A Multistage Information Complementary Fusion Network Based on Flexible-Mixup for HSI-X Image Classification.

Mixup-based data augmentation has been proven to be beneficial to the regularization of models during training, especially in the remote-sensing field where the training data is scarce. However, in the process of data augmentation, the Mixup-based methods ignore the target proportion in different inputs and keep the linear insertion ratio consistent, which leads to the response of label space even if no effective objects are introduced in the mixed image due to the randomness of the augmentation process. Moreover, although some previous works have attempted to utilize different multimodal interaction strategies, they could not be well extended to various remote-sensing data combinations. To this end, a multistage information complementary fusion network based on flexible-mixup (Flex-MCFNet) is proposed for hyperspectral-X image classification. First, to bridge the gap between the mixed image and the label, a flexible-mixup (FlexMix) data augmentation strategy is designed, where the weight of the label increases with the ratio of the input image to prevent the negative impact on the label space because of the introduction of invalid information. More importantly, to summarize diverse remote-sensing data inputs including various modal supplements and uncertainties, a multistage information complementary fusion network (MCFNet) is developed. After extracting the features of hyperspectral and complementary modalities [X-modal, including multispectral, synthetic aperture radar (SAR), and light detection and ranging (LiDAR)] separately, the information between complementary modalities is fully interacted and enhanced through multiple stages of information complement and fusion, which is used for the final image classification. Extensive experimental results have demonstrated that Flex-MCFNet can not only effectively expand the training data, but also adequately regularize different data combinations to achieve state-of-the-art performance.