Action Sport Cameras As An Instrument To Perform A 3d Underwater Motion Analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Action sport cameras (ASC) are currently adopted mainly for entertainment purposes but their uninterrupted technical improvements, in correspondence of cost decreases, are going to disclose them for three-dimensional (3D) motion analysis in sport gesture study and athletic performance evaluation quantitatively. Extending this technology to sport analysis however still requires a methodologic step-forward to making ASC a metric system, encompassing ad-hoc camera setup, image processing, feature tracking, calibration and 3D reconstruction. Despite traditional laboratory analysis, such requirements become an issue when coping with both indoor and outdoor motion acquisitions of athletes. In swimming analysis for example, the camera setup and the calibration protocol are particularly demanding since land and underwater cameras are mandatory. In particular, the underwater camera calibration can be an issue affecting the reconstruction accuracy. In this paper, the aim is to evaluate the feasibility of ASC for 3D underwater analysis by focusing on camera setup and data acquisition protocols. Two GoPro Hero3+ Black (frequency: 60Hz; image resolutions: 1280x720/1920x1080 pixels) were located underwater into a swimming pool, surveying a working volume of about 6m(3). A two-step custom calibration procedure, consisting in the acquisition of one static triad and one moving wand, carrying nine and one spherical passive markers, respectively, was implemented. After assessing camera parameters, a rigid bar, carrying two markers at known distance, was acquired in several positions within the working volume. The average error upon the reconstructed inter-marker distances was less than 2.5mm (1280x720) and 1.5mm (1920x1080). The results of this study demonstrate that the calibration of underwater ASC is feasible enabling quantitative kinematic measurements with accuracy comparable to traditional motion capture systems.118Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (Sao Paulo Research Foundation) [00/1293-1, 2006/02403-1, 2009/09359-6]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (National Counsel of Technological and Scientific Development) [473729/2008-3, 304975/2009-5, 478120/2011-7, 234088/2014-1, 481391/2013-4]Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (Brazilian Federal Agency for Support and Evaluation of Graduation Education) [2011/10-7, 08/2014]Fundacao de Amparo a Pesquisa de Minas Gerais (Minas Gerais Research Foundation) [PEE-00596-14]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Markerless 3D human pose tracking through multiple cameras and AI: Enabling high accuracy, robustness, and real-time performance

Tracking 3D human motion in real-time is crucial for numerous applications across many fields. Traditional approaches involve attaching artificial fiducial objects or sensors to the body, limiting their usability and comfort-of-use and consequently narrowing their application fields. Recent advances in Artificial Intelligence (AI) have allowed for markerless solutions. However, most of these methods operate in 2D, while those providing 3D solutions compromise accuracy and real-time performance. To address this challenge and unlock the potential of visual pose estimation methods in real-world scenarios, we propose a markerless framework that combines multi-camera views and 2D AI-based pose estimation methods to track 3D human motion. Our approach integrates a Weighted Least Square (WLS) algorithm that computes 3D human motion from multiple 2D pose estimations provided by an AI-driven method. The method is integrated within the Open-VICO framework allowing simulation and real-world execution. Several experiments have been conducted, which have shown high accuracy and real-time performance, demonstrating the high level of readiness for real-world applications and the potential to revolutionize human motion capture.Comment: 19 pages, 7 figure

A SWOT Analysis of Portable and Low-Cost Markerless Motion Capture Systems to Assess Lower-Limb Musculoskeletal Kinematics in Sport

Markerless motion capture systems are promising for the assessment of movement in more real world research and clinical settings. While the technology has come a long way in the last 20 years, it is important for researchers and clinicians to understand the capacities and considerations for implementing these types of systems. The current review provides a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis related to the successful adoption of markerless motion capture technology for the assessment of lower-limb musculoskeletal kinematics in sport medicine and performance settings. 31 articles met the a priori inclusion criteria of this analysis. Findings from the analysis indicate that the improving accuracy of these systems via the refinement of machine learning algorithms, combined with their cost efficacy and the enhanced ecological validity outweighs the current weaknesses and threats. Further, the analysis makes clear that there is a need for multidisciplinary collaboration between sport scientists and computer vision scientists to develop accurate clinical and research applications that are specific to sport. While work remains to be done for broad application, markerless motion capture technology is currently on a positive trajectory and the data from this analysis provide an efficient roadmap toward widespread adoption

Repeatability of Motion Health Screening Scores Acquired from a Three-Dimensional Markerless Motion Capture System

The purpose of the present study was to examine the repeatability of five algorithm-derived motion health screening scores (i.e., readiness, explosiveness, functionality, quality, and dysfunction) obtained from an innovative three-dimensional markerless motion capture system, composed of eight high-definition cameras recording at 60 fps. Thirteen females and six males performed two sets of three motion capture screenings, separated one week apart (six in total). The screenings consisted of 20 body movements performed in sequential order. Each screening within a testing session was separated by a 30 min rest interval to avoid the possible influence of fatigue. A trained research team member, facing the participant and standing outside of the camera capture range, was present to demonstrate each individual movement. The order in which motions were performed was identical across all participants. Repeated measures analysis of variance and intraclass correlation coefficients were used to examine statistically significant differences and measurement agreement across six testing sessions. The findings of the present study revealed no significant differences in algorithm-based motion health screening scores across multiple testing sessions. Moreover, excellent measurement reliability was found for readiness scores (ICC, 95% CI; 0.957, 0.914–0.980), good-to-excellent for functionality (0.905, 0.821–0.959) and explosiveness scores (0.906, 0.822–0.959), and moderate-to-excellent for dysfunction (0.829, 0.675–0.925) and quality scores (0.808, 0.635–0.915)

