Biomedical Sciences Department, University of Sassari, Sassari, Italy.
Gait Posture. 2011 Apr;33(4):532-7. doi: 10.1016/j.gaitpost.2011.01.003. Epub 2011 Feb 4.
A markerless technique is proposed and applied to estimate the two-dimensional joint kinematics of the shank and foot complex during the stance phase. Image sequences were acquired with a single camera from three healthy subjects while walking barefoot and with socks. Automatic segmentation of the shank and foot was performed to isolate the moving body from the background. A multi-rigid body model for the shank and foot complex, with the relevant segment anatomical axes, was defined and an image cross-correlation technique was applied to detect the anatomical axes locations throughout the movement. The proposed markerless technique was validated by acquiring the same trials also with a stereophotogrammetric marker-based system and a simple marker set. Differences in the joint kinematics estimates obtained with the two techniques fall in most cases within the intra-subject variability showing that, in selected applications, the markerless technique may replace more expensive and more experimental time demanding marker-based techniques.
提出并应用一种无标记技术来估计站立阶段小腿和足部复合结构的二维关节运动学。使用单个摄像机从三个健康受试者在赤脚和穿袜子行走时获取图像序列。自动对小腿和足部进行分割，将运动的身体与背景隔离开来。定义了一个用于小腿和足部复合结构的多刚体模型，以及相关的节段解剖轴，并应用图像互相关技术来检测整个运动过程中的解剖轴位置。通过使用立体摄影测量标记的基于系统和简单的标记集来获取相同的试验，验证了所提出的无标记技术。两种技术获得的关节运动学估计值的差异在大多数情况下都在个体内变异性范围内，这表明在某些应用中，无标记技术可能会替代更昂贵且需要更多实验时间的基于标记的技术。
