Irsch Kristina, Ramey Nicholas A, Kurz Anton, Guyton David L, Ying Howard S
Krieger Children's Eye Center at The Wilmer Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-9028, USA.
Invest Ophthalmol Vis Sci. 2009 Mar;50(3):1152-7. doi: 10.1167/iovs.08-2739. Epub 2008 Oct 31.
To describe a video-based head-tracking technique to compensate for torsional, horizontal, and vertical in-plane head movements during pupil/iris-tracking video-oculography with a tilting haploscope.
Custom software was developed for image acquisition and off-line analysis for a novel haploscopic viewing device. Head movements were constrained to the frontal plane with the use of a bite plate and a forehead rest. Head movements were monitored by tracking black adhesive dots with a white border placed near the subject's inner canthi. Dot and pupil positions were computed using feature detection based on the Hough transform modified for ellipses. With the inter-dot distance and the relative vertical shifts of the dots during head motion, each video frame was rotated and translated to remove the effects of head movement from eye movement data. This technique was verified with a model head and with healthy subjects, who were asked to strain their heads purposefully against the bite plate during the recording. Head-tracker performance during 45 degrees head tilting was also assessed.
Validation experiments with the model head indicated a linear relationship, between true and measured positions, with a Pearson's correlation coefficient of R = 1.00. For human subjects, binocular video-oculographic recordings showed essential elimination of head movement artifacts from the recorded eye movements.
Tracking black dots placed near the inner canthi is an effective method of compensation for horizontal, vertical, and torsional in-plane head movements during pupil and iris crypt-based video-oculography.
描述一种基于视频的头部跟踪技术，以补偿在使用倾斜双目间接检眼镜进行瞳孔/虹膜跟踪视频眼震描记术期间头部的扭转、水平和垂直平面内运动。
为一种新型双目间接检眼镜观察设备开发了用于图像采集和离线分析的定制软件。使用咬板和前额托将头部运动限制在额平面内。通过跟踪放置在受试者内眦附近的带有白色边框的黑色粘性点来监测头部运动。使用基于为椭圆修改的霍夫变换的特征检测来计算点和瞳孔的位置。根据点之间的距离以及头部运动期间点的相对垂直位移，对每个视频帧进行旋转和平移，以从眼动数据中消除头部运动的影响。该技术在模型头部和健康受试者身上得到验证，要求健康受试者在记录过程中有意识地将头部靠在咬板上。还评估了45度头部倾斜期间头部跟踪器的性能。
对模型头部的验证实验表明，真实位置与测量位置之间存在线性关系，皮尔逊相关系数R = 1.00。对于人类受试者，双眼视频眼震描记记录显示记录的眼动中基本消除了头部运动伪影。
跟踪放置在内眦附近的黑点是在基于瞳孔和虹膜隐窝的视频眼震描记术期间补偿水平、垂直和扭转平面内头部运动的有效方法。
