基于最大类间方差法和数学形态学的遥感图像潮沟提取方法

潮沟作为潮滩的主要地貌类型之一,以长江口九段沙为研究对象,利用2015年2月15日获取的Landsat 8分辨率为15 m的全色波段遥感数据为数据源,选取了3条发育不同的潮沟。首先利用顶帽变换来消除直接利用最大类间方差法对图像亮度背景不均匀不能准确分割的问题,然后通过最大类间方差法找到一个最佳的阈值使潮沟和背景之间方差最大,得到二值化图像;接着通过形态膨胀对断裂的潮沟进行连接,并用形态去除方法剔除非目标;最后对潮沟进行骨架化提取和去除短枝处理,得到完整的潮沟信息骨架图。采用视觉分析和定量分析对提取的潮沟信息进行精度评价。结果表明,最大类间方差法和数学形态学的结合对潮沟信息提取有较好的效果,平均准确度达到93.0%,遗漏误差和冗余误差分别为7.0%和0.5%。

Remote sensing image extraction of tidal channels based on Otsu and mathematical morphology

Tidal channel is one of the major tidal flat landforms. The Jiuduan Shoal in Yangtze River Estuary was taken as the object in this paper. Three different types of tidal channels in panchromatic band remote sensing data received from Landsat 8 satellite on February 15, 2015 were selected. Firstly, the top-hat transformation is to eliminate the problem of the backgrounds of uneven brightness accurately, if the method of maximum between-class variance(Otsu) is used directly; Then, Otsu is used to find an optimal threshold to make the maximum variance between tidal channel and background, obtaining a binary image; Thirdly, the broken tidal channel is connected by morphological dilation, and non-target is removed by morphological removal. Finally the skeleton of tidal channel is extracted and cropped, and the complete information of tidal channel is gained. Visual analysis and quantitative analysis are used to evaluate the accuracy of the information of tidal channel. The result shows that the method combining Otsu with mathematical morphology can be used to extract tidal channel information efficiently. The average accuracy can reach 93.0%, missing error and redundance error are 7.0% and 0.5% respectively.