Data-driven action-value functions for evaluating players in professional team sports

As more and larger event stream datasets for professional sports become available, there is growing interest in modeling the complex play dynamics to evaluate player performance. Among these models, a common player evaluation method is assigning values to player actions. Traditional action-values metrics, however, consider very limited game context and player information. Furthermore, they provide directly related to goals (e.g., shots), not all actions. Recent work has shown that reinforcement learning provided powerful methods for addressing quantifying the value of player actions in sports. This dissertation develops deep reinforcement learning (DRL) methods for estimating action values in sports. We make several contributions to DRL for sports. First, we develop neural network architectures that learn an action-value Q-function from sports events logs to estimate each team\u27s expected success given the current match context. Specifically, our architecture models the game history with a recurrent network and predicts the probability that a team scores the next goal. From the learned Q-values, we derive a Goal Impact Metric (GIM) for evaluating a player\u27s performance over a game season. We show that the resulting player rankings are consistent with standard player metrics and temporally consistent within and across seasons. Second, we address the interpretability of the learned Q-values. While neural networks provided accurate estimates, the black-box structure prohibits understanding the influence of different game features on the action values. To interpret the Q-function and understand the influence of game features on action values, we design an interpretable mimic learning framework for the DRL. The framework is based on a Linear Model U-Tree (LMUT) as a transparent mimic model, which facilitates extracting the function rules and computing the feature importance for action values. Third, we incorporate information about specific players into the action values, by introducing a deep player representation framework. In this framework, each player is assigned a latent feature vector called an embedding, with the property that statistically similar players are mapped to nearby embeddings. To compute embeddings that summarize the statistical information about players, we implement a Variational Recurrent Ladder Agent Encoder (VaRLAE) to learn a contextualized representation for when and how players are likely to act. We learn and evaluate deep Q-functions from event data for both ice hockey and soccer. These are challenging continuous-flow games where game context and medium-term consequences are crucial for properly assessing the impact of a player\u27s actions

Semantic analysis of field sports video using a petri-net of audio-visual concepts

The most common approach to automatic summarisation and highlight detection in sports video is to train an automatic classifier to detect semantic highlights based on occurrences of low-level features such as action replays, excited commentators or changes in a scoreboard. We propose an alternative approach based on the detection of perception concepts (PCs) and the construction of Petri-Nets which can be used for both semantic description and event detection within sports videos. Low-level algorithms for the detection of perception concepts using visual, aural and motion characteristics are proposed, and a series of Petri-Nets composed of perception concepts is formally defined to describe video content. We call this a Perception Concept Network-Petri Net (PCN-PN) model. Using PCN-PNs, personalized high-level semantic descriptions of video highlights can be facilitated and queries on high-level semantics can be achieved. A particular strength of this framework is that we can easily build semantic detectors based on PCN-PNs to search within sports videos and locate interesting events. Experimental results based on recorded sports video data across three types of sports games (soccer, basketball and rugby), and each from multiple broadcasters, are used to illustrate the potential of this framework

Hockey Pose Estimation and Action Recognition using Convolutional Neural Networks to Ice Hockey

Human pose estimation and action recognition in ice hockey are one of the biggest challenges in computer vision-driven sports analytics, with a variety of difficulties such as bulky hockey wear, color similarity between ice rink and player jersey and the presence of additional sports equipment used by the players such as hockey sticks. As such, deep neural network architectures typically used for sports including baseball, soccer, and track and field perform poorly when applied to hockey. This research involves the design and implementation of deep neural networks for both pose estimation and action recognition can effectively evaluate the pose and the actions of a hockey player. First, a pre-trained convolutional neural network, known as the stacked hourglass network, is used to determine a hockey player's body placement in video frames, also known as pose estimation. The proposed method provides a tool to analyze the pose of a hockey player via broadcast video which aids in the eventual assessment of a hockey player's speed, shot accuracy, or other metrics. The algorithm demonstrated to be successful since it identifies on average 81.56% of the joints of a hockey player on a set of test images. Furthermore, inspired by the idea that modeling the pose of a hockey stick can improve hockey player pose estimation, a novel deep learning computer vision architecture known as the HyperStackNet has been designed and implemented for joint player and stick pose estimation. In addition to improving player pose estimation, the HyperStackNet architecture enables improved transfer learning from pre-trained stacked hourglass networks trained on a different domain. Experimental results demonstrate that when the HyperStackNet is trained to detect 18 different joint positions on a hockey player (including the hockey stick), the accuracy is 98.8% on the test dataset, thus demonstrating its efficacy for handling complex joint player and stick pose estimation from video. Extending from pose recognition, this research involves the development of an algorithm for accurate recognition of actions for hockey. To perform this action recognition, a convolutional neural network estimates actions through unifying latent pose and action recognition. The action recognition hourglass network, or ARHN, is designed to interpret player actions in ice hockey video using estimated pose. ARHN has three components. The first component is the latent pose estimator, the second transforms latent features to a common frame of reference, and the third performs action recognition. Since no benchmark dataset for pose estimation or action recognition is available for hockey players, we first had to generate such an annotated dataset. Experimental results show action recognition accuracy of 65% for four types of actions in hockey. When similar poses are merged to three and two classes, the accuracy rate increases to 71% and 78%, proving the potential of the methodology for automated action recognition in hockey