The development and evaluation of virtual reality-based training on performance and rehabilitation outcomes

Sports injuries are types of injuries that usually occur during sports, training, or exercise. Sports injuries often result from poor training methods, inappropriate equipment, lack of fitness, insufficient warm-up, and trauma (Salerno, 2009). Knee injuries are considered one of the most common injuries in athletes and include a large part of the cost of medical care for sports injuries (Loes et al., 2000; Sancheti et al., 2010). The ACL is the most common knee ligament injury in rugby, soccer, ski, volleyball, gymnastics, and basketball players due to quick deceleration movements such as landing, pivoting, cutting, and changing direction in these sports. Despite increased knowledge of ACL injury mechanisms, rehabilitation programmes and surgical techniques, the rates of return-to-sport (RTS) and the subsequent ACL re-injury after ACL reconstruction (ACLR) are not optimal (Buckthorpe, 2019). Therefore, rehabilitation plays a significant role in helping athletes return to sports activities, and inappropriate rehabilitation can even devastate a satisfactory ACLR (Wright et al., 2015). This dissertation consists of two studies, including a systematic review in Chapter 2 that explores the research conducted on the application of immersive technologies for improving the outcome of the rehabilitation phases after ACL reconstruction and examines the correlation between virtual reality, rehabilitation, exercise therapy, and sport-related ACL injuries in patients. The second study in Chapter 3 validates the Microsoft Azure Kinect camera for body tracking of dynamic movements against the gold standard Qualisys system. The findings indicated that VR-based systems could be a considerable alternative to real-world training to improve certain aspects of athletic performance because immersive technologies effectively offer a tool to control virtual environmental features. Finally, immersive technologies and VR-based systems are still in their infancy and will need considerable improvements in the future. Therefore, further research needs to be conducted in a theoretical frame to acknowledge the profitability of VR interventions in sports performance and rehabilitation programmes. The triple Azure Kinect system provides a consistent track of the joint centres' displacements with good to excellent agreement in the vertical and AP direction during the squat exercise in all joints except the ankles, particularly in upper joints such elbow and shoulder. However, future investigations must be conducted to acknowledge the Azure Kinect's profitability in the assessment of abnormal clinical conditions and the limits of Kinect's accuracy in various movements and planes of motion. In conclusion, the markerless triple Azure Kinect motion capture system may be a considerable alternative to a gold standard Qualisys marker-based system for specific applications such as human activities in the frontal plane. However, future investigations must be conducted to acknowledge the Azure Kinect's profitability in the assessment of abnormal clinical conditions and the limits of Kinect's accuracy in various movements and planes of motion

Determining Relationships Between Kinematic Sequencing and Baseball Pitch Velocity Using pitchAITM

Professional baseball pitchers have consistently been increasing pitch velocity since 2008 (the first year of automated pitch tracking and classification at all 30 MLB stadiums) and increasing the number of pitches thrown over 95mph (Sullivan, 2019). Fastball velocity is a primary risk factor for elbow injuries as there is a general linear relationship with increased elbow torques (Aguinaldo & Chambers, 2009; Chalmers et al., 2016; Slowik et al., 2019). The kinematic sequence has been referred to as the order and magnitude of joint angular velocities during the pitch delivery and has been associated with pitch velocity and elbow torque (Nicholson et al., 2022a, 2022b; Scarborough, Leonard, et al., 2021). The purpose of the research was to identify kinematic sequence metrics associated with pitch velocity and use them to predict pitch velocity using pitchAITM (Dobos et al., 2022). A total of 80 pitchers (187.2 ± 8.2 cm, age 20.1 ± 3.3 years) ranging in skill level from high school to professional baseball participated in this study. Video for pitchAITM, player height and weight were collected at 2 baseball training facilities. Extracted pitchAITM data included the peak magnitudes and relative timings of pelvis rotation velocity, trunk rotation velocity, elbow extension velocity, and shoulder internal rotation velocity. Average pitch velocity in the data set was 85.3 ± 5.7 mph or 38.1 ± 2.5 m/s. Pitch velocity was predicted using both a multilinear regression, as well as a custom neural network model. The multilinear regression generated a significant prediction for pitch velocity with an R2 = 0.368 and p < 0.01. Pitcher weight (β = 0.535, p < 0.001), peak pelvis rotational velocity timing (β = -0.157, p = 0.001), peak elbow extension timing (β = 0.122, p = 0.006), and peak shoulder internal rotation timing (β = -0.113, p = 0.018), were significant contributors to the multilinear model. The neural network model significantly predicted velocity with an R2 = 0.372, p < 0.01. Actual and predicted velocity were not significantly different (p = 0.353). In conclusion, pitchAITM kinematic sequencing can predict pitch velocity using both a multilinear regression and custom neural network

