摄影测量中大视角比例尺设计

Large angle scale design in photogrammetry

为了实现对大型槽式太阳能发电聚光器曲率及尺寸规格的监控测量,设计了一种新型用于数字近景工业摄影测量中的比例尺,实现了大视角全方位范围内拍摄的比例尺在像面中的准确识别。比例尺由温度系数小的长杆材料制成,其两端固定球心距离精确标定的回光反射球形标志和同轴圆环编码标志。对摄影测量像面图像处理,首先通过射影变换交比不变性原则确定像面编码标志的定位点,其次通过码值点获得码值,精确识别编码标志。最后利用已识别的编码标志和码值信息,结合射影变换交比不变性原则确定比例尺两端球形回光反射标志,实现比例尺的准确识别。实验结果表明,设计的新型比例尺,在沿着同轴圆环的圆周大视角方向拍摄获得的摄影测量像面图像,可以通过同轴圆环编码标志准确识别比例尺,可用于数字近景工业摄影测量中的比例尺的自动识别。

Energy power generation concentrator,a new type of scale for industrial photogrammetry is designed,which can realize accurate recognition of the scale of the image in automatically wide viewing angle. The scale is made of a long rod characterized by a low temperature coefficient,and fixed a retro-reflective coaxial ring coding signs and a retro-reflective spherical which are accurately calibrated their length between them at both ends. Image processing for photogrammetry,the positioning point of the image coding mark is determined by the principle of perspective transform invariance of cross ratio. Secondly,identify the coding sign precisely by obtaining the code value from coding points. Finally,using the identified coding mark and code value information,combined with the principle of perspective transformation invariance of cross ratio,determine the retro-reflective spherical which is fixed at ends of the scale,to realize accurate identification of the scale. The experimental results show that through the design of the new scale,a photographic image is obtained by taking a large angle of view along the circumferential direction of the coaxial ring,it can identify the scale precisely based on the identification of the coaxial ring coding mark. The scale can be used for automatic recognition of scale in digital close range photogrammetry.