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数字图像技术的最新发展将促进立体显示的实现,它使得在数字领域对立体图像进行高效处理和编码成为可能.立体图像显示已经应用于教育、医疗和娱乐等领域.反过来这些图像应用领域又促进了立体显示技术的发展.不管采用何种方式处理立体显示数据,因显示系统的终端为观察者,它必须以某种方式将正确的图像展现到观察者与其对应的眼前.一种简单经济的方法就是时分转换法.对应于左眼和右眼的图像在一个刷新周期内交替出现.观察者戴着光阀眼镜,当左眼图像显示时,左眼光阀被打开使图像通过,此时右眼光阀处于关闭状态阻止图像通过.当右眼图像显示时,光阀操作过程正好相反.这样,在立体显示中左眼只见到左眼图像,右眼只见到右眼图像.当观察者的眼睛位置随着其头部运动而发生变化时,应回馈其变化以调整左眼和右眼的图像使观察不受影响.此文介绍一种应用超声波传感器构成的简单的、低成本的显示头跟踪器.置于眼镜上的超声波发射器发送信号,其显示屏上3个超声波接收器(呈三角形放置)接收信号.根据从发射信号到接收信号的时间间隔可以计算出头部位置.介绍了硬件结构、实验数据分析及校正算法.最后讨论了虚拟现实应用未来研究方向,即改善眼睛舒适度的自由观看系统.

The development of digital imaging system will facilitate the practical implementation of the long-known concept of binocular imaging. Efficient processing and coding of binocular imagery are possible in the digital domain. Binocular imagery has applications in education, medicine and entertainment, to name a few. And the proliferation of stereoscopic display is currently gaining impetus from the activities. Regardless of applications or processing method, any stereoscopic display system whose end-user is a person must have some method of presenting the correct image to only the eye intended for it. A simple and economical method is known as time-division multiplexing. The left and right-eye images(stereoscopic image pair) are alternately displayed once a vertical refresh period. The viewer wears an optical shutter. While left-eye image is displayed, the shutter in front of the left eye is "open" and allows light to pass through it. During the time the right eye shutter is "closed" and light transmission is retarded. The shutters then reverse the operation when the right-eye image is displayed. In this way the left eye sees the left-eye images and the right eye sees the right-eye images of the stereoscopic image pair. When the eye position changes with the viewer's head movement, the position of the left and right image on the screen should be changed according to the head movement. In this paper a simple and low-cost head tracker using acoustic sensors is demonstrated . An acoustic transmitter which sends pulse signals is attached to the eye-glasses and three acoustic receivers which receive the pulse signals are attached to three triangle points of the display screen. According to the time duration of transmitter and receivers the head position can be calculated. Hardware configuration, experimental data analysis and calibrating algorithm are described in detail.