平面约束的近景影像绝对定向方法及其精度

The method of plane-constrained absolute orientation for close-range images

针对特殊环境难以布设控制点来求解绝对定向参数的问题,该文提出一种基于空间平面约束的绝对定向方法。该方法利用激光水平仪投射的水平线和铅垂线确定水平面和铅垂面,基于水平面和铅垂面的空间约束来确定立体模型的旋转角,利用物方已知长度的线段确定模型比例尺。经普通数码相机获取立体像对的实验,结果表明摄影距离为3 m时定向后模型坐标精度约6 mm,摄影距离为6 m时定向后模型坐标精度约9 mm,摄影距离为12 m时定向后模型坐标精度约2 cm;定向后模型坐标的相对精度则随着拍摄距离的增加没有加大,精度保持良好。该方法可用于室内测量和地下空间测量,具有实用价值。

Aiming for solving absolute orientation parameters in some special environments was difficult as it was too hard to lay out control points,this paper presented an absolute orientation method based on spatial plane constraints.The method used the horizontal line and the vertical line projected by the laser level to determine the horizontal plane and the vertical plane,and used the horizontal plane and the vertical plane to perform spatial constraint to solve the rotation angle of the three-dimensional model,and the line scale of the known length of the object was used to solve the model scale.The experiment of obtaining stereo image pairs by ordinary digital camera showed that the coordinate accuracy of the model after orientation was about 6 mm when the photographic distance was 3 m,the coordinate accuracy of the model was about 9 mm when the photographic distance was 6 m,and the coordinate accuracy of the model was about 2 cm when the photographic distance was 12 m;the relative accuracy of the model coordinates after orientation was not increased with the increase of the shooting distance,and the precision was kept good.Experiments showed that the method could be used for indoor measurement and underground space measurement,and had practical value.