text: Abstract In this paper, we propose a novel approach for exploiting structural relations to track multiple objects that may undergo long-term occlusion and abrupt motion. We use a model-free approach that relies only on annotations given in the first frame of the video to track all the objects online, i.e. without knowledge from future frames. We initialize a probabilistic Attributed Relational Graph (ARG) from the first frame, which is incrementally updated along the video. Instead of using the structural information only to evaluate the scene, the proposed approach considers it to generate new tracking hypotheses. In this way, our method is capable of generating relevant object candidates that are used to improve or recover the track of lost objects. The proposed method is evaluated on several videos of table tennis, volleyball, and on the ACASVA dataset. The results show that our approach is very robust, flexible and able to outperform other state-of-the-art methods in sports videos that present structural patterns.
  @cite_28: Multiple object tracking (MOT) is a very challenging task yet of fundamental importance for many practical applications. In this paper, we focus on the problem of tracking multiple players in sports video which is even more difficult due to the abrupt movements of players and their complex interactions. To handle the difficulties in this problem, we present a new MOT algorithm which contributes both in the observation modeling level and in the tracking strategy level. For the observation modeling, we develop a progressive observation modeling process that is able to provide strong tracking observations and greatly facilitate the tracking task. For the tracking strategy, we propose a dual-mode two-way Bayesian inference approach which dynamically switches between an offline general model and an online dedicated model to deal with single isolated object tracking and multiple occluded object tracking integrally by forward filtering and backward smoothing. Extensive experiments on different kinds of sports videos, including football, basketball, as well as hockey, demonstrate the effectiveness and efficiency of the proposed method.
  @cite_9: In this paper we present an efficient algorithm for tracking multiple players during indoor sports matches. A sports match can be considered as a semi-controlled environment for which a set of closed-world assumptions regarding the visual as well as the dynamical properties of the players and the court can be derived. These assumptions are then used in the context of particle filtering to arrive at a computationally fast, closed-world, multi-player tracker. The proposed tracker is based on multiple, single-player trackers, which are combined using a closed-world assumption about the interactions among players. With regard to the visual properties, the robustness of the tracker is achieved by deriving a novel sports-domain-specific likelihood function and employing a novel background-elimination scheme. The restrictions on the player's dynamics are enforced by employing a novel form of local smoothing. This smoothing renders the tracking more robust and reduces the computational complexity of the tracker. We evaluated the proposed closed-world, multi-player tracker on a challenging data set. In comparison with several similar trackers that did not utilize all of the closed-world assumptions, the proposed tracker produced better estimates of position and prediction as well as reducing the number of failures.
  @cite_29: In this work, we consider the problem of background pixels information recovering which can be used, for example, in applications concerning segmentation and tracking of components in video images. Shortly, to recover the background of image sequences representing outdoor scenes, we consider a non-parametric morphological leveling operation, which takes into account the specific problem of lighting changes and the fact that we can have both slow and fast motion in the scene. We illustrate the segmentation of players based on the difference between image sequences and the corresponding recovered background representation. We also discuss the reduction of shadows in digital video of soccer games and show the good results of the whole background recovering and segmentation process.
  @cite_12: There is a growing scientific interest in the study of tactical and physical attributes in futsal. These analyses use the players' motion, generally obtained with visual tracking, a task still not fully automated and that requires laborious guidance. In this regard, this work introduces an automatic procedure for estimating the positions of futsal players as probability distributions using multiple cameras and particle filters, reducing the need for human intervention during the process. In our framework, each player position is defined as a non-parametric distribution, which we track with the aid of particle filters. At every frame, we create the observation model by combining information from multiple cameras: a multimodal probability distribution function in court plane describing the likely players' positions. In order to decrease human intervention, we address the confusion between players during tracking using an appearance model to change and update the observation function. The experiments carried out reveal tracking errors below 70cm and enforce the method's potential for aiding sports teams in different technical aspects.
  @cite_11: The problem of tracking a varying number of non-rigid objects has two major difficulties. First, the observation models and target distributions can be highly non-linear and non-Gaussian. Second, the presence of a large, varying number of objects creates complex interactions with overlap and ambiguities. To surmount these difficulties, we introduce a vision system that is capable of learning, detecting and tracking the objects of interest. The system is demonstrated in the context of tracking hockey players using video sequences. Our approach combines the strengths of two successful algorithms: mixture particle filters and Adaboost. The mixture particle filter [17] is ideally suited to multi-target tracking as it assigns a mixture component to each player. The crucial design issues in mixture particle filters are the choice of the proposal distribution and the treatment of objects leaving and entering the scene. Here, we construct the proposal distribution using a mixture model that incorporates information from the dynamic models of each player and the detection hypotheses generated by Adaboost. The learned Adaboost proposal distribution allows us to quickly detect players entering the scene, while the filtering process enables us to keep track of the individual players. The result of interleaving Adaboost with mixture particle filters is a simple, yet powerful and fully automatic multiple object tracking system.
summary: Visual tracking in sports has been receiving great attention over the years and it has been tackled in many different ways. Due to its simplicity and robustness to deal with more complex models, methods based on particle filters became popular @cite_9 @cite_11 @cite_28 . Another significant approach relies on the fact that often the background is static and, therefore, tracking may be performed by using background subtraction methods @cite_29 . Other authors explore the use of multiple cameras to obtain more reliable results @cite_12 .