Adaptive Dense Pseudo Label Selection for Semi-supervised Oriented Object Detection

Recently, dense pseudo-label, which directly selects pseudo labels from the original output of the teacher model without any complicated post-processing steps, has received considerable attention in semi-supervised object detection (SSOD). However, for the multi-oriented and dense objects that are common in aerial scenes, existing dense pseudo-label selection methods are inefficient and impede the performance in semi-supervised oriented object detection. Therefore, we propose Adaptive Dense Pseudo Label Selection (ADPLS) for semi-supervised oriented object detection. In ADPLS, we design a simple but effective adaptive mechanism to guide the selection of dense pseudo labels. Specifically, we propose the mean Feature-Richness Score (mFRS) to estimate the density of potential objects and use this score to adjust the number of dense pseudo labels. On the DOTA-v1.5 benchmark, the proposed method outperforms previous methods especially when labeled data are scarce. For example, it achieves 49.78 mAP given only 5% of annotated data, which surpasses previous state-of-the-art method given 10% of annotated data by 1.15 mAP. Our codes will be available soon.