The Instantaneous Accuracy: a Novel Metric for the Problem of Online Human Behaviour Recognition in Untrimmed Videos

Rethinking Online Action Detection in Untrimmed Videos: A Novel Online Evaluation Protocol

The Online Action Detection (OAD) problem needs to be revisited. Unlike traditional offline action detection approaches, where the evaluation metrics are clear and well established, in the OAD setting we find very few works and no consensus on the evaluation protocols to be used. In this work we propose to rethink the OAD scenario, clearly defining the problem itself and the main characteristics that the models which are considered online must comply with. We also introduce a novel metric: the Instantaneous Accuracy ($IA$). This new metric exhibits an \emph{online} nature and solves most of th…

ActionSwitch：流式视频中同时动作的类无关检测

ActionSwitch: Class-agnostic Detection of Simultaneous Actions in Streaming Videos

本文提出ActionSwitch，首个类无关的在线时间动作定位框架，通过消除类别依赖和引入保守性损失，在Epic-Kitchens 100和FineAction上实现最先进的重叠动作检测性能。

Characterizing Human Behaviours Using Statistical Motion Descriptor

Identifying human behaviors is a challenging research problem due to the complexity and variation of appearances and postures, the variation of camera settings, and view angles. In this paper, we try to address the problem of human behavior identification by introducing a novel motion descriptor based on statistical features. The method first divide the video into N number of temporal segments. Then for each segment, we compute dense optical flow, which provides instantaneous velocity information for all the pixels. We then compute Histogram of Optical Flow (HOOF) weighted by the norm and quan…

SMC-NCA：语义引导的多级对比用于半监督时间动作分割

SMC-NCA: Semantic-guided Multi-level Contrast for Semi-supervised Temporal Action Segmentation

本文提出SMC-NCA方法，利用语义引导的多级对比和邻域一致性感知单元，为半监督时间动作分割提取强帧级表示，在多个基准上显著提升性能。

动作-动态建模与跨时间交互用于在线动作理解

Action-Dynamics Modeling and Cross-Temporal Interaction for Online Action Understanding

本文提出状态特定模型（SSM）用于统一动作检测与预见，通过关键状态压缩、动作模式学习和跨时间交互模块，提升动作理解性能。