| Analysis on coral reefs mapping using SPOT5 data at the Dongsha Atoll |
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| 作者姓名： | CHEN Jianyu MAO Zhihu ZHANG Huaguo WU Junping CHEN Xiaodong PAN Delu |
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| 作者单位： | CHEN Jianyu1，MAO Zhihua1，ZHANG Huaguo1，WU Junping1，CHEN Xiaodong1，PAN Delu11. State Key Laboratory of Satellite Ocean Environment Dynamics，Second Institute of Oceanography，State Oceanic Administration，Hangzhou 310012，China |
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| 基金项目： | 国家自然科学基金
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The Chinese Offshore Investigation and Assessment
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Chinese Offshore Investigation and Assessment |
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| 摘 要： | Coral reefs are an sensitive-to-environment complex marine ecosystem. The ecosystem of corals is rich in biodiversity. Remote sensing offers a powerful tool for categorizing coral reefs and is the most cost-effective approach for the large-scale reef survey. The Dongsha Atoll, more than 300 km2 with an average depth of 10 m, is located at the northern continental margin of the South China Sea. It has been abused by destructive fishing during recent decades. Three satellite imageries (Quickbird2, ETM and SPOT5) are used to evaluate the capabilities of SPOT5 imagery to provide data that are useful for categorizing the current distribution of coral reefs therein. During the data processing, unsupervised classification functions are adopted for ETM and SPOT5 data, while the supervised classification method is used for Quickbird2. The classes are (or not) merged into coral reef, and then will be operated by vectorization, simplification, and topological analysis. There are 1 331 coral reefs larger than 100 m2 with a detection limit of 3×3 pixels at the multi-band data of Quickbird2, which is taken as the comparison baseline. The results extracted from SPOT5 and ETM images are less in number and area than those from the Quickbird2 image, whereas the results from SPOT5 data are better than those of ETM data at the silty lagoon due to its higher resolution. SPOT5 XS band 2 fails to distinguish the deep substrate inside the atoll compared with ETM data because of its poor penetration capability. Only SPOT XS band 1 cannot be used to differentiate coral reef from sand bottom. Merging the SPOT5 multi-bands data with the spatial resolution of SPOT5 pan-data and referring to ETM imagery are expected to provide an optimal satellite-based approach for mapping of coral reefs.
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| 关 键 词： | 珊瑚岛 东沙环礁 遥感图象 成像分析 SPOT5数据 |
| 收稿时间： | 2006-06-27 |
| 修稿时间： | 2006-10-15 |
Analysis on coral reefs mapping using SPOT5 data at the Dongsha Atoll |
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| CHEN Jianyu,MAO Zhihu,ZHANG Huaguo,WU Junping,CHEN Xiaodong,PAN Delu.Analysis on coral reefs mapping using SPOT5 data at the Dongsha Atoll[J].Acta Oceanologica Sinica,2007,26(2):26-35. |
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| Authors: | CHEN Jianyu MAO Zhihu ZHANG Huaguo WU Junping CHEN Xiaodong and PAN Delu |
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| Institution: | State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China |
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| Abstract: | Coral reefs are an sensitive-to-environment complex marine ecosystem. The ecosystem of corals is rich in biodiversity. Remote sensing offers a powerful tool for categorizing coral reefs and is the most cost - effective approach for the large - scale reef survey. The Dongsha Atoll, more than 300 km2 with an average depth of 10 m, is located at the northern continental margin of the South China Sea. It has been abused by destructive fishing during recent decades. Three satellite imageries (Quickbird2, ETM and SPOTS) are used to evaluate the capabilities of SPOT5 imagery to provide data that are useful for categorizing the current distribution of coral reefs therein. During the data processing, unsupervised classification functions are adopted for ETM and SPOT5 data, while the supervised classification method is used for Quickbird2. The classes are (or not) merged into coral reef, and then will be operated by vectorization, simplification, and topological analysis. There are 1 331 coral reefs larger than 100 m2 with a detection limit of 3 × 3 pixels at the multi - band data of Quickbird2, which is taken as the comparison baseline. The results extracted from SPOT5 and ETM images are less in number and area than those from the Quickbird2 image, whereas the results from SPOT5 data are better than those of ETM data at the silty lagoon due to its higher resolution. SPOT5 XS band 2 fails to distinguish the deep substrate inside the atoll compared with ETM data because of its poor penetration capability. Only SPOT XS band 1 cannot be used to differentiate coral reef from sand bottom. Merging the SPOT5 multi - bands data with the spatial resolution of SPOT5 pan - data and referring to ETM imagery are expected to provide an optimal satellite - based approach for mapping of coral reefs. |
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| Keywords: | coral reef Dongsha Atoll SPOT5 Quickbird2 |
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