作者:Xue Yang, Jirui Yang, Junchi Yan, Yue Zhang, Tengfei Zhang, Zhi Guo, Sun Xian, Kun fu
机构:
论文全称:Dynamic Anchor Learning for Arbitrary-Oriented Object Detection
**发布时间:**2020
发布期刊:arxiv
论文地址:https://arxiv.org/pdf/2012.04150v2.pdf
代码:
https://github.com/ming71/UCAS-AOD-benchmark
创新:
Arbitrary-oriented objects widely appear in natural scenes, aerial photographs, remote sensing images, etc., and thus arbitrary-oriented object detection has received considerable attention. Many current rotation detectors use plenty of anchors with different orientations to achieve spatial alignment with ground truth boxes. Intersection-over-Union (IoU) is then applied to sample the positive and negative candidates for training. However, we observe that the selected positive anchors cannot always ensure accurate detections after regression, while some negative samples can achieve accurate localization. It indicates that the quality assessment of anchors through IoU is not appropriate, and this further leads to inconsistency between classification confidence and localization accuracy. In this paper, we propose a dynamic anchor learning (DAL) method, which utilizes the newly defined matching degree to comprehensively evaluate the localization potential of the anchors and carries out a more efficient label assignment process. In this way, the detector can dynamically select high-quality anchors to achieve accurate object detection, and the divergence between classification and regression will be alleviated. With the newly introduced DAL, we can achieve superior detection performance for arbitrary-oriented objects with only a few horizontal preset anchors. Experimental results on three remote sensing datasets HRSC2016, DOTA, UCAS-AOD as well as a scene text dataset ICDAR 2015 show that our method achieves substantial improvement compared with the baseline model. Besides, our approach is also universal for object detection using horizontal bound box. The code and models are available at https://github.com/ming71/DAL.
目前,基于anchor的算法在训练时首先根据将预设的anchor和目标根据IoU大小进行空间匹配,以一定的阈值(如0.5)选出合适数目的anchor作为正样本用于回归分配的物体。但是这会导致两个问题:
为了进一步验证上述第二点现象是否具有普遍性,统计了训练过程的所有样本IoU分布图,以及分类回归分数散点图
综上所述,定位性能并不完全依赖于anchor和GT之间的空间对齐(一般用两者之间的IoU来衡量)