Adaptive Spatial Pyramid Constraint for Hyperspectral Image Classification with Limited Training Samples

Deep learning-based methods have made significant progress in hyperspectral image (HSI) classification in recent years. However, deep learning-based methods usually rely on a large number of samples, and in many cases, it is difficult to label HSI and only limited training samples are available. To solve this problem, an HSI classification method based on adaptive spatial pyramid constraint (ASPC) is proposed to make full use of the global spatial neighborhood information of the labeled samples, which can improve the generalization ability of the classification model. The main steps of the proposed method are as follows. First, an HSI complexity evaluation method based on edge detection is proposed to assess the homogeneity of the objects in the HSI. Second, an HSI pyramid segmentation method based on spatial pyramid is proposed to generate multiscale subregions, where HSI complexity is used to adaptively determine the scale of the segmentation. Third, a spatial supervised constraint is proposed to generate the loss function of labeled subregions. Fourth, a spatial unsupervised constraint is proposed to generate the loss function of unlabeled subregions. The proposed method fully explores the spatial-spectral correlation between unlabeled samples and labeled samples, and add corresponding constraints to the training objective according to the correlation. By adding the ASPC, the trained model becomes more robust and can make full use of the limited training samples. To verify the effectiveness of the proposed method, three benchmark hyperspectral datasets are used to verify the performance of the proposed method. Experimental results show that the performance of this method is better than the existing state-of-the-art methods.