From Point Clouds to Architectural Models: Algorithms for Shape Reconstruction

Abstract

ABSTRACT:The use of terrestrial laser scanners in architectural survey applications has become more and more common. Row data complexity, as given by scanner restitution, leads to several problems about design and 3D-modelling starting from Point Clouds. In this context we present a study on architectural sections and mathematical algorithms for their shape reconstruction, according to known or definite geometrical rules, focusing on shapes of different complexity. Each step of the semi-automatic algorithm has been developed using Mathematica software and CAD, integrating both programs in order to reconstruct a geometrical CAD model of the object. Our study is motivated by the fact that, for architectural survey, most of three dimensional modelling procedures concerning point clouds produce superabundant, but often unnecessary, information and are also very expensive in terms of cpu time using more and more sophisticated hardware and software. On the contrary, it's important to simplify/decimate the point cloud in order to recognize a particular form out of some definite geometric/architectonic shapes. Such a process consists of several steps: first the definition of plane sections and characterization of their architecture; secondly the construction of a continuous plane curve depending on some parameters. In the third step we allow the selection on the curve of some nodal points with given specific characteristics (symmetry, tangency conditions, shadowing exclusion, corners, … ). The fourth and last step is the construction of a best shape defined by the comparison with an abacus of known geometrical elements, such as moulding profiles, leading to a precise architectonical section. The algorithms have been developed and tested in very different situations and are presented in a case study of complex geometries such as some mouldings profiles in the Church of San Carlo alle Quattro Fontane.

New Contributions on the Dome of the Pantheon in Rome: Comparison Between the Ideal Model and the Survey Model

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Opportunities of Geometric Documentation of Historic Buildings with Terrestrial Laser Scanner, Examples from Aksaray/Turkey

“…Before any intervention, the restorer needs to get deep and complete knowledge of the cultural property such as measurement, shape and cultural values (Genovese, 2005). It contains different sort of data and is essential to have "accurate knowledge-based model" of the building which includes collected data related to building material, character, decays, interventions and restoration works in the past and information from archival studies about the structure (Canciani, 2013). Laser scanning technology helps to complete geometric and material data of the structure so it contributes to protect authenticity of historic structure by transferring this data significant for restoration (Versaci and Cardaci, 2011).…”

A new Gis-based map of villa Adriana, a multimedia guide for ancient paths

“…In each case, the principal objective is the study and conservation of the heritage site or monument and as such the most relevant aspects of this work are the 3D survey (Remondino, 2011), the advanced modelling (De Luca et al 2011;Canciani, 2013) connection of the metadata as three dimensional objects (Drap, 2009;Agugiaro, 2011) and more generally, the management and interpretation of all data obtained from excavations for the works of restoration and conservation (Ardissone, 2013). This type of data requires multi-layer instruments capable of connecting diverse data in order to help with study and decision making processes.…”