Clarke A H, Ditterich J, Drüen K, Schönfeld U, Steineke C
Free University of Berlin, Berlin, Germany.
Behav Res Methods Instrum Comput. 2002 Nov;34(4):549-60. doi: 10.3758/bf03195484.
A novel three-dimensional eye tracker is described and its performance evaluated. In contrast to previous devices based on conventional video standards, the present eye tracker is based on programmable CMOS image sensors, interfaced directly to digital processing circuitry to permit real-time image acquisition and processing. This architecture provides a number of important advantages, including image sampling rates of up to 400/sec measurement, direct pixel addressing for preprocessing and acquisition,and hard-disk storage of relevant image data. The reconfigurable digital processing circuitry also facilitates inline optmization of the front-end, time-critical processes. The primary acquisition algorithm for tracking the pupil and other eye features is designed around the generalized Hough transform. The tracker permits comprehensive measurement of eye movement (three degrees of freedom) and head movement (six degrees of freedom), and thus provides the basis for many types of vestibulo-oculomotor and visual research. The device has been qualified by the German Space Agency (DLR) and NASA for deployment on the International Space Station. It is foreseen that the device will be used together with appropriate stimulus generators as a general purpose facility for visual and vestibular experiments. Initial verification studies with an artificial eye demonstrate a measurement resolution of better than 0.1 degrees in all three components (i.e.,system noise for each of the components measured as 0.006 degrees H, 0.005 degrees V, and 0.016 degrees T. Over a range of +/-20 degrees eye rotation, linearity was found to be <0.5% (H), <0.5% (V), and <2.0% (T). A comparison with the scleral search coil technique yielded near equivalent values for the system noise and the thickness of Listing's plane.
本文介绍了一种新型三维眼动仪，并对其性能进行了评估。与以往基于传统视频标准的设备不同，该眼动仪基于可编程CMOS图像传感器，直接与数字处理电路相连，以实现实时图像采集和处理。这种架构具有许多重要优势，包括高达400帧/秒的图像采样率、用于预处理和采集的直接像素寻址，以及相关图像数据的硬盘存储。可重构数字处理电路还便于对前端关键时间进程进行在线优化。用于跟踪瞳孔和其他眼部特征的主要采集算法是围绕广义霍夫变换设计的。该眼动仪能够全面测量眼球运动（三个自由度）和头部运动（六个自由度），从而为多种前庭眼动和视觉研究提供了基础。该设备已获得德国航天局（DLR）和美国国家航空航天局（NASA）的认证，可部署在国际空间站上。预计该设备将与适当的刺激发生器一起用作视觉和前庭实验的通用设施。使用人工眼进行的初步验证研究表明，在所有三个分量上的测量分辨率均优于0.1度（即，每个分量的系统噪声测量值为0.006度水平、0.005度垂直和0.016度扭转）。在眼球旋转±20度的范围内，线性度在水平方向<0.5%、垂直方向<0.5%、扭转方向<2.0%。与巩膜搜索线圈技术的比较得出了系统噪声和利斯廷平面厚度的近似等效值。
