There is a large variety of trackers, which have been proposed in the literature during the last two decades with some mixed success. Object tracking in realistic scenarios is a difficult problem, therefore, it remains a most active area of research in computer vision. A good tracker should perform well in a large number of videos involving illumination changes, occlusion, clutter, camera motion, low contrast, specularities, and at least six more aspects. However, the performance of proposed trackers have been evaluated typically on less than ten videos, or on the special purpose datasets. In this paper, we aim to evaluate trackers systematically and experimentally on 315 video fragments covering above aspects. We selected a set of nineteen trackers to include a wide variety of algorithms often cited in literature, supplemented with trackers appearing in 2010 and 2011 for which the code was publicly available. We demonstrate that trackers can be evaluated objectively by survival curves, Kaplan Meier statistics, and Grubs testing. We find that in the evaluation practice the F-score is as effective as the object tracking accuracy (OTA) score. The analysis under a large variety of circumstances provides objective insight into the strengths and weaknesses of trackers.

/pdf/visual-tracking-an-experimental-survey-50w2t40998.pdf

Visual Tracking: An Experimental Survey

Recent technological developments have led to the production of inexpensive, non-invasive, miniature magneto-inertial sensors, ideal for obtaining sport performance measures during training or competition. This systematic review evaluates current evidence and the future potential of their use in sport performance evaluation. Articles published in English (April 2017) were searched in Web-of-Science, Scopus, Pubmed, and Sport-Discus databases. A keyword search of titles, abstracts and keywords which included studies using accelerometers, gyroscopes and/or magnetometers to analyse sport motor-tasks performed by athletes (excluding risk of injury, physical activity, and energy expenditure) resulted in 2040 papers. Papers and reference list screening led to the selection of 286 studies and 23 reviews. Information on sport, motor-tasks, participants, device characteristics, sensor position and fixing, experimental setting and performance indicators was extracted. The selected papers dealt with motor capacity assessment (51 papers), technique analysis (163), activity classification (19), and physical demands assessment (61). Focus was placed mainly on elite and sub-elite athletes (59%) performing their sport in-field during training (62%) and competition (7%). Measuring movement outdoors created opportunities in winter sports (8%), water sports (16%), team sports (25%), and other outdoor activities (27%). Indications on the reliability of sensor-based performance indicators are provided, together with critical considerations and future trends.

Trends Supporting the In-Field Use of Wearable Inertial Sensors for Sport Performance Evaluation: A Systematic Review

Until recently tactical analysis in elite soccer were based on observational data using variables which discard most contextual information. Analyses of team tactics require however detailed data from various sources including technical skill, individual physiological performance, and team formations among others to represent the complex processes underlying team tactical behavior. Accordingly, little is known about how these different factors influence team tactical behavior in elite soccer. In parts, this has also been due to the lack of available data. Increasingly however, detailed game logs obtained through next-generation tracking technologies in addition to physiological training data collected through novel miniature sensor technologies have become available for research. This leads however to the opposite problem where the shear amount of data becomes an obstacle in itself as methodological guidelines as well as theoretical modelling of tactical decision making in team sports is lacking. The present paper discusses how big data and modern machine learning technologies may help to address these issues and aid in developing a theoretical model for tactical decision making in team sports. As experience from medical applications show, significant organizational obstacles regarding data governance and access to technologies must be overcome first. The present work discusses these issues with respect to tactical analyses in elite soccer and propose a technological stack which aims to introduce big data technologies into elite soccer research. The proposed approach could also serve as a guideline for other sports science domains as increasing data size is becoming a wide-spread phenomenon.

/pdf/big-data-and-tactical-analysis-in-elite-soccer-future-2pu4o8bjc4.pdf

Big data and tactical analysis in elite soccer: future challenges and opportunities for sports science

Tactical match performance depends on the quality of actions of individual players or teams in space and time during match-play in order to be successful. Technological innovations have led to new possibilities to capture accurate spatio-temporal information of all players and unravel the dynamics and complexity of soccer matches. The main aim of this article is to give an overview of the current state of development of the analysis of position data in soccer. Based on the same single set of position data of a high-level 11 versus 11 match (Bayern Munich against FC Barcelona) three different promising approaches from the perspective of dynamic systems and neural networks will be presented: Tactical performance analysis revealed inter-player coordination, inter-team and inter-line coordination before critical events, as well as team-team interaction and compactness coefficients. This could lead to a multi-disciplinary discussion on match analyses in sport science and new avenues for theoretical and practical implications in soccer.

Current Approaches to Tactical Performance Analyses in Soccer Using Position Data

There is a need for a collective variable that captures the dynamics of team sports like soccer at match level. The centroid positions and surface areas of two soccer teams potentially describe the coordinated flow of attacking and defending in small-sided soccer games at team level. The aim of the present study was to identify an overall game pattern by establishing whether the proposed variables were linearly related between teams over the course of the game. In addition, we tried to identify patterns in the build-up of goals. A positive linear relation and a negative linear relation were hypothesized for the centroid positions and surface areas respectively. Finally, we hypothesized that deviations from these patterns are present in the build-up of goals. Ten young male elite soccer players (mean age 17.3, s=0.7) played three small-sided soccer games (4-a-side) of 8 minutes as part of their regular training routine. An innovative player tracking system, local position measurement (LPM), was us...

