| Popis: |
Coral reefs are referred to as "tropical rainforests of the sea" to provide for richness of biological diversity. However, coral reefs are seriously degrading for global warming effects. Mapping coral reefs is important to spatially interpret the current coral distribution. Now, coral reefs mapping is generally created by visual interpretation with aerial photos in Japan. For effectively mapping coral reefs cover, the study is to understand availability if satellite-based remote sensing technique is able to be substituted in the near future. The paper introduces how to map coral reefs distribution by aerial photo-based visual interpretation and satellite-based analytical process. The result by satellite data is evaluated with the ground truth data and the visible interpretation method. In the error matrix utilizing 73 ground survey points, the overall accuracy was achieved 78%, which indicated similar trend with the ground truth. In error matrix with rasterized visible interpretation map, the overall accuracy was 55%. The reason is why "less than 5% Coral cover on Sand and Rock bottom" and "5–50% Coral cover" were caused misclassification in the offshore. However, the inshore area in the analytical result is able to detail coral structure, and the satellite image was able to penetrate deeper by the water column correction. Therefore, satellite-based remote sensing is appreciable to apply for the coral reefs mapping. In the future, we need to consider the classification class types and pro-processing to achieve higher accuracy. |
