Unsupervised Recognition of Unknown Objects for Open-World Object Detection.

Open-world object detection (OWOD) extends object detection problem to a realistic and dynamic scenario, where a detection model is required to be capable of detecting both known and unknown objects and incrementally learning newly introduced knowledge. Current OWOD models detect the unknowns that exhibit similar features to the known objects, but they suffer from a severe label bias problem, i.e., they tend to detect all regions (including unknown object regions) that are dissimilar to the known objects as part of the background. To eliminate the label bias, this article proposes a novel module, namely reconstruction error-based Weibull (REW) model, that learns an unsupervised discriminative model for recognizing true unknown objects based on prior knowledge of object occurrence frequency via Weibull modeling. The resulting model can be further refined by another module of our method, called REW-enhanced object localization network (ROLNet), which iteratively extends pseudo-unknown objects to the unlabeled regions. Experimental results show that our method 1) significantly outperforms the prior SOTA in detecting unknown objects while maintaining competitive performance of detecting known object classes on the MS COCO dataset and 2) achieves better generalization ability on the LVIS and Objects365 datasets. Code is available at https://github.com/frh23333/mepu-owod.