David Lo Buglio

Critical Review of 3d Digitization Methods and Techniques Applied to the Field of Architectural Heritage: Methodological and Cognitive Issues

This article concentrates on the epistemological aspects of architectural survey. It offers a critical observationof the technologies used in the field of 3D digitization. More specifically, the study evaluates the way in whichthe tools and methods used for the acquisition and representation of the data do or do not contribute to theenhancement of architectural knowledge. To understand the relationships between technology and knowledgetransfer, we will carry out an observation based on a series of case studies. This is intended to highlight a dual issueof a cognitive nature: the first, perceptual, refers to the comprehension of the object and the second, descriptive,refers to the intelligibility of the 3D information model. This reflexive approach is justified by the fact that the maintechnological advances rarely compensate the methodological deficiencies encountered. Finally, this article offersperspectives for the in-depth study of all the cognitive mechanisms involved in the architectural survey.

Geometry vs Semantics: Open Issues on 3D Reconstruction of Architectural Elements

Three-dimensional representation is becoming an effective support for the documentation of the state of conservation of heritage artefacts, for the study of its transformations and for cultural diffusion. 3D digitization technologies now offer effective means to observe and analyze historic buildings with more accuracy, completeness and timeliness. Nevertheless, this produces a real problem of information overload. The growing mass of un-interpreted data make emerge a need for innovative methodologies assisting data processing, sorting and analysis by researchers who want to use it for advancing the knowledge of cultural heritage. Exploring the informational value of these new representation systems allows introducing new approaches to the analysis of artefacts so distant in space but so close in features typologies, styles, compositional rules, etc.. This chapter presents some research avenues for defining a geometric/semantic description model of architectural elements in order to integrate the informative value of 3D digitization in intelligible representations.

What Do Thirty-One Columns Say about a “Theoretical” Thirty-Second?

Over the past three decades, the introduction of digital technologies in the field of architectural documentation has profoundly changed tools and acquisition techniques. Most of the developments concern metrical and colorimetric characteristics of the objects studied. These developments, surrounding the practice of architectural survey, tend to respond primarily to the requirements of completeness. In this context, it seems necessary to assess the impact of these instruments on the cognitive value of architectural representation. With a strong technological presence, the study of the built heritage is facing a problem of “information overload.” Indeed, this strong technological presence fails to strengthen representation in its role as a vehicle of knowledge. Confronted with the intelligibility deficit, this article proposes an original approach for reading morphological features of an artifact by using a bottom-up approach: the meaning of elements (i.e., their semantic layouts) come from a statistical analysis of the major shape discontinuities of a collection of instances. The idea is to rely on data accumulation to render apparent high-level semantic structures from the comparative analysis of common low-level geometric features. The principles introduced are illustrated by the study of 31 columns of the cloister of the abbey of Saint-Michel-de-Cuxa. To summarize, the first objective is to understand how digital technologies can help us in the analysis of artistic and technical production of Romanesque columns. The second objective is to automatically identify the common semantic articulations of the entire collection to build a reference model for the future assessment of each artifact.

Morphological Analysis of Shape Semantics from Curvature-based Signatures

Over the past few years, advancements in the field of 3D digitizing has increased the fidelity of geometric models. So far and despite of this acuity enhancement, a gap remains between the growth of collected data and its uses as vehicle of knowledge. New challenges have emerged to handle massive content of a 3D footprint. Considering those un-interpreted data as starting point for further investigations, the hypothesis is to rely on a “low-level” analysis of geometric features aiming to enrich informative and scientific value of “high-level” semantic studies. This article describes an approach using discrete curvature assets to link morphological identification and semantic characterization. The mean curvature has been parametrized to highlight it use as an eloquent shape description. At this point, a comparative analysis within an architectural collection composed of similar entities would be led according to the remoteness degree compared to an average geometric reference model. The introduced principle explores the construction of curvature-based signatures so as to reassess the conceptual articulations of 31 Romanesque columns from the cloister of the abbey of Saint-Michel de Cuxa.