3D Restitution Research Articles

Naming, relocating and dating the woods of Notre-Dame “forest”, first results based on collated data and archaeological surveys of the remains

The tragic fire of Notre-Dame Cathedral in Paris on April 15th 2019 has provided researchers with a wide variety of materials to study. The condition of the framework remains does not allow any reuse, which creates an unprecedented opportunity to study the charred pieces of the frame: about 10,000 for the highest estimates. But upstream from the wooden items study, an inventory is required to establish methods that are consistent with the potential of the charred remains of the cathedral's framework. The purpose of this article is therefore to present the problems raised, the methods applied, the potential of the remains of the n-dame's frame - so called the "forest" - and the first results.

Erratum to ‘Naming, relocating and dating the woods of Notre-Dame “forest”, first results based on collated data and archaeological surveys of the remains’ [Journal of Cultural Heritage Volume 56C (July-August 2022) 75-84

• A survey in terms of meaning and witness: identify, give a name, and even replace wooden pieces in the original Notre-Dame de Paris's framework using digital resources. • 3D restitution is helpful to create precise wood volume estimations. • First results of dendrochronology enable the phasing of the different parts of the Notre-Dame's frameworks. • The relocated remains dating will confirm or overturn archaeological hypothesis and allow wood resources studies. The tragic fire of Notre-Dame Cathedral in Paris on April 15 th 2019 has provided researchers with a wide variety of materials to study. The condition of the framework remains does not allow any reuse, which creates an unprecedented opportunity to study the charred pieces of the frame: about 10,000 for the highest estimates. But upstream from the wooden items study, an inventory is required to establish methods that are consistent with the potential of the charred remains of the cathedral's framework. The purpose of this article is therefore to present the problems raised, the methods applied, the potential of the remains of the n-dame's frame - so called the "forest" - and the first results.

EXPERIENCE AND ATMOSPHERE OF THE BUILT HERITAGE IN DIGITAL ENVIRONMENT

Abstract. The digital documentation of heritage places produces accurate 3D restitution of their geometry in a virtual environment and can be related to multiple semantic layers to archive, represent, preserve and transmit the knowledge gathered along their lifecycle. The combination of high-density point clouds with other sources of information advises virtual reconstitutions of historical states of a place’s physical realm. The cultural significance of the built heritage lies in the values associated with its tangible and intangible dimensions. Apart from aspects of values related to historical sites’ physical attributes, 3D models can support the representation of intangible elements influencing visitors’ perception of their Genius Loci and supporting new interpretations about their cultural significance. In this framework, 3D animation, rendering, and simulation technologies allow recreating aspects of a place’s atmosphere, like the simulation of lighting conditions and the user’s immersive experience of a heritage site into a virtual environment. This paper focuses on the light perception recreated in a funeral chapel of the Theban Tomb environment by considering the strong spiritual dimension in the conception of funeral sites in ancient Egypt during the New Kingdom period (1550–1069 BC). We investigate the potential of 3D simulation and animation technologies to represent hypotheses about original lighting conditions in such sites. The proposed research is based on the case study of Sennefer’s tomb chapel, also referred to as TT96A, located on the western bank of the Nile, opposite modern Luxor.

Les technologies de restitution 3D au service de la connaissance des plafonds peints médiévaux

La modélisation 3D présente un véritable intérêt dans la connaissance et la diffusion des savoirs sur les plafonds peints médiévaux. Indissociables de l’architecture, mais aussi porteurs d’un contenu artistique et social riche encore méconnu, leur étude s’avère complexe pour plusieurs raisons : difficulté d’accès aux sites, structures aux multiples volumes, décor peint souvent détérioré, manque de documentation historique, etc. Les travaux de recherche de ces trente dernières années ont démontré l’importance de l’organisation générale du décor peint. Pour en étudier sa symbolique le recours à l’imagerie numérique sous la forme de modèle 3D permettrait de pallier nombre de ces contraintes. L’association internationale de Recherches sur les charpentes et plafonds peints médiévaux (RCPPM) explore actuellement les pistes pour l’application de la modélisation 3D à ces objets d’étude.

RECONSTRUCTION OF URBAN SITES FROM PHOTOS

Abstract. This paper reports the results of an experiment that aims at the virtual reconstruction of a urban site that has been partially reshaped during the 20th century; the reconstruction process is based on period photos. The chosen case study is the eldest harbour of Palermo, named ‘Cala’; the site was bombed during World War II and new buildings took the place of the ruined ones. Two period photos, taken from an aircraft, document the buildings that were destroyed by bombs. The 3D restitution process used the ‘inverse’ projection from period photos (2D) to the virtual space (3D) ; the first step was therefore addressed to the calculation of the inner parameters (focal length, principal point coordinates) and of the cameras’ pose, i.e. their position and orientation. The data needed for these calculations were extracted from the 3D laser scanning survey of those buildings that appear in photos and that are still on site. The calculation of inner parameters and poses has been computed with a motion tracking commercial package. The second part of the paper focuses a process for the fruition of virtual reconstructions, based on the alignment of real panoramic images, generated by photos taken on site, and of virtual panoramic images, extracted from the 3D reconstruction model; the proposed method uses SfM photogrammetric tools.

