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    结合多尺度纹理特征的高光谱影像面向对象树种分类

    Object-oriented tree species classification with multi-scale texture features based on airborne hyperspectral images

    • 摘要:
      目的基于机载高光谱影像的分类研究中,利用不同尺度纹理特征与面向对象分类相结合的方法在树种分类的研究中应用较少,并且相关研究主要针对单一树种识别而不考虑多种树种,因此对于复杂林分中的树种识别能力有待进一步研究。本研究拟探究不同尺度纹理特征结合面向对象的分类技术在树种精细分类中的应用效果。
      方法利用机载高光谱数据进行面向对象的树种精细分类。根据研究区内地表类型情况,采用分层分类的方法区分非林地、其他林地与有林地,对有林地进行树种的精细分类。从机载高光谱图像中提取特征变量,包括独立主成分分析ICA变换光谱特征以及空间纹理特征,分析各树种的光谱反射率及所适合的纹理尺度,依据不同尺度纹理特征进行分层分类,比较不同特征利用支持向量机SVM分类的树种分类结果。
      结果结合单一尺度纹理特征的分类结果总体精度为87.11%,Kappa系数为0.846;结合不同尺度纹理特征的分类总体精度为89.13%,Kappa系数为0.87,相比于仅利用光谱特征的分类精度分别提升了4.03%和6.05%。说明在面向对象的分类中,纹理特征的加入对于提升树种分类的精度具有显著效果。结合不同尺度纹理特征的树种分类精度要高于单一尺度纹理特征的分类精度,尤其在其他阔叶树种和马尾松树种的分类中,制图精度较单一纹理尺度分别提高了5.48%和6.12%。
      结论利用不同尺度的纹理特征分类比单一尺度纹理特征分类更具优势,提高了纹理特征在树种分类中的贡献率;综合利用机载高光谱影像的光谱特征和不同尺度纹理特征的面向对象分类方法,使得树种识别更为精细和准确。该方法对于复杂林分树种的分类是有效的,能够满足机载高光谱影像树种精细识别的应用需求。

       

      Abstract:
      ObjectiveBased on the classification of airborne hyperspectral imagery, the method of combining different scale texture features with object-oriented classification was less applied to the classification of tree species, and the related research was mainly for single tree species identification without considering multiple tree species, therefore, the ability to identify tree species in complex forests needs further study. However, the study in such research was scanty, so this study intended to explore the application of different scale texture features and object-oriented classification techniques in the fine classification of tree species.
      MethodWe used airborne hyperspectral data with object-oriented classification to classify tree species. According to the type of land cover in the study area, we used stratified classification method to distinguish non-forest land, other forest land and forested land, and finely classify tree species in forest land. Feature variables were extracted from airborne hyperspectral images, including independent component analysis (ICA) transformation images and spatial texture features, analyzed the spectral reflectance and the suitable texture scale of each tree species. The tree species were classified according to different scale texture features, and compared tree species classification results of different features by support vector machine (SVM).
      ResultConcerning the object-oriented tree species classification combined with texture features, the overall accuracy of single-scale texture features was 87.11%, and the Kappa coefficient was 0.846. Combined with different scale texture features, the overall accuracy was 89.13%, and the Kappa coefficient was 0.87. Compared with the accuracy based on spectral features, the classification accuracy was improved by 4.03% and 6.05%, respectively. It showed that in object-oriented classification, the addition of texture features had a significant effect on improving the accuracy of tree species classification. The classification accuracy of tree species combined with different scale texture features was higher than single scale texture features, especially in the classification of other broadleaved tree species and Masson pine (Pinus massoniana), the producer accuracy was higher than single texture scale by 5.48% and 6.12%, respectively.
      ConclusionDifferent scale texture feature is more advantageous than single-scale texture feature, which improves the contribution of texture features in tree species classification. The spectrum of integrated airborne hyperspectral imagery and object-oriented classification of different scale texture features make the tree species identification more precise and accurate. It is effective for tree species classification in complex forest, and meets the application requirements in fine tree species identification based on airborne hyperspectral images.

       

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