In group activity recognition, the temporal dynamics of the whole activity
can be inferred based on the dynamics of the individual people representing the
activity. We build a deep model to capture these dynamics based on LSTM
(long-short term memory) models. To make use of these ob- servations, we
present a 2-stage deep temporal model for the group activity recognition
problem. In our model, a LSTM model is designed to represent action dynamics of
in- dividual people in a sequence and another LSTM model is designed to
aggregate human-level information for whole activity understanding. We evaluate
our model over two datasets: the collective activity dataset and a new volley-
ball dataset. Experimental results demonstrate that our proposed model improves
group activity recognition perfor- mance with compared to baseline methods.

通过 LSTM 模型构建 2 阶段深层次模型，从而更好地理解群体活动，利用这些动态实现群体活动识别，实验结果表明，该模型可以有效提高群体活动识别性能。

分层深层时间模型用于团体活动识别

A Hierarchical Deep Temporal Model for Group Activity Recognition

Rich semantic relations are important in a variety of visual recognition
problems. As a concrete example, group activity recognition involves the
interactions and relative spatial relations of a set of people in a scene.
State of the art recognition methods center on deep learning approaches for
training highly effective, complex classifiers for interpreting images.
However, bridging the relatively low-level concepts output by these methods to
interpret higher-level compositional scenes remains a challenge. Graphical
models are a standard tool for this task. In this paper, we propose a method to
integrate graphical models and deep neural networks into a joint framework.
Instead of using a traditional inference method, we use a sequential inference
modeled by a recurrent neural network. Beyond this, the appropriate structure
for inference can be learned by imposing gates on edges between nodes.
Empirical results on group activity recognition demonstrate the potential of
this model to handle highly structured learning tasks.

本文提出了一种将图形模型和深度神经网络集成到一个联合框架中的方法，在序列推断方面采用递归神经网络的建模，通过对节点之间的边缘施加门来学习推断的适当结构。实证研究表明，这种模型具有处理高度结构化学习任务的潜力，再现了在群体活动识别问题的表现。

结构推理机：循环神经网络用于分析群体活动识别中的关系

Structure Inference Machines: Recurrent Neural Networks for Analyzing  Relations in Group Activity Recognition

This paper presents a deep neural-network-based hierarchical graphical model
for individual and group activity recognition in surveillance scenes. Deep
networks are used to recognize the actions of individual people in a scene.
Next, a neural-network-based hierarchical graphical model refines the predicted
labels for each class by considering dependencies between the classes. This
refinement step mimics a message-passing step similar to inference in a
probabilistic graphical model. We show that this approach can be effective in
group activity recognition, with the deep graphical model improving recognition
rates over baseline methods.

本文提出了一种基于深度神经网络和分层图模型的个人和群体活动监测方案，使用深度网络识别场景中个人的动作，并通过考虑类别间的依赖关系使用神经网络分层图模型完善每个类别的预测标签，该方法能有效改善基准测试方法的识别率。