Mapeamento dos compartimentos do relevo do município de Estrela do Norte-SP e adjacências – a partir de técnicas de visualização estereoscópica digital

O mapa geomorfológico é considerado um importante instrumento na pesquisa da paisagem, pois auxilia na análise dos processos relacionados ao relevo. Desse modo, o presente trabalho teve como objetivo, elaborar o mapeamento dos compartimentos de relevo do município de Estrela do Norte-SP e adjacências, localizado no Extremo Oeste do Estado de São Paulo, utilizando técnicas de estereoscopia digital com restituição – 3D, através das imagens ALOS/PRISM, vinculados a trabalhos de campo identificando os solos, as formações geológicas e as dinâmicas atuais do uso e ocupação dos solos.https://doi.org/10.14195/0871-1623_35_9

3D RECONSTRUCTION OF AN UNDERWATER ARCHAELOGICAL SITE: COMPARISON BETWEEN LOW COST CAMERAS

Abstract. The 3D reconstruction with a metric content of a submerged area, where objects and structures of archaeological interest are found, could play an important role in the research and study activities and even in the digitization of the cultural heritage. The reconstruction of 3D object, of interest for archaeologists, constitutes a starting point in the classification and description of object in digital format and for successive fruition by user after delivering through several media. The starting point is a metric evaluation of the site obtained with photogrammetric surveying and appropriate 3D restitution. The authors have been applying the underwater photogrammetric technique since several years using underwater digital cameras and, in this paper, digital low cost cameras (off-the-shelf). Results of tests made on submerged objects with three cameras are presented: © Canon Power Shot G12, © Intova Sport HD e © GoPro HERO 2. The experimentation had the goal to evaluate the precision in self-calibration procedures, essential for multimedia underwater photogrammetry, and to analyze the quality of 3D restitution. Precisions obtained in the calibration and orientation procedures was assessed by using three cameras, and an homogeneous set control points. Data were processed with © Agisoft Photoscan. Successively, 3D models were created and the comparison of the models derived from the use of different cameras was performed. Different potentialities of the used cameras are reported in the discussion section. The 3D restitution of objects and structures was integrated with sea bottom floor morphology in order to achieve a comprehensive description of the site. A possible methodology of survey and representation of submerged objects is therefore illustrated, considering an automatic and a semi-automatic approach.

Photogrammetry Based Study of Ceramics Fragments

Reconstitution of whole ceramics from fragments is a true priesthood for ceramographers. This activity remains mainly handled by manual sketching and can be very time consuming. However, more and more tools and workflows provide digital solutions, based on 3D technologies, to assist such tasks. In this paper, we present an application of photogrammetry on ceramic fragments from two excavation sites located in Brittany, France. This study was required by two ceramics specialists and conducted in CReAAH, a French research center in archaeology, archaeosciences and history. The 3D restitution by photogrammetry of these different fragments allowed reconstructions of the original shapes of the potteries or at least to get to as close as possible. We furthermore used the resulting 3D models of the ceramics to compute various metrics required by the ceramographers. In collaboration with IRISA, a French research center in computer science, we designed and generated a presentation support using a 3D printer. This work is based on affordable tools and illustrates how 3D technologies can be quite easily integrated in archaeology process with limited financial resources, to obtain useful results for the study and analysis of such artefacts.

3D restitution, restoration and prototyping of a medieval damaged skull

PurposeThe purpose of this paper is to describe the method of virtually and physically reconstructing the missing part of a badly damaged medieval skull by means of reverse engineering, computer‐aided design (CAD) and rapid prototyping (RP) techniques.Design/methodology/approachLaser scanning data were used to create the 3D model of the damaged skull. Starting from this digital model, a virtual reconstruction of the missing part of the skull, based on the ideal symmetry with respect to the mid‐sagittal plane, was achieved in a CAD environment. Finally, the custom‐designed model was directly fabricated by means of the RP process.FindingsThe result shows that the designed missing part of the skull fits very well with the existing skeletal remains. The final physical assembly of the prototyped element on the damaged skull was tested, restoring it to its whole original shape.Research limitations/implicationsThe entire process was time‐consuming and may be applied just to the most representative skeletal remains.Practical implicationsThe method allows accurate fabrication of the missing part of the skull to be joined with the original skeletal remains. The advantage of using this technique is that the joining operation can be carried out without any need of supplementary connecting material, such as glue or plaster, to fix together the two parts.Originality/valueThe reversible and non‐invasive method improves the restoration process, reduces the risk of damage to the skeletal structure and allows reversion to the original repair as it was before.

L'apport de la stéréophotogrammétrie à l'étude de la dégradation des pierres monumentales (Contribution of stereophotogrammetry to the study of monumental stones weathering)

Stereophotogrammetry is used as a method to quantify and spatialize weathering processes affecting stones monument to compensate for the imprecision of conventional methods. Tests are executed on alveolar erosion of gneiss stones of the Manglieu church (Puy-de-Dôme). Advantages and limits of the field work, level of the data precision and capacity of the 3D restitution are evaluated. Application fields of the method are also discussed as well as the potential technical alternatives.

Describing the Geometry of 3D Fracture Systems by Correcting for Linear Sampling Bias

Analyzing the geometric bias inherent to linear sampling of natural fracture systems is a prerequisite to any attempt of structural modeling. In this paper, the basic parameters of 1D-sampled fracture sets, i.e. orientation, density, and size, are interpreted in terms of geometric probabilities. Weighting factors are derived which allow the 3D restitution of a moderately variable fracture network from a single borehole. The proposed method is applied to well core data from a granitic rock mass, and the efficiency of the proposed corrections is illustrated through random disc simulations tested by virtual scanlines analogous to the real borehole. This approach aims to reduce the prospecting effort in exploration, and to criticize assumption of structural homogeneity by rigorously comparing fracture populations collected from nonparallel boreholes. Then a parametric study of fracture size is performed and a range of mean size leading to fully connected networks is identified.