Ground-level spectroscopy analyses and classification of coral reefs using a hyperspectral camera

Caras, Tamir; Karnieli, Arnon

doi:10.1007/s00338-013-1033-1

Cited by 8 publications

(8 citation statements)

References 46 publications

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“…The relationship between integrated reflectance and symbiont concentration may prove useful to assess or monitor reef condition and the potential for bleaching. Such algorithms may be implemented using hyperspectral sensors from airborne platforms like the Portable Remote Imaging Spectrometer (PRISM) [1,38], proposed future satellite sensors, and through the use of underwater hyperspectral imagers [32,33,47,48]. However, the implementation of the algorithms will be complicated by the effects of the intervening water column, sea-surface, and atmosphere, as well as the spectral and spatial resolution of the sensor itself [24,35].…”

Section: Conclusion and Outlook For Remote Sensingmentioning

confidence: 99%

Spectral Reflectance of Palauan Reef-Building Coral with Different Symbionts in Response to Elevated Temperature

et al. 2016

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Spectral reflectance patterns of corals are driven largely by the pigments of photosynthetic symbionts within the host cnidarian. The warm inshore bays and cooler offshore reefs of Palau share a variety of coral species with differing endosymbiotic dinoflagellates (genus: Symbiodinium), with the thermally tolerant Symbiodinium trenchii (S. trenchii) (= type D1a or D1-4) predominating under the elevated temperature regimes inshore, and primarily Clade C types in the cooler reefs offshore. Spectral reflectance of two species of stony coral, Cyphastrea serailia (C. serailia) and Pachyseris rugosa (P. rugosa), from both inshore and offshore locations shared multiple features both between sites and to similar global data from other studies. No clear reflectance features were evident which might serve as markers of thermally tolerant S. trenchii symbionts compared to the same species of coral with different symbionts. Reflectance from C. serailia colonies from inshore had a fluorescence peak at approximately 500 nm which was absent from offshore animals. Integrated reflectance across visible wavelengths had an inverse correlation to symbiont cell density and could be used as a relative indicator of the symbiont abundance for each type of coral. As hypothesized, coral colonies from offshore with Clade C symbionts showed a greater response to experimental heating, manifested as decreased symbiont density and increased reflectance or "bleaching" than their inshore counterparts with S. trenchii. Although no unique spectral features were found to distinguish species of symbiont, spectral differences related to the abundance of symbionts could prove useful in field and remote sensing studies.

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Section: Conclusion and Outlook For Remote Sensingmentioning

confidence: 99%

Spectral Reflectance of Palauan Reef-Building Coral with Different Symbionts in Response to Elevated Temperature

et al. 2016

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“…As for the examples above, substrate complexity was simplified to the extent that most of the pixels did contain only one substrate (e.g., 4 key classes at [18]. Moreover, unlike the previous attempt by Caras and Karnieli [26], the classification model tested here is an amalgamation of substrates collected from three images and applied to all three. Subsequently, the study focused on which classification system is the best suited for this task.…”

Section: Discussionmentioning

confidence: 99%

“…That meant that water correction is small and can be applied to the entire image uniform. Based on these initial assumptions, image water correction relied on underwater reef-level white referencing plate and a dark object to undertake standard empirical line correction [26]. Dividing the image by an extract (spectrum from an averaged area of interest (AOI)) of the underwater white reference plate converts all values into reflectance [44,45].…”

Section: Image Pre-processingmentioning

confidence: 99%

“…Another complementary solution is data combinations from different sources (e.g., [3,13,24,25]). Recently, a variety of advanced statistical approaches based on spectral techniques have been employed [3,13,25,26].…”

Section: Introductionmentioning

confidence: 99%

“…In comparison to the previous attempt at ground-based hyperspectral imagery [26], the current study presents an improved approach for classification, namely the Partial Least Squares-Discriminant Analysis (PLS-DA) procedure. The PLS-DA procedure is particularly suited to handling hyperspectral data, and is based on dimensionality reduction products, such as principle component analysis (PCA) [32,33].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ground-Level Classification of a Coral Reef Using a Hyperspectral Camera

Caras

Karnieli

2015

Remote Sensing

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Especially in the remote sensing context, thematic classification is a desired product for coral reef surveys. This study presents a novel statistical-based image classification approach, namely Partial Least Square Discriminant Analysis (PLS-DA), capable of doing so. Three classification models were built and implemented for the images while the fourth was a combination of spectra from all three images together. The classification was optimised by using pre-processing transformations (PPTs) and post-classification low-pass filtering. Despite the fact that the images were acquired under different conditions and quality, the best classification model was achieved by combining spectral training samples from three images (accuracy 0.63 for all classes). PPTs improved the classification accuracy by 5%-15% and post-classification treatments further increased the final accuracy by 10%-20%. The fourth classification model was the most accurate one, suggesting that combining spectra from differ conditions improves thematic classification. Despite some limitations, available aerial sensors already provide an opportunity to implement the described classification and mark the next investigation step. Nonetheless, the findings of this study are relevant both to the field of remote sensing in general and to the niche of coral reef spectroscopy.

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Remote Sensing for Marine Management

Fingas

2019

World Seas: An Environmental Evaluation

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Ground-level spectroscopy analyses and classification of coral reefs using a hyperspectral camera

Cited by 8 publications

References 46 publications

Spectral Reflectance of Palauan Reef-Building Coral with Different Symbionts in Response to Elevated Temperature

Spectral Reflectance of Palauan Reef-Building Coral with Different Symbionts in Response to Elevated Temperature

Ground-Level Classification of a Coral Reef Using a Hyperspectral Camera

Remote Sensing for Marine Management

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