共查询到18条相似文献，搜索用时 187 毫秒
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三维影像分析控制点测量与坐标转换软件系统的设计与实现 总被引：1，自引：0，他引：1
三维运动影像分析通常采用的算法是直接线性变换法(DLT),而控制点的空间三维坐标是应用直接线性变换法进行标定基本参数,它目前是通过三维标定框架的已知控制点的坐标所获得的。由于三维标定框架所覆盖的空间有限,对于较大运动范围运动项目的三维运动影像分析会造成较大的误差。研究目的是在全站仪(Topcon GPT-3002 N)为硬件的基础上,以对象编程语言C#为开发工具开发了三维影像分析控制点测量与坐标转换软件系统。此系统为对运动空间任意布置的控制点,或标定框架上的控制点的三维坐标的精确测量提供了实用的工具,也为在运动技术诊断和分析中应用三维跟踪扫描影像分析方法奠定了基础。此外,还对控制点目标观测与坐标框架换算系统的需求、总体架构、数据库设计、算法设计、具体功能和应用实现等方面进行了较为详细的论述。 相似文献
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直接线性变换(DLT)算法是利用平面图像进行三维重构的基本算法,本文从框架位置的角度对三维重构的影响进行讨论,由此得出各个框架位置下控制点的平均相对误差,结果表明框架位置对三维重构具有一定的影响,同时相机角度对三雏重构具有深远的意义。 相似文献
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通过引入摄影机镜头的内、外方位元素的约束条件,导出了一种修正的DLT(MDLT)方法。该方法用于影片和录相的实测,得到一些有意义的结果。当测量的标定控制点点数较少(6～8个),且这些点的位置在空间和成像面分布不均匀时,用MDLT计算的结果比DLT的结果要好,误差可降低80％以上。 相似文献
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在人体运动的分析中,提取运动信息是必须的。对于人体运动的三维分析,图像系统常常是利用二维图像作三维重构,然后根据重构数据进行运动学、动力学分析。在重构技术中DLT算法由于其众多优点而得到了广泛应用。但是,由于人的运动是复杂而精细的,三维重构误差对运动分析误差的影响成为三维分析研究的关键点。针对三维重构所引起的误差,讨论了如何通过有效的方法来减小误差,以提高三维解析数据的精度,并提出了相关的方法和措施,为编制三维解析系统时提高精度提供可靠的理论依据。 相似文献
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在实验研究的基础上,对运动影像测量方法的误差问题进行了讨论.在总结前人研究结果以及实验测试的基础上,以竞走项目为例,提出了对测量过程中各误差源进行误差合成计算的方法,确定了最后测量结果的误差范围以及各误差源的比例构成.研究结果表明:在平面定机拍摄时,图像边缘处的镜头畸变误差会对测量结果产生一定影响;在立体影像定机拍摄时,标定空间与地面垂直方向的测量精度高于其他方向.误差合成的计算结果表明,平面定机拍摄和立体定机拍摄两种方法的测量精度分别为8.1±8.44 mm和8.05±4.9mm,多数被测点的位移量误差百分比在2％以下. 相似文献
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对此前有关影像测量误差的研究成果和结论进行总结,认为影像测量误差的主要来源为人因误差、环境误差和装置误差等几个方面,并可分为系统误差和随机误差两类。另外,对确定影像测量精度的方法进行归纳总结,主要可分为理论分析法和实验测试法。还对减小影像测量误差的方法进行归纳,消除系统误差的主要方法有:粘贴皮肤标志点法、设置参照点法、周期运动对侧关节点计算法、局部拍摄法以及同步多框架分析标定技术等;消除随机误差的主要方法是对原始数据的平滑。 相似文献
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从理论上介绍了鱼类摆尾技术的流体力学研究成果,并在实践中与运动员蝶泳腿技术分析相结合,指出水下蝶泳打腿(UUS,亦称水下波动游泳)的运动学、动力学特征以及在游泳出发、转身和划水过程中的应用. 相似文献
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三维影像分析是运动生物力学的重要研究手段之一,广泛地应用于运动技术分析和诊断中.三维跟踪扫描影像分析方法就是摄像机跟踪运动目标来记录运动的图像,并通过专门的图像解析系统解算得到运动目标空间实际三维坐标的方法.应用SIMI Motion的Pan/Tilt/Zoom功能来实现三维跟踪扫描录像分析,并对所得到的三维测量数据的精度进行评价和分析.研究结果表明,在相同的坐标参考系下,由全站仪和影像分析测量得到的24个点的三维空间绝对坐标的平均相差值为0.018±0.003 m,三维跟踪扫描影像测量的相对误差可以达到1.97%,这样的测量精度可满足运动技术分析的要求.介绍了实现三维跟踪扫描影像分析的全过程,对影响测量精度的因素进行了初步的分析,并提出了应采取的相应措施. 相似文献
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Tony Monnet Mathias Samson Anthony Bernard Laurent David Patrick Lacouture 《Sports Engineering》2014,17(3):171-181
Current trends in swimming biomechanics are focused on accurate measurements. Nowadays, reliable calibration methods have been proposed to reach an accuracy of about 1 mm on rigid structure. But the question remains about the final accuracy for three-dimensional hand kinematics measurement during the underwater phase of front crawl swimming. Furthermore, most research is based on manual tracking with two or more cameras. In this paper we propose a protocol to acquire three-dimensional hand kinematics when swimming in a specific pool with a motion analysis system behind windows. Results highlight the benefits of using such a system in terms of accuracy and feasibility: the time allowed for post-processing is ten times lower and the quantified improved accuracy is better than with manual tracking. 相似文献
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Young‐Hoo Kwon Jeffrey B. Casebolt 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):315-340
One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water‐air interface plane (glass) owing to the density difference. Camera calibration‐reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction‐induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a thorough review of: the nature of the refraction‐induced image deformation and its behaviour in underwater object‐space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration‐reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration‐reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double‐plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction. 相似文献
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Young‐Hoo Kwon Jeffrey B. Casebolt 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):95-120
One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water‐air interface plane (glass) owing to the density difference. Camera calibration‐reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction‐induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a through review of: the nature of the refraction‐induced image deformation and its behaviour in underwater object‐space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration‐reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration‐reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double‐plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction 相似文献
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Effects of light refraction on the accuracy of camera calibration and reconstruction in underwater motion analysis 总被引：1，自引：0，他引：1
Kwon YH Casebolt JB 《Sports biomechanics / International Society of Biomechanics in Sports》2006,5(2):315-340
One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water-air interface plane (glass) owing to the density difference. Camera calibration-reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction-induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a thorough review of: the nature of the refraction-induced image deformation and its behaviour in underwater object-space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration-reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration-reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double-plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction. 相似文献
