ABSTRACT

Chimneys are architectural elements of difficult access and analysis in heritage buildings. This paper presents a method for automatic modelling of round brick chimneys and analysing their inclination, straightness and surface. The method uses as input data point clouds acquired with a Terrestrial Laser Scanner. Four chimneys have been surveyed on the north face of Bragança Dukes’ Palace in Guimarães, Portugal. The method consists of two main processes. First, the point cloud of each chimney is segmented into circumferential sections and adjusted to cylinders by applying Maximum Likelihood Sample Consensus. From the set of centroids, the inclination and the straightness of the chimney is estimated. Second, the point cloud chimney is segmented longitudinally and adjusted to finite planes. The distance estimation between the input point cloud and the modelled planes allows detecting the lack of bricks or mortar erosions. The proposed method allows estimating characteristics in chimneys even if the chimneys have not been completely acquired.

摘要

烟囱是遗产建筑中难以进入和分析的建筑元素。本文提出了一种圆砖烟囱的自动建模方法，并分析了它们的倾斜度、直线度和曲面。该方法使用地面激光扫描仪获取的点云作为输入数据。在葡萄牙吉马良斯的布拉干萨公爵宫的北面对四个烟囱进行了调查。该方法包括两个主要过程。首先，每个烟囱的点云被分割成圆周部分，并通过应用最大似然样本一致性调整为圆柱体。从一组质心，估计烟囱的倾斜度和直线度。其次，点云烟囱被纵向分割并调整到有限平面。输入点云和建模平面之间的距离估计允许检测砖块或砂浆侵蚀的缺失。所提出的方法允许估计烟囱中的特征，即使烟囱尚未完全获得。