Spatio-temporal relations among facial action units (AUs) convey significant
information for AU detection yet have not been thoroughly exploited. The main
reasons are the limited capability of current AU detection works in
simultaneously learning spatial and temporal relations, and the lack of precise
localization information for AU feature learning. To tackle these limitations,
we propose a novel spatio-temporal relation and attention learning framework
for AU detection. Specifically, we introduce a spatio-temporal graph
convolutional network to capture both spatial and temporal relations from
dynamic AUs, in which the AU relations are formulated as a spatio-temporal
graph with adaptively learned instead of predefined edge weights. Moreover, the
learning of spatio-temporal relations among AUs requires individual AU
features. Considering the dynamism and shape irregularity of AUs, we propose an
attention regularization method to adaptively learn regional attentions that
capture highly relevant regions and suppress irrelevant regions so as to
extract a complete feature for each AU. Extensive experiments show that our
approach achieves substantial improvements over the state-of-the-art AU
detection methods on BP4D and especially DISFA benchmarks.

本研究提出了一种基于空间 - 时间关系和注意力机制的面部动作单元检测框架，其中使用了空间 - 时间图卷积网络来捕捉动态面部动作单元的空间和时间关系，并使用自适应学习的边界权重来形成关系图。此外，为了学习 AU 之间的时空关系，我们提出了一种注意力机制，以自适应地学习区域注意力，并通过抑制不相关区域来提取每个 AU 的完整特征。实验结果显示，我们的方法在 BP4D 和 DISFA 基准测试中实现了显著的改进。