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Kwon YH Casebolt JB 《Sports biomechanics / International Society of Biomechanics in Sports》2006,5(1):95-120
One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water-air interface plane (glass) owing to the density difference. Camera calibration-reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction-induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a through review of: the nature of the refraction-induced image deformation and its behaviour in underwater object-space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration-reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration-reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double-plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction. 相似文献
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Stefano Ceccon Elena Ceseracciu Zimi Sawacha Giorgio Gatta Matteo Cortesi Claudio Cobelli 《Journal of sports sciences》2013,31(3):276-287
Abstract Kinematic analysis of swimming is of interest to improve swimming performances. Although the video recordings of underwater swimmers are commonly used, the available methodologies are rarely precise enough to adequately estimate the three dimensional (3D) joint kinematics. This is mainly due to difficulties in obtaining the required kinematic parameters (anatomical landmarks, joint centres and reference frames) in the swimming environment. In this paper we propose a procedure to investigate the right upper limb’s 3D kinematics during front crawl swimming in terms of all elbow and shoulder degrees of freedom (three rotations of the shoulder, two of the elbow). The method is based upon the Calibrated Anatomical Systems Technique (CAST), a technique widely used in clinics, which allows estimation of anatomical landmarks of interest even when they are not directly visible. An automatic tracking technique was adopted. The intra-operator repeatability of the manual tracking was also assessed. The root mean squared difference of three anatomical landmarks, processed five times, is always lower than 8 mm. The mean of the root mean squared difference between trajectories obtained with the different methodologies was found to be lower than 20 mm. Results showed that complete 3D kinematics of at least twice as many frames than without CAST can be reconstructed faster and more precisely. 相似文献
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The purpose of this study was to use three-dimensional methods to determine whether there are distinct kinematic differences between sprint and distance front crawl swimmers when swimming at a sprint pace. Seven sprint and eight distance specialists performed four 25-m sprints through a 6.75-m(3) calibrated space recorded by six gen-locked cameras. The variables of interest were: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, shoulder and hip roll angles, duration of stroke phases, and the time corresponding to particular events within the stroke cycle relative to hand entry. Differences between sprint and distance swimmers were assessed with an independent t-test for each variable, in addition to effect size calculations. Differences between sprint and distance front crawl swimmers were generally small and not significant when swimming at a sprint pace. Differences were limited to temporal aspects of the stroke cycle. These findings suggest that coaches should not train sprint and distance specialists differently in terms of technique development. 相似文献
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Silvia Fantozzi Andrea Giovanardi Fabrício Anício Magalhães Rocco Di Michele Matteo Cortesi Giorgio Gatta 《Journal of sports sciences》2016,34(11):1073-1080
The analysis of the joint kinematics during swimming plays a fundamental role both in sports conditioning and in clinical contexts. Contrary to the traditional video analysis, wearable inertial-magnetic measurements units (IMMUs) allow to analyse both the underwater and aerial phases of the swimming stroke over the whole length of the swimming pool. Furthermore, the rapid calibration and short data processing required by IMMUs provide coaches and athletes with an immediate feedback on swimming kinematics during training. This study aimed to develop a protocol to assess the three-dimensional kinematics of the upper limbs during swimming using IMMUs. Kinematics were evaluated during simulated dry-land swimming trials performed in the laboratory by eight swimmers. A stereo-photogrammetric system was used as the gold standard. The results showed high coefficient of multiple correlation (CMC) values, with median (first–third quartile) of 0.97 (0.93–0.95) and 0.99 (0.97–0.99) for simulated front-crawl and breaststroke, respectively. Furthermore, the joint angles were estimated with an accuracy increasing from distal to proximal joints, with wrist indices showing median CMC values always higher than 0.90. The present findings represent an important step towards the practical use of technology based on IMMUs for the kinematic analysis of swimming in applied contexts. 相似文献