基于作物双时相遥感特征的花生种植区提取

Extraction of Peanut Planting Area Based on Dual-temporal Remote Sensing Features of Crops

  • 摘要: 基于花生生长中后期2020年8月1日和15日两个时相高分多光谱数据,构建40个作物分类遥感特征,采用ReliefF-Pearson方法优选出15个特征,构造作物可分的4种特征空间。采用最大似然分类法、支持向量机和随机森林分类器,分别耦合4种特征空间,开展作物分类对比试验,进行分类精度和景观评价提出作物双时相遥感分类模型(dual-temporal remote sensing classification model for crop, C-DRSC)。结果表明:该模型具有较高的作物分类和花生识别能力,作物分类总体精度和Kappa系数分别为93.25%和0.89,平均形状指数和平均斑块分维指数分别为1.33和1.13;花生识别的用户精度和制图精度分别为96.20%和96.32%,平均形状指数和平均斑块分维指数分别为1.27和1.11。利用该模型在黄淮海地区的4个花生主产县开展夏花生种植面积遥感测算,与统计面积相比,面积测算相对误差为±16.25%,决定系数为0.9778(达到0.01显著性水平),模型具有较好的适用性。

     

    Abstract: Various high-resolution satellite remote sensing platforms and sensors have been established recently, but there are still many challenges for crop type fine classification. New methods are needed for fine classification of crop types and extraction of peanut planting area using high-resolution optical remote sensing data. Using panchromatic and multi-spectral (PMS) data of GF-1 and GF-6 in the middle and late stages of crop growth, 40 classification features are constructed from the perspective of spectrum, texture, and temporal variation of remote sensing image by means of spatio-temporal fusion and spectral mathematical transformation.15 features are selected by ReliefF-Pearson method. To compare the effects of different feature types on classification, the selected features are combined into four feature spaces, and the separability between crops in these feature spaces is measured by Jeffries-Matusita (J-M) distance. Using maximum likelihood classification, support vector machine and random forest as classifiers, crop classification tests of four feature space schemes are carried out, and different classification results are evaluated from the perspective of remote sensing classification accuracy and landscape analysis. Compared with the original image, in four feature spaces, the J-M distance between peanut and other crops is close to the saturation value of 2.0, and their separability is significantly enhanced. For all test results, the overall accuracy of crop classification is more than 78.0%, the Kappa coefficient of crop classification is more than 0.7, and the user's accuracy and producer's accuracy of peanut are both more than 79.0%. Compared with the three classifiers, Random Forest has the highest classification accuracy, and the average values of the overall accuracy and Kappa coefficient, peanut user's accuracy and producer's accuracy of its four schemes are 91.49%, 0.89, 94.45% and 93.30%, respectively. In addition, combining dual-temporal remote sensing data, texture and vegetation index features, as well as their temporal changes, can effectively improve the classification accuracy. It shows that adding the texture feature can improve the accuracy better than the vegetation index features. The landscape shape analysis of the classification results also shows that the overall crop classification and peanut, their patch shapes are close to the reality, and random forest is the best classifier. Its mean shape indices of crop landscape-level and peanut class-level are only 1.333 and 1.270, and the corresponding mean patch fractal dimension indices are only 1.127 and 1.110. An optimal dual temporal remote sensing crop classification model is proposed. Using this model, summer peanut planting area extraction and area measurement are carried out in four main peanut producing counties in Huang-Huai-Hai Region. Compared with the statistical data, the determination coefficient is 0.98 and the relative error of area calculation is ±16.25%, showing a good application prospect.

     

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