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arXiv 2008.09837cs.CV
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再论时间动作定位的锚机制

Revisiting Anchor Mechanisms for Temporal Action Localization

School of Automation, Northwestern Polytechnical University(西北工业大学自动化学院);School of Mechano-Electronic Engineering, Xidian University(西安电子科技大学机电工程学院);Microsoft Research Asia(微软亚洲研究院)

Le Yang, Houwen Peng, Dingwen Zhang, Jianlong Fu, Junwei Han

摘要:

目前的大多数动作定位方法都遵循基于锚点的管道:通过预定义的锚点来描述动作实例,学习选择最接近地面实况的锚点,并通过细化来预测锚点的置信度。预定义的锚点对动作实例的位置和持续时间进行了预先设置,这有利于普通动作实例的本地化,但限制了处理具有剧烈变化的动作实例的灵活性,特别是对于极短或超长的动作实例。为了解决这个问题,本文提出了一种新的锚无动作定位模块,辅助动作定位的时间点。具体来说,该模块将动作实例表示为具有到起始边界和结束边界的距离的点,从而减轻了在动作定位和持续时间方面的预定义锚限制。所提出的无锚模块能够预测持续时间极短或超长的动作实例。通过将无锚模块与传统的基于锚的模块相结合,我们提出了一种新的动作定位框架,称为A2Net。无锚和基于锚的模块之间的合作实现了优于THUMOS 14上最先进的性能(45.5%对42.8%)。此外,综合实验表明,锚无和锚为基础的模块之间的互补性,使A2Net简单,但有效的。

英文摘要:

Most of the current action localization methods follow an anchor-based pipeline: depicting action instances by pre-defined anchors, learning to select the anchors closest to the ground truth, and predicting the confidence of anchors with refinements. Pre-defined anchors set prior about the location and duration for action instances, which facilitates the localization for common action instances but limits the flexibility for tackling action instances with drastic varieties, especially for extremely short or extremely long ones. To address this problem, this paper proposes a novel anchor-free action localization module that assists action localization by temporal points. Specifically, this module represents an action instance as a point with its distances to the starting boundary and ending boundary, alleviating the pre-defined anchor restrictions in terms of action localization and duration. The proposed anchor-free module is capable of predicting the action instances whose duration is either extremely short or extremely long. By combining the proposed anchor-free module with a conventional anchor-based module, we propose a novel action localization framework, called A2Net. The cooperation between anchor-free and anchor-based modules achieves superior performance to the state-of-the-art on THUMOS14 (45.5% vs. 42.8%). Furthermore, comprehensive experiments demonstrate the complementarity between the anchor-free and the anchor-based module, making A2Net simple but effective.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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