相对位置数据 meaning in Chinese

station-keeping data

The system takes the image of the eye of the tested subject when he is gazing at a position , and processes the eye image to get the relative position of the pupil in the eye , then calculates out the gaze position where he is gazing at
该系统对被测对象观察不同注视点时的眼睛进行成像，通过图像处理得到瞳孔在眼睛中的相对位置数据，从而计算出所观察的注视点的位置。