Recent methods for video action recognition have reached outstanding performances on existing benchmarks. However, they tend to leverage context such as scenes or objects instead of focusing on understanding the human action itself. For instance, a tennis field leads to the prediction playing tennis irrespectively of the actions performed in the video. In contrast, humans have a more complete understanding of actions and can recognize them without context. The best example of out-of-context actions are mimes, that people can typically recognize despite missing relevant objects and scenes. In this paper, we propose to benchmark action recognition methods in the absence of context. We therefore introduce a novel dataset, Mimetics, consisting of mimed actions for a subset of 50 classes from the Kinetics benchmark. Our experiments show that state-of-the-art 3D convolutional neural networks obtain disappointing results on such videos, highlighting the lack of true understanding of the human actions. Body language, captured by human pose and motion, is a meaningful cue to recognize out-of-context actions. We thus evaluate several pose-based baselines, either based on explicit 2D or 3D pose estimates, or on transferring pose features to the action recognition problem. This last method, less prone to inherent pose estimation noise, performs better than the other pose-based baselines, suggesting that an explicit pose representation might not be optimal for real-world action recognition.

该论文提出了一个新的数据集 Mimetics, 利用浅层神经网络在解决视频动作识别中缺乏对人类动作真正理解的问题上表现出惊人的效果，强调了人体语言通过人体姿态向行为识别问题转移的趋势。

模仿学习：探索解读人类超出环境限制的行为