Semantic 3D Media and ContentA semantic-based platform for the digital analysis of architectural heritage
Graphical Abstract
Four “points of view” on the building morphology composed by three parallel levels of description: semantic, structure and representation. Top-left: analysis of sculptures; top-right: analysis of profiled elements; bottom-left: analysis of the architectural order and bottom-right: analysis of materials.
Research highlights
►Producing and managing multiple representations of buildings according to different analysis needs (Section 3.1). ► Establishing links between the 3D morphology of buildings and the collection of 2D iconographic sources necessary for their study (Section 3.2). ► Analyzing and representing the transformation of buildings in time (Section 3.3).
Introduction
In recent years, the field of architectural survey and representation took advantage from the use of the third dimension in the graphic documentation about cultural heritage. Various tools and emerging technologies [1], [2] have been integrated into approaches for the 3D reconstruction of buildings in order to reproduce the morphological complexity of heritage buildings and to support different analysis requirements [3].
These reconstruction strategies permit both to collect and organize information issue from architectural survey and to produce multiple representations of buildings. To date various reconstruction methods have been developed. Firstly, some approaches are inclined to represent the geometric accuracy of 3D models [4]: they mainly base on the standard methods of automatic meshing starting from 3D laser scanning. Secondly, other approaches are based on descriptions that are specific to particular kinds of analysis [5]: they are characterized by data acquisition and data processing strategies consistent with specific representation goals. Thirdly, other techniques focus on reproducing the visual appearance of the surfaces forming the object [6], by taking into account photometric information. Finally, other approaches concentrate on the simultaneous representation of multiple factors at multiple scales: for this goal, they use different technical procedures in a complementary way [7], [8].
However, beyond three-dimensional data, a large amount of heterogeneous data is collected during the analysis of buildings. Moreover all this data often comes from different branches and relies on different media. Various studies are carried out on heritage buildings for a variety of purposes including analysis of documentary sources, building maintenance and monitoring, formulation of assumptions and cultural diffusion. In addition to architectural survey, the development of qualitative descriptions of buildings is a larger research area. For this reason, today it seems essential to examine how quantitative information (extracted from survey) and qualitative information (produced by interpretation of data acquired during the analysis of documentary sources), can be analyzed and displayed within a unique integrated platform.
Section snippets
Related works
In recent years, the scientific analysis of documentary resources has benefited informatics solutions about how to organize and manage data. Many solutions have been developed in order to improve the management of digital contents [9], other works tend to define a formal structure for describing implicit and explicit concepts and relationships used in cultural heritage documentation [10]. A research consortium [11] also worked on the definition of metadata and paradata related to procedures for
General approach
Organizing the graphical documentation according to the building morphology requires integrating a purely geometric level to a semantic representation one. Actually, the concept of shape encompasses all instances of the object. Instances can be represented in a digital environment, independently from their format, use or size, considering that their geometrical nature is characterized by their spatial extension [19]. Architectural objects have a shape (spatial extension), they can be described
Semantics, temporal dimension and spatial referencing as complementary features
In the previous paragraph we presented the main principles of our platform: the semantic description of the building morphology, the spatio-temporal analysis of its transformations and the spatial referencing of iconographic sources. These three aspects are logically related and can be joined in a complementary way in order to develop new approaches for documenting and studying architectural heritage. We have explored two possible intersections:
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Intersection between morphological description of
Informatics implementation
Our platform, called Nubes [28], consists currently of four tools:
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Archivium, a database for storing 3D representations.
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Tempus, for structuring and displaying temporal changes.
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Imago, for the spatial referencing and semantic annotation of iconographic sources.
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Visum, for the construction of “viewpoints” joining 3D representations, iconographic sources and sets of attributes configured by the user.
These tools are intended primarily for specialists in the field of architectural heritage conservation
Conclusions and future works
In this paper, we presented an integrated platform to manage digital representations of buildings for architectural applications related to the analysis and the documentation of cultural heritage. Various fundamental problems have been explained and various informatics developments have been presented. We are actually working with some specialists in conservation that use our platform in order to organize the 3D representation of artifacts and heterogeneous data coming from analysis of
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