DIE-CDK: A Discriminative Information Enhancement Method With Cross-Modal Domain Knowledge for Fine-Grained Ship Detection

Due to the overarching similarities of ships, subtle information is imperative for fine-grained ship detection. However, this information is easily lost in adverse weather (e.g., fog, rain, snow, and cloud) or occlusion scenarios. Experts can quickly and accurately recognize fine-grained objects because they have the domain knowledge to help them find the most discriminative information (e.g., edge, structure, texture, and class semantics); thus, they do not need a lot of information to make an identification. Motivated by it, we propose a discriminative information enhancement method with cross-modal domain knowledge (DIE-CDK) for fine-grained ship detection. The core idea behind DIE-CDK is to enhance the discriminative information about fine-grained ships by fusing cross-modal domain knowledge. The introduced cross-modal domain knowledge comprises local and global knowledge: 1) local knowledge is the knowledge of visual shape (e.g., edge contour) which is extracted from the image domain; and 2) global knowledge is the knowledge of the class semantics which is obtained from the common sense domain. In addition, to further study fine-grained ship detection, we introduce a Fine-grained ship dataset (called FgShips). Experiments show that our proposed DIE-CDK method achieves impressive gains in detection performance and outperforms state-of-the-art methods on fine-grained ship and public datasets.