (Figure 1) for collection of in situ coral spectra from Gulf of Kachchh. These sites had been reported to have relatively high generic diversity of scleractinian corals within the region (Patel, 1978). Moreover the yearly, equinoctial spring tides (negative low tides) result in maximum exposure of inter-tidal and sub-tidal areas of these reefs facilitating in situ coral Spectra collection with virtually no water column. Paga is an off-shore patch reef where diverse coral colonies occur mostly in the reef slope, reef crest and outer reef flat areas while Laku point is à narrow fringing reef where coral colonies grow in shallow, rock. pools. 3. MATERIAL & METHODS 3.1 Multi-spectral Signatures of Reef Substrates from Resourcesat-1 LISS-IV Data Linear Imaging and Self Scanning sensor: LISS-IV, onboard Resourcesat-1 (IRS-P6) and 2 (RS2) satellites have been the most preferred imaging sensor for Indian coral reefs for its high spatial resolution (5.8 m at nadir) complemented with three spectral channels (located in Green, Red and NIR regions) and 10 bit level of quantization. LISS-IV in multi-spectral mode has performed considerably well to characterize reef geomorphology of the smaller reefs of Central Indian Ocean (Navalgund et al. 2010). However, at an orbital altitude of 817 km, detection capability of this sensor gets spatially limited for coral colonies within a reef. Three discrete, broad-band, spectral channels, positioned at 530 to 590 nm, 620 to 680 nm and 770 to 860 nm usually fall short to spectrally resolve a “pure coral signature”. Cohabitation of macro reef-benthos like corals and macro-algae along with underlying litho-substrates (sand, mud, etc.) under varying depths of water column make this task all the more difficult. Atmospheric interferences also alter the strength of the back-scattered signal through atmospheric absorption and scattering. The back scattered signal from a reef for a single pixel can thus be a mixed representation of the natural heterogeneity present in the corresponding reef area. This problem has been demonstrated with the help of Figures 2 and 3 as a case study using a subset of an archived IRS- P6 LISSIVMX (multi-spectral) data acquired on 16" March, 2005 pertaining to Paga reef. The spectral behaviour of selected reef substrates have been analysed with respect to Top of the earth's Atmosphere (TOA) spectral radiance. No atmospheric correction has been performed on this subset image for this study. Figure 3 shows multi-spectral signatures (in terms of mean spectral radiance of randomly selected thirty pixels for each group) of five distinct reef categories obtained from the subset of LISS-IVMX image of Paga reef (Figure 2). This subset image was digitally enhanced by applying standard deviation stretch for better visual appreciation of the reef substrates. Four out of the selected five pixel-groups which represent four different reel substrates are clearly, visually distinguishable by their respective tones. In a standard LISS-IVMX False Colour Composite (FCO: white pixels representing pure, exposed sand get well distinguished from rest of the reef pixel classes, as à substrate giving the highest spectral response in all the three channels. For Paga reef the submerged sand pixels on reef flat (free of any kind of benthic substrates) appeared in light green tone as the sand is mixed with silt and clay. LLL————— Figure 2. A an The effect of substrates fro values of m represented (chlorophycez can be differe brown colou dominates the Figure 3. The minimal in the the green ban increase in th nm) this diffe Figure 3. The fifth pp different tone: flat’ zone of I by diverse 1 colonies. The ‘rough text chlorophycea mean spectral centre of th difference in : algae categori Vis cyan and | is replaced by vertical dista response due Thus, in NIF within the phyaophyceac Macro-alga cc pixels. This f spectral radia; Phyaophycea: Signal in g phyaophyceag outline trian; reaffirms the band, multi-s Coral colonies

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