Incremental Detection of Remote Sensing Objects with Feature Pyramid and Knowledge Distillation

When a detection model that has been well-trained on a set of classes faces new classes, incremental learning is always necessary to adapt the model to detect the new classes. In most scenarios, it is required to preserve the learned knowledge of the old classes during incremental learning rather than reusing the training data from the old classes. Since the objects in remote sensing images often appear in various sizes, arbitrary directions, and dense distribution, it further makes incremental learning-based object detection more difficult. In this article, a new architecture for incremental object detection is proposed based on feature pyramid and knowledge distillation. Especially, by means of a feature pyramid network (FPN), the objects with various scales are detected in the different layers of the feature pyramid. Motivated by Learning without Forgetting (LwF), a new branch is expended in the last layer of FPN, and knowledge distillation is applied to the outputs of the old branch to maintain the old learning capability for the old classes. Multitask learning is adopted to jointly optimize the losses from two branches. Experiments on two widely used remote sensing data sets show our promising performance compared with state-of-the-art incremental object detection methods.