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    基于卷积神经网络的高分二号影像林分类型分类

    Convolutional neural network for GF-2 image stand type classification

    • 摘要:
      目的基于遥感影像的林分类型分类在现代林业中是一项重要的应用。本文试图构建一个基于高分二号(GF-2)影像林分类型分类的卷积神经网络(CNN)模型,探索CNN在遥感图像像素级分类这一领域的发展潜力。
      方法以GF-2卫星遥感影像为数据源,利用Tensorflow(一种开源用于机器学习的框架)构建4种不同图像斑块大小(m = 5,7,9,11)为输入的CNN,同时以传统的神经网络模型——多层感知器(MLP)为基准,比较不同图像斑块大小下的CNN分类图的分类效果和分类精度。
      结果实验分类结果表明:CNN(m = 9)得出最高的分类精确度,总体精度比MLP和CNN(m = 5,7,11)分别高出10.91%和6.55%、1.3%、2.54%。分类图的可视化结果也表明CNN(m = 9)更好地解决了“椒盐现象”与过度平滑后的边界不确定性问题。
      结论CNN能够在利用高分影像光谱特征的同时充分挖掘影像的空间特征,从而提高分类精度,同时在利用CNN基于遥感影像分类时,根据数据源以及地物的特点选择合适的图像斑块大小作为输入是提高分类精度与分类效果的关键措施。

       

      Abstract:
      ObjectiveThe classification of stand type based on remote sensing imagery is an important application in modern forestry. In recent years, many studies have explored this territory using multiple data sources and classification algorithm. Convolutional neural network (CNN), a new neural network algorithm, has higher accuracy in pattern recognition, scene classification and objective detection because of its unique structure and deep learning technology. The purpose of this paper is to propose a convolutional neural network system tailored for GF-2 (a high-resolution multispectral remote sensing data) applied in stand type classification on pixel-level.
      MethodWe chose different image patch size (i.e. m = 5, 7, 9 and 11) for building CNN and multilayer perceptrons (MLP) as benchmark in tensorflow (an open source library of machine intelligence), to train and compare classification accuracy of model.
      ResultExperimental results showed that the CNN (m = 9) outperformed MLP and CNNs (m = 5, 7 and 11) by 10.91%, 6.55%, 1.3% and 2.54%, respectively, in overall classification accuracy. And the CNN (m = 9) alleviates the effect of salt-and-pepper and boundary uncertainties greatly in visual assessment.
      ConclusionCNN can fully exploit the spatial features of images while utilizing the spectral features of high-resolution images to improve classification accuracy. And on remote sensing image classification based on CNN, selecting the appropriate image patch size according to the data source and the features of the objective is the key measure to improve the classification accuracy and classification effect.

       

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