Oscillations of centroid position and surface area of soccer teams in small-sided games

Implementation of Recurrence Analysis algorithms in a dashboard for practical application in Football

<h3>Introduction</h3> Alcohol is the leading cause of cirrhosis in western populations. Early identification of high-risk drinkers followed by intervention is an effective way to reduce harm. We aim to assess the feasibility of integrating transient elastography (TE) into community alcohol services and to determine its impact on modifying drinking behaviours. <h3>Method</h3> A prospective cohort study was conducted at a community alcohol clinic in Nottingham (April-2012 to March-2014). Patients (&gt;18years) with a primary alcohol problem were recruited. Those known to liver services or to have chronic liver disease were excluded. Significant liver fibrosis was defined by a liver stiffness measure (LSM) of &gt;8 kilopascals (kPa). Follow-up was for a minimum of six months. Data were descriptively analysed for significant differences between patients with a normal LSM versus raised LSM. <h3>Results</h3> 156 patients were invited; n=87 attended and n=86 underwent successful TE. The majority were male (n=53, 70.0%) and the mean age was 46.3 years (SD +/-9.8). Median liver stiffness was 6.9kPa. Clinically significant liver fibrosis was identified in n=33 (38.4%), of which n=6 were in cirrhotic range (≥15 kPa). Baseline median self-reported alcohol intake for normal stiffness was 126 units per week and in raised stiffness was 149.0 units per week the difference was non-significant (p=0.338). Median reduction in self-report alcohol intake in whole cohort was 65.0 units per week (p=&lt;0.001), in normal liver stiffness group was 25.0 units per week (p=0.154), and in raised liver stiffness group was 78.5 units per week (p&lt;0.001). <h3>Conclusion</h3> The study demonstrated that transient elastography is a feasible tool to stratify clinically significant liver disease in community alcohol services. It can stimulate a change in high-risk drinking behaviour and a normal liver stiffness result does not provide false reassurance to participants. 

P97 Transient elastography in community alcohol services: can it be an adjunct and impact drinking behaviour?

Rekonstruktion von Leistungssportkarrieren

e ISOPAR method is a method for characterizing the difficulty of golf holes and allows the performance of shots to be analyzed. emethod is based on the ball locations provided by ShotLinkTMand the subsequent number of shots required to hole out from each respective location. ISOPAR values are calculated which represent the number of shots the field would require to hole out. ese ISOPAR values can, a) be visualized on an ISOPAR map and, b) lead to a new performance indicator called Shotality, which is the difference between the ISOPAR values of the starting position and finishing position, respectively. e Shot ality score can also be used to determine how many shots were saved per shot, or per type of shot, with respect to the performance of the field.

http://i.cdn.turner.com/pgatour/docs/pdf/adp-isopar.pdf

e ISOPAR Method


Before the 2016/17 season, the International Ski Federation conducted major changes to its starting lottery, which defines the starting order in advance of each race of the speed disciplines. As part of this change, the top seeded athletes from then on were able to pick a starting position. Therefore, the aim of this study is two-folded. First, we explored the pick behavior of the top athletes and analyzed if they were able to identify favorable starting positions. Second, we investigated the influence of the rule change on competitive balance. Our sample consisted of 322 races with 17,725 individual performances of the seasons 2011/2012 to 2020/2021 and all our analysis were run separately for Women’s Downhill, Women’s Super G, Men’s Downhill and Men’s Super G. We could show that for all disciplines and both genders athletes heavily preferred to start around starting position 7. To start from such positions only led to significantly better rankings in Men’s Super G (z = 2.04, p = .041), but common language effect size showed the same trend for Women’s Super G (CL: 51.9%) as well as Men’s (CL: 53.3%) and Women’s Downhill (CL: 53.6%) competitions. In addition, male starters seeded among the top 7 performed significantly better after the rule change (Downhill: z = 2.95, p = .002; Super G: z = 2.89, p = .002), whereas they performed worse in Women’s Super G (z = -2.77, p = .005). Our findings indicate that there is a change in competitive balance for men’s competitions but not for women’s competitions. In addition, combining these findings with the detected picking preferences of the top athletes, we conclude our work with suggestions for further adaptions of the starting lottery.
 


Martin Lames

Papers

Implementation of Recurrence Analysis algorithms in a dashboard for practical application in Football

P97 Transient elastography in community alcohol services: can it be an adjunct and impact drinking behaviour?

Rekonstruktion von Leistungssportkarrieren

e ISOPAR Method

Impact of the revised starting lottery in the alpine speed events on performance of the top athletes