Habitat map of Danajon Bank, Philippines, derived from a high-spatial-resolution multi-spectral satellite image and georeferenced point intercept transect and spot-check survey field data, using an object-based image classification method

A mosaic of two WorldView-2 high resolution multispectral images (Acquisition dates: October 2010 and April 2012), in conjunction with field survey data, was used to create a habitat map of the Danajon Bank, Philippines (10°15'0'' N, 124°08'0'' E) using an object-based approach.
To create the habitat map, we conducted benthic cover (seafloor) field surveys using two methods. Firstly, we undertook georeferenced point intercept transects (English et al., 1997). For ten sites we recorded habitat cover types at 1 m intervals on 10 m long transects (n= 2,070 points). Second, we conducted geo-referenced spot check surveys, by placing a viewing bucket in the water to estimate the percent cover benthic cover types (n = 2,357 points). Survey locations were chosen to cover a diverse and representative subset of habitats found in the Danajon Bank. The combination of methods was a compromise between the higher accuracy of point intercept transects and the larger sample area achievable through spot check surveys (Roelfsema and Phinn, 2008, doi:10.1117/12.804806).
Object-based image analysis, using the field data as calibration data, was used to classify the image mosaic at each of the reef, geomorphic and benthic community levels. The benthic community level segregated the image into a total of 17 pure and mixed benthic classes.

本研究采用两景2010年10月与2012年4月获取的WorldView-2高分辨率多光谱影像镶嵌图（WorldView-2），结合野外调查数据，以面向对象影像分析方法（object-based image analysis）绘制菲律宾达纳琼滩（地理坐标：10°15'0'' N, 124°08'0'' E）的生境地图。
为绘制该生境地图，本研究采用两种方法开展底栖覆盖（海底）野外调查：其一为地理参考点截样带法（English等，1997），在10个调查点位沿10米长样带以1米间隔记录生境覆盖类型，共获取2070个测点（n=2070）；其二为地理参考现场抽查法：将水下观测桶置入水中，以此估算底栖覆盖类型的百分比占比，共获取2357个测点（n=2357）。调查点位的选取覆盖了达纳琼滩内多样且具有代表性的生境类型。两种方法的结合兼顾了点截样带法的高精度与抽查法可获取更大样本区域的优势（Roelfsema与Phinn，2008，doi:10.1117/12.804806）。
本研究以野外调查数据作为校准数据，采用面向对象影像分析方法，分别在珊瑚礁、地貌与底栖群落三个层级对影像镶嵌图进行分类。其中底栖群落层级将影像划分为共计17种纯底栖类与混合底栖类。