With the development of optical imaging technology, when a hyperspectral camera continuously obtains hyperspectral imageries in a short period of time, temporal information will also become available. Because the spatial-spectral information and historical trajectory play different roles in moving target detection, fusion of different information has become a good framework for moving target detection. However, it is difficult to choose a suitable scale to represent different types of moving targets which have different scales and different moving speeds. To solve this problem, multiscale spatial-spectral detection and multi-scale temporal variance filter is proposed. Experimental results demonstrated that adopting multi-scale fusion strategies in spatial-spectral map and historical trajectory map (MSSH) in real hyperspectral moving target datasets can effectively improve the detection performance of different moving targets.
Convolution neural network (CNN) has been know as a state-of-the-art technique for hyperspectral image (HSI) classification. However, the basic CNN architecture still has obstacles to deal with the intraclass diversity caused by spatial variability of spectral signature, especially in the case of highly limited training samples. Furthermore, they also have challenges to exploit the relationships between different features of the same object. In this paper, we propose a new network architecture based on matrix capsule network (MatCapNet) to alleviate these problems. To extract spectral-spatial features, the proposed network takes the 3-D neighboring blocks as input data. Specifically, the network consists of two conventional convolution layers, a primary matrix capsule layer, and a convolution matrix capsule layer. The proposed network uses spread loss to maximize the gap of activation values between the target class and other wrong classes. To learn more relevant instantiation parameters of the input data, a decoder network is used to reconstruct the input center spectral signature. Finally, the reconstruction loss and the spread loss are added at a certain ratio to optimize network parameters. Besides, in order to solve the problem of unbalanced sample sizes, the sample weight coefficient is utilized. The proposed approaches are carried out on two well-known HSI data sets. Compared with other state-of-the-art methods, the experiment results exhibit that the proposed network could provide a competitive advantage in terms of classification accuracy.
In this paper, we propose a constrained sparse representation (CSR) based algorithm for target detection in hyperspectral imagery. This algorithm is based on the concept that each pixel lies in a low-dimensional sub- space spanned by target and background training samples. Therefore, it can be linearly represented by these samples weighted by a sparse vector. According to the spectral linear mixture model (LMM), the non-negativity constraint and sum-to-one constraint are imposed to the sparse vector. According to the Karush Kuhn Tucker (KKT) conditions, the upper bound constraint on sparsity level is removed. Besides, to alleviate the effects of target contamination in the background dictionary, an upper bound constraint is given to the weights corresponding to the atoms in the background dictionary. Finally, this constrained sparsity model is solved by a fast sequential minimal optimization (SMO) method. Different from other sparsity-based models, both the residuals and weights are used to detect targets in our algorithm, resulting in a better detection performance. The major advantage of the proposed method is the capability to suppress target signals in the background dictionary. The proposed method was compared to several traditional detectors including spectral matched filter (SMF), adaptive subspace detector (ASD), matched subspace detector (MSD), and sparse representation (SR) based detector. The commonly used receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) are adopted for performance evaluation. Extensive experiments are conducted on two real hyperspectral data sets. It is demonstrated that our CSR method is robust to different target contamination levels in the background dictionary. From these experiments, it can be seen that our CSR method achieves a much higher target detection probability than other traditional methods at all false alarm rates. Meanwhile, our CSR method achieves the highest AUC value, which is significantly larger than most traditional methods. Moreover, the proposed method also have a relatively low computational cost.
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