融合尺度注意力机制的高分辨率遥感影像水体提取网络

Water Extraction of High Spatial Resolution Remote Sensing Image Fusing Scale Attention Mechanism

  • 摘要: 近年来,水资源短缺等一系列问题日益严重,需要对水资源的数量和变化进行及时准确的监测。从遥感影像上提取的水体信息不仅可以为水体生态分析和后续的相关风险预警提供数据支撑,还可以用于缓解日益严峻的生态环境问题,并有助于所研究流域的环境演变监测、水资源保护和开发以及生态资源的可持续发展。随着机器学习和人工智能的发展,基于机器学习的水体提取方法应运而生,特别是深度学习方法具有强大的特征表征能力,它的发展给计算机视觉和影像识别等领域带来了巨大的冲击。全卷积神经网络(fully convolutional networks, FCN)作为第一个端到端的像素级预测的全卷积网络,拉开了像素级别的语义分割序幕,其他语义分割模型都是在其基础之上发展起来的。然而,在利用FCN及其变种方法进行水体提取时仍然普遍存在水陆边界不清晰等问题。针对上述问题,提出了融合尺度注意力机制的高分辨率遥感影像水体提取加权FCN(squeeze-and-excitation weighted FCN,SE-wFCN)。该方法将注意力机制应用于不同层次或尺度的语义信息来更好地融合不同层次或尺度的特征,尽可能地减少水体边界像素的误分和漏分;考虑到FCN模型的复杂性和过拟合等问题,在FCN中引入辅助分类器,进一步降低深度学习模型在学习训练阶段过拟合发生的可能性;顾及水陆边界的像素位置信息对水体提取的重要性,在损失计算中,对水体边界像素与水体内部像素的损失赋予不同的权重,引导尺度注意力机制和FCN模型更好地关注并学习水陆边界的特征信息,进而可以进一步地提高水陆边界的提取精度。以高分辨率高分一号卫星遥感影像为研究对象,将该网络与目前主流的语义分割网络进行了对比实验,结果表明,SE-wFCN比当前主流的方法(如DeepLabV3、U-Net、U2Net、MECNet、MSResNet和SADA-Net等)在水陆边界上取得了更加满意的水体提取结果。

     

    Abstract:
    Objectives Recently, it is gradually becoming important to timely monitor the accurate distribution and change of water resource on the earth due to the shortage of water resource globally. Water extraction from remotely sensed image not only is able to provide data support for water ecosystem analysis and risk prediction, but also can alleviate the currently serious ecosystem environment and contribute to sustainable development of water resource and environment protection. Because of its powerful feature representation, deep learning has an important influence on computer vision and image recognition domains. Fully convolutional networks (FCN) is the first end-to-end fully convolutional network for image pixel-wise prediction and starts the image semantic segmentation. Hereafter, other variants of image semantic segmentation based on FCN are also put up. However, the border region between water and land is still misclassified during water extracting based on FCN or its variants. Therefore, we put up water extraction of high spatial resolution remotely sensed image fusing scale attention mechanism based on squeeze-and-excitation weighted FCN (SE-wFCN).
    Methods We utilize GF-1 remotely sensed image to do some experiments by comparing with FCN and its variants. The proposed method has the following contribution of three aspects: (1) In order to take advantage of attention mechanism, this method applies it to features of different scales and then fuses those features more reasonably and more scientifically to reduce the possibility of misclassification of water pixels as far as possible. (2) Due to the model complexity of FCN and its possibility of overfitting, we add one auxiliary classifier module to FCN model as one branch during the training phase, which is able to help to reduce the possibility of overfitting. (3) Considering that the border pixel's position between water and land is very important to water extraction and the position information is actually ignored when computing the loss during training phase, we pay more attention to the border pixel by putting more weight in the loss function.
    Results Experimental analysis shows that the proposed method is feasible and effective.
    Conclusions It can achieve the more satisfying of water extraction than these current popular deep learning models (i.e. DeeplLabV3, U-Net, U2Net, MECNet, MSResNet and SADA-Net), especially in the border between water and land.

     

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