Video capture and post-processing technique for approximating 3D projectile trajectory

In this paper we introduce a low-cost procedure and methodology for markerless projectile tracking in three-dimensional (3D) space. Understanding the 3D trajectory of an object in flight can often be essential in examining variables relating to launch and landing conditions. Many systems exist to track the 3D motion of projectiles but are often constrained by space or the type of object the system can recognize (Qualisys, Göteborg, Sweden; Vicon, Oxford, United Kingdom; Opti-Track, Corvallis, Oregon USA; Motion Analysis, Santa Rosa, California USA; Flight Scope, Orlando, Florida USA). These technologies can also be quite expensive, often costing hundreds of thousand dollars. The system presented in this paper utilizes two high-definition video cameras oriented perpendicular to each other to record the flight of an object. A postprocessing technique and subsequent geometrically based algorithm was created to determine 3D position of the object using the two videos. This procedure and methodology was validated using a gold standard motion tracking system resulting in a 4.5 ± 1.8% deviation from the gold standard

Video capture and post-processing technique for approximating 3D projectile trajectory

In this paper we introduce a low-cost procedure and methodology for markerless projectile tracking in three-dimensional (3D) space. Understanding the 3D trajectory of an object in flight can often be essential in examining variables relating to launch and landing conditions. Many systems exist to track the 3D motion of projectiles but are often constrained by space or the type of object the system can recognize (Qualisys, Göteborg, Sweden; Vicon, Oxford, United Kingdom; Opti-Track, Corvallis, Oregon USA; Motion Analysis, Santa Rosa, California USA; Flight Scope, Orlando, Florida USA). These technologies can also be quite expensive, often costing hundreds of thousand dollars. The system presented in this paper utilizes two high-definition video cameras oriented perpendicular to each other to record the flight of an object. A postprocessing technique and subsequent geometrically based algorithm was created to determine 3D position of the object using the two videos. This procedure and methodology was validated using a gold standard motion tracking system resulting in a 4.5 ± 1.8% deviation from the gold standard

In-Vivo Investigation of the Medial Longitudinal Arch of the Foot and Orthotic Interactions using Bi-Planar Fluoroscopy

Orthotic devices are a conservative treatment for common disorders of the foot and ankle such as pes planus and pes cavus. It is thought that orthotics change the kinematics of the foot by applying forces and constraint on the plantar surface, which can act to change body biomechanics and correct for malalignment in the legs and trunk. This thesis compares the angle of the medial longitudinal arch (MLA) between three foot types: pes planus (low arch), pes cavus (high arch) and normal arch, during barefoot and shoed walking, and walking with orthotics. In-vivo bi-planar fluoroscopy was used with markerless radiostereometric analysis (RSA) to measure an angle that defines the MLA with the greatest accuracy to date. MLA angles were significantly smaller (

Markerless Kinematics of Pediatric Manual Wheelchair Mobility

Pediatric manual wheelchair users face substantial risk of orthopaedic injury to the upper extremities, particularly the shoulders, during transition to wheelchair use and during growth and development. Propulsion strategy can influence mobility efficiency, activity participation, and quality of life. The current forefront of wheelchair biomechanics research includes translating findings from adult to pediatric populations, improving the quality and efficiency of care under constrained clinical funding, and understanding injury mechanisms and risk factors. Typically, clinicians evaluate wheelchair mobility using marker-based motion capture and instrumentation systems that are precise and accurate but also time-consuming, inconvenient, and expensive for repeated assessments. There is a substantial need for technology that evaluates and improves wheelchair mobility outside of the laboratory to provide better outcomes for wheelchair users, enhancing clinical data. Advancement in this area gives physical therapists better tools and the supporting research necessary to improve treatment efficacy, mobility, and quality of life in pediatric wheelchair users. This dissertation reports on research studies that evaluate the effect of physiotherapeutic training on manual wheelchair mobility. In particular, these studies (1) develop and characterize a novel markerless motion capture-musculoskeletal model systems interface for kinematic assessment of manual wheelchair propulsion biomechanics, (2) conduct a longitudinal investigation of pediatric manual wheelchair users undergoing intensive community-based therapy to determine predictors of kinematic response, and (3) evaluate propulsion pattern-dependent training efficacy and musculoskeletal behavior using visual biofeedback.Results of the research studies show that taking a systems approach to the kinematic interface produces an effective and reliable system for kinematic assessment and training of manual wheelchair propulsion. The studies also show that the therapeutic outcomes and orthopaedic injury risk of pediatric manual wheelchair users are significantly related to the propulsion pattern employed. Further, these subjects can change their propulsion pattern in response to therapy even in the absence of wheelchair-based training, and have pattern-dependent differences in joint kinematics, musculotendon excursion, and training response. Further clinical research in this area is suggested, with a focus on refining physiotherapeutic training strategies for pediatric manual wheelchair users to develop safer and more effective propulsion patterns