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基于珠海一号高光谱影像的南矶湿地分类

Classification of the Nanji Wetland based on Zhuhai-1 hyperspectral imagery

  • 摘要: 高光谱遥感技术在湿地遥感分类中备受关注,选择合适的特征波段进行湿地分类至关重要。本研究以江西鄱阳湖南矶湿地国家级自然保护区为研究对象,采用珠海一号高光谱数据,分别对水体类、植被类和其他地物类进行光谱特征变换与分析,采用误差范围阈值法对三大类地物进行特征波段筛选,运用马氏距离评估所选特征波段的适用性,并依据不同特征波段的组合对南矶湿地进行随机森林分类。研究结果表明,通过特征优选水体类保留了500 nm和596 nm关键波长,植被类特征向可见光区域偏移,有效捕捉到了“绿峰”与“红边”特性,其他地物类经光谱变换后,波段聚焦于531nm、560nm、596nm等;同类地物经3种特征变换后的特征波段马氏距离值较小;特征组合强化了地物光谱差异,减少了错分漏分现象,原始数据+包络线去除+一阶导数变换特征波段组合的总体分类精度为92.0%,Kappa系数为0.904 6,比原始数据特征波段的总体分类精度和Kappa系数分别提高了42.41%和52.83%。研究结果不仅能够为湿地遥感分类中特征波段的选择提供理论基础,还可为内陆湖泊湿地的识别和监测提供技术参考。

     

    Abstract: Hyperspectral remote sensing technology has garnered significant attention in the field of wetland remote sensing classification. Selecting appropriate characteristic bands is of paramount importance for wetland classification. In this study, the Jiangxi Poyang Lake Nanji Wetland National Nature Reserve was chosen as the study area due to its ecological diversity and representative wetland characteristics. Comprehensive analysis of hyperspectral characteristics for water bodies, vegetation, and other land cover types within the wetland was conducted using hyperspectral data from the Zhuhai-1 satellite. The characteristic bands for these three major terrestrial features were meticulously screened using the error range threshold method, ensuring only the most relevant and distinct bands were selected. The applicability of the selected characteristic bands was rigorously assessed through the utilization of Mahalanobis distance, a statistical measure that quantifies the spectral differences between features. Subsequently, the random forest classification algorithm was applied to the Nanji Wetland based on the optimal combination of different characteristic bands. The research findings indicated that water bodies retained key wavelengths such as 500 nm and 596 nm through feature optimization, while vegetation spectral characteristics shifted towards the visible light region, effectively capturing the "green peak" and "red edge" features. For other terrestrial features, after spectral transformation, the bands were concentrated at 531 nm, 560 nm, 596 nm, etc. For the same type of land features, the Mahalanobis distance values were comparatively small on the feature bands obtained after three kinds of feature transformations. The combination of feature bands significantly strengthened the spectral differences among terrestrial features, reducing misclassification and omission phenomena. Notably, the overall classification accuracy of the combination of original data, continuum removal, and first-order derivative transform feature bands reached 92.0%, with the Kappa coefficient as high as 0.9046, which were 42.41% and 52.83% higher than in terms of overall classification accuracy and Kappa coefficient using the characteristic bands from original data alone, respectively. The research results can not only provide a theoretical basis for the selection of feature bands in wetland remote sensing classification, but also provide technical references for the identification and monitoring of inland lake wetlands.

     

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