基于形函数的隧道衬砌内壁影像展平方法及其应用

通过透视变换和四边形八节点形函数变换2种平面变换方法即可建立影像像素与展平坐标系之间的关系,生成基于影像的展开图,提出一种基于形函数的隧道衬砌影像展平变换方法。通过数值模拟测试,得出展平照片的误差分布以及不同拍摄位置对误差的影响。最后通过案例给出方法实际应用的效果。结果表明：基于形函数变换的展平方法反需要衬砌表面照片及照片中8个控制点的展平坐标即能建立隧道影像与展开平面之间的坐标关系。该方法所产生的误差很小,具有较高的实用性。

A method for tunnel lining surface photo flattening based on shape functions transform

An image transform method for flattening tunnel lining photo was proposed in this paper based on shape functions transform. It would be convenient to build tunnel lining expansion plan on the basis of flattened image,for it only use two plane transform methods i. e.,perspective transform and eight nodes shape functions transform. Feasibility of the method was validated through numerical simulation. Meanwhile,the errors distribution of flattened image and the influence of errors at different shot position were also obtained. Finally,examples were given to show the effect of the method utilized the in practical application. The results show that,based on flattening of shape functions transform,the coordinate relationship between tunnel photos and the flattening plane can be established with tunnel lining surface photo and flattening coordinates of eight control points of photo. The error of this method is small,which shows good practicality.