3D survey and BIM-ready modelling of a Greek Orthodox Church in Athens

Abstract

This paper explores the application of two widely-used digital technologies, Structure-from-Motion (SfM) photogrammetry and Building Information Modelling (BIM), in the case of Byzantine ecclesiastical architecture. SfM photogrammetry was used for the 3D documentation of Agioi Anargyroi Greek Orthodox church in Athens, including exterior and internal spaces, using a combination of ground-based and aerial (UAV-mounted) photography under rigorous survey control. The resulting point cloud dataset constitutes the primary survey record of the building in its current state (as-existing). Finally, a BIM-ready model of the existing structure was proposed as an alternative method for the production of coordinated 2D drawings and facilitating requirements of subsequent development of the project.

Introduction

In the last decade, Structure-from-Motion photogrammetry (SfM) has been used extensively as a method for 3D documentation of cultural heritage, ranging from large-scale landscapes, historic buildings, monuments, museum objects and artefacts. A growing range of SfM software applications are currently available to an expanding base of users in the heritage sector, corresponding with significant volume of academic research and publications in the field [1][2][3]. The use of SfM photogrammetry (along with other technologies such as laser scanning and close-range scanning) for the digitization of museum collections is becoming ever more widely practiced, as evidenced by the growing output of 3D digital models of cultural heritage objects in web-based 3D viewing and sharing platforms [4]. The relatively low starting costs, versatility and high-quality of visual output (textures) makes SfM photogrammetry an attractive solution for 3D recording of complex historic monuments. This paper looks at the application of SfM for the survey of a significant early example of Byzantine ecclesiastical architecture in Greece.

Building Information Modelling is a technology more widely used in the new-build construction industry. However, in the last five years, the concept of Heritage (or Historic) Building Information Modelling (HBIM) has become of hot topic for research, while in some countries relevant legislation encourages or even enforces the uptake of BIM by the heritage sector (mainly concentrating on construction projects involving historic buildings) [5][6]. Greece has no such legislation at the moment.

Unlike BIM for new-build, where the model develops along with the design and construction phases of a project, BIM for existing buildings (EBIM) and BIM for historic buildings (HBIM) generally requires a significant upfront investment of time and associated costs to create a fully developed as-existing BIM model, which represents not only the geometry but includes also material properties and other information about the various components of a building. The term ‘BIM-ready’ has been used to describe a 3D model created as an assembly of components in a BIM environment, which represents the geometry of the existing fabric, without incorporating any additional information [7].