Algorithms for the Analysis of Spatio-Temporal Data from Team Sports

Modern object tracking systems are able to simultaneously record trajectories—sequences of time-stamped location points—for large numbers of objects with high frequency and accuracy. The availability of trajectory datasets has resulted in a consequent demand for algorithms and tools to extract information from these data. In this thesis, we present several contributions intended to do this, and in particular, to extract information from trajectories tracking football (soccer) players during matches. Football player trajectories have particular properties that both facilitate and present challenges for the algorithmic approaches to information extraction. The key property that we look to exploit is that the movement of the players reveals information about their objectives through cooperative and adversarial coordinated behaviour, and this, in turn, reveals the tactics and strategies employed to achieve the objectives. While the approaches presented here naturally deal with the application-specific properties of football player trajectories, they also apply to other domains where objects are tracked, for example behavioural ecology, traffic and urban planning

Proceedings of Mathsport international 2017 conference

Proceedings of MathSport International 2017 Conference, held in the Botanical Garden of the University of Padua, June 26-28, 2017. MathSport International organizes biennial conferences dedicated to all topics where mathematics and sport meet. Topics include: performance measures, optimization of sports performance, statistics and probability models, mathematical and physical models in sports, competitive strategies, statistics and probability match outcome models, optimal tournament design and scheduling, decision support systems, analysis of rules and adjudication, econometrics in sport, analysis of sporting technologies, financial valuation in sport, e-sports (gaming), betting and sports

Basketball game analyzing based on computer vision

As tremendous improvement in computer vision technology, various industries start to apply computer vision to analyze huge multimedia content. Sports as one of the biggest resource invested industries also step up to utilize this technology to enhance their sports intelligent products. The thesis is following this development to provide prototype implementations of computer vision algorithms in sports industry. Main objective is to develop initial algorithms to solve play-field detection and player tracking in basketball game video. Play-field detection is an important task in sports video content analysis, as it provides the foundation for further operations such as object detection, object tracking or semantic event highlight and summarization. On the other hand, player tracking highlight player movements in critical events in basketball game. It is also a challenging task to develop effective and efficient player tracking in basketball video, due to factors such as pose variation, illumination change, occlusion, and motion blur. This thesis proposed reliable and efficient prototype algorithms to address play- field detection and single player tracking. SURF algorithm is utilized and modified to offer precise location of play-field and overlay trajectory data to improve viewer’s experience on sports product. And compressive tracking algorithm implemented for the aim of capture and track single player in important events to reveal player’s secret tactics. Prototype implementation to meet the current needs in basketball video content analyzing field

Semantic Memory

How is it that we know what a dog and a tree are, or, for that matter, what knowledge is? Our semantic memory consists of knowledge about the world, including concepts, facts and beliefs. This knowledge is essential for recognizing entities and objects, and for making inferences and predictions about the world. In essence, our semantic knowledge determines how we understand and interact with the world around us. In this chapter, we examine semantic memory from cognitive, sensorimotor, cognitive neuroscientific, and computational perspectives. We consider the cognitive and neural processes (and biases) that allow people to learn and represent concepts, and discuss how and where in the brain sensory and motor information may be integrated to allow for the perception of a coherent “concept”. We suggest that our understanding of semantic memory can be enriched by considering how semantic knowledge develops across the lifespan within individuals