Abstract: In displacement measurements by far-field photography, the scale between object and image has to be calibrated. The calibration can be carried out by placing a rule at the position of the object. In practice, however, this is usually not possible. Especially the orientation of the rule is difficult to set precisely. In this research, a calibration method is proposed by use of equilateral polygon, which can be the hat of a bolt. The authors prove the equilateral polygons that have the same front projection are congruent. Therefore, the size of the equilateral polygon can be uniquely extracted by its front-projection image and the photogrammetric calibration can be done accordingly. This calibration method is successfully implemented in a field measurement of the wind-induced vibration of a structure.

Key words: photogrammetry, object-image relation, calibration

摘要： 远景摄影测量物体位移时，需要标定物像之间的比例关系。标定可以通过在目标位置处放置一个已知方位角的标尺来完成，但是在实践中，标尺的放置和方位角的测量常常是有困难的。作者提出了一种利用正多边形物体进行摄影标定的方法，证明了具有同一正投影像的正多边形是全等的。据此，可以由正多边形物体的正投影像提取原像的尺寸，实现物像关系的标定。该方法成功地应用于某标志性建筑物风致振动的现场测量。

关键词: 摄影测量, 物像关系, 标定