基于MODIS地表反射率数据的水体自动提取研究

应用阈值法对遥感图像上的水体目标进行提取时,水陆分割阈值的确定是其难点。以MODIS地表反射率数据为数据源,首先统计大量MODIS地表反射率影像第6波段的水陆分割阈值的范围作为先验阈值范围;然后将历史存档的研究区水体边界矢量叠加到图像上,并且将矢量边界向外扩大一倍,使得扩大后的范围内的水体和陆地面积相当;最后统计扩大后区域的第6波段的灰度直方图,并寻找先验阈值范围内的最小值作为最佳的水陆分割阈值进行水体提取。克服了统计直方图双峰谷值作为分割阈值的传统方法容易受到地物复杂性及噪声影响的难题,使得水陆分割阈值的确定变得更加简单、高效,实现了针对遥感影像上水体目标的自动提取,大大提高了水体提取的效率。

A Study of Extracting Water Bodies Automatically based on the MODIS Surface Reflectance Data

It is always difficult to find a proper threshold that used to the segmentation of remote sensing images to extract water bodies.Choosing the MODIS surface reflectance data as data source,the specific procedures for extracting water bodies are as follows:①Record many thresholds of 6th band of the MODIS surface reflectance data that used to segment the images to extract the water bodies,and then a prior threshold range can be obtained;②Expand the vector boundaries of the water bodies to make land and water have approximately the same areas;③Get the grey level histograms of the expanded regions and select the minimum values between the prior threshold range as the best thresholds to extract different water bodies.It is simply and efficiently to get the suitable thresholds to extract the water bodies with this method,and at the same time it can get rid of influences of complexity of surface features and image noise.Also,it is possible to automatically and very timesaving extract water bodies on remote sensing images.