Marine oil spills are one of the most serious problems of marine environmental pollution. Hyperspectral remote sensing has been proven to be an effective tool for monitoring marine oil spills. To make full use of spectral and spatial features, this study proposes a spectral-spatial features integrated network (SSFIN) and applies it for hyperspectral detection of a marine oil spill. Specifically, 1-D and 2-D convolutional neural network (CNN) models have been employed for the extraction of the spectral and spatial features, respectively. During the stage of spatial feature extraction, three consecutive convolution layers are concatenated to achieve the fusion of multilevel spatial features. Next, the extracted spectral and spatial features are concatenated and fed to the fully connected layer so as to obtain the joint spectral-spatial features. In addition, L2 regularization is applied to the convolution layer to prevent overfitting, and dropout operation is employed to the full connection layer to improve the network performance. The effectiveness of the method proposed here has firstly been verified on the Pavia University dataset with competitive classification experimental results. Eventually, the experimental results upon oil spill datasets demonstrate the strong capacity of oil spill detection by this method, which can effectively distinguish thick oil film, thin oil film, and seawater.

Hyperspectral image (HSI) classification has always drawn great attention in the field of remote sensing. Various deep learning models are in the ascendant and gradually applied to HSI classification. Nevertheless, limited-labeled and class-imbalanced datasets largely make the classifier prone to overfitting. To address the above problem, this article proposes a two-branch generative adversarial network with multiscale connections (TBGAN), which includes two generators to produce the spectral and spatial samples, respectively. Thereinto, the spectral generator is imbued with the self-attention mechanism to maximumly capture the long-term dependencies across the spectral bands. And meanwhile, an elaborated discriminator with two branches is devised in TBGAN for extracting the joint spectral-spatial features. Besides, the multiscale connections are placed between the discriminator and two generators to alleviate the instability problems caused by the inherently backward propagation of gradients in GAN. Furthermore, a feature-matching term is added to the loss function to prevent the generators from overtraining upon the current discriminator, thereby further improving the stability of the network. Experiments upon three benchmark datasets demonstrate that TBGAN achieves an extremely competitive classification accuracy and exerts lower sensitivity to the training sample size compared with several state-of-the-art methods.

Deep learning methods have been proved outperforming the traditional methods in the field of hyperspectral image classification (HSIC). However, in pursuit of higher accuracy, HSIC networks have become deeper and more complex, resulting in excessive parameters and computational cost. To deploy neural networks on small platforms such as mobile or embedded devices, many studies have focused on lightweight HSIC networks. Currently, these researches are dominated by patch-based networks, which suffer from the low accuracy caused by lightweight scale and slow inference speed derived from structural deficiencies of such networks. It is worth noting that full convolutional networks are able to achieve fast inference, but they tend to consume massive memory. To this end, this paper proposes a novel lightweight HSIC method, which consists of a successive spatial rectified network (SSRNet) and a non-central positional sampling (NCPS) strategy. SSRNet is composed of a local channel attention based spectral full convolutional network and several separable atrous spatial pyramid modules. These shallow sub-networks are concatenated together to progressively optimize their outputs by successive spatial rectified learning. For decreasing memory access cost, SSRNet makes little patches as input to perform patch-wise pixels-to-pixels learning. After training, SSRNet is able to adapt to any size of hyperspectral images and complete fast inference of the full image directly. In particular, the NCPS sampling strategy enables all labeled pixels to equally traverse all spatial positions of each training patch through the positional shift sampling, which effectively alleviates the sparse problem of hyperspectral semantic labels. Experiments upon three public benchmark datasets indicate that SSRNet is comparable to the state-of-the-art methods in classification accuracy with less than 0.15M parameters and only occupy less than 10MB memory for single forward computation. Moreover, SSRNet behaves significantly superior to the traditional patch-based networks in term of the inference speed. The source codes can be available from the website of https://github.com/Pancakerr/HSIC-platform.