基于多层中轴点拟合的古塔变形检测

Deformation Detection and Estimation of Pagoda Based on Multilayer Central Points’ Fitting

摘要:

提出一种新的古塔倾斜测量及质量评价方法.针对古塔层层收分、斗拱檐口及棱角模糊导致变形测量特征点难以确定的问题，提出利用圆拟合的方法确定古塔各层中轴点.在古塔中心轴线拟合中，引入整体最小二乘法进行平差解算，克服了系数矩阵存在误差的问题.除计算古塔整体倾斜度，还计算各层倾斜度和扭曲度以反映古塔的详细变形情况.相比传统的简单利用塔顶和基座的相对位移和塔高来计算古塔倾斜的变形检测方法，采用多层中轴点拟合的检测方法更加准确和详细地反映了古塔的变形.

Abstract:

This paper presents a practical novel approach for tilt measurement of ancient pagodas and the criterion quality evaluation. Due to the characteristics (multieaves, dougong and vague edges) of ancient pagodas, it is difficult to select measurement points. The coordinates of the central point of each floor of the ancient pagoda structure is estimated by using the method of ellipse fitting. During the process of fitting space axis of the pagoda, the method of total least square is applied to calculate the result. Besides the inclination and twist of each floor is calculated in order to assess the quality of the pagoda in a comprehensive way. This method is more accurate and detailed than the current tilt measurement method which determines the deformation and inclination of tower structures by the ratio of relative displacement of the tower’s base and top and the height of the tower.