Digital reconstruction resources as FAIR data. Practical use of application Ontology for Preservation of Cultural Heritage 3D Models (OntPreHer3D)
Creators: name: Bajena, Igor
Publisher: name: Zenodo
Year: 2024
Subjects: digital 3d reconstruction
ontology
3d models
CIDOC CRM
cultural heritage
architectural 3D models

description: Presentation introducing the OntPreHer3D ontology in the context of the Erasmus+ CoVHer project at the CAA2024 conference in Auckalnd. The ontology itslef and its further development can be followed on GitHub page: https://github.com/igorbajena/OntPreHer3D 
description: CONTEXT

Preservation of 3D models of digital reconstructions requires ensuring access, transparency, interoperability, and reuse of published data. In the era of web 3.0 and linked open data (LOD), it is necessary to use ontologies to make the data machine-readable and to show the relationships between entries. In the cultural heritage sector standardized solution which allows to achieve it is CIDOC CRM. The basic model concerns only general concepts, which may turn out to be insufficient in describing the digital reconstruction. For this reason, official extensions are created to enable more detailed documentation of various aspects. An example in the context of digital reconstructions may be use of CRMinf, CRMgeo and CRMba, which enables the analysis of individual building elements and the relationships between them, as well as in terms of the origin of the presented reconstruction knowledge (Bruseker et al., 2015). Another approach is covered by creation of an application ontologies, which enables the addition of custom classes and properties to capture aspects relevant to a specific of the project. This approach was used in the digital reconstruction project of the New Synagogue in Wroclaw (Kuroczyński et al., 2021) by creating an Ontology for Scientific Documentation of source-based 3D reconstruction of architecture (OntSciDoc3D)[1]. This ontology enables capturing the relations between the reconstruction and used source materials, historical background of the building, also considering the possibility of assigning a hypothesis level (uncertainty) to individual building elements.

Issues related to the documentation of 3D models of digital heritage and the use of these ontological solutions unfortunately require an additional contribution to the creation of an appropriate infrastructure, which many institutions cannot afford. In the face of these challenges, the prototype of a 3D model preservation infrastructure was created in the form of a 3D Repository (https://3d-repository.hs-mainz.de/), an open platform for publishing 3D models of cultural heritage using for documentation the CIDOC CRM base model with extension of the OntSciDoc3D application ontology mentioned above. A WissKI virtual research environment based on the Drupal content management system was used to build it. The created service was intended to provide a simple metadata form which aimed to enable linking of selected entities to external data repositories and authority files (e.g. ORCID, Getty AAT, or Wikidata), and to provide visualization of the 3D model in a web-based viewer. However, survey on user requirements showed the need for a more universal documentation scheme that does not focus only on digital reconstructions. At the same time, respondents pointed the need of possibility to document information specific to fields, such as archaeology or art history. In addition, the issue was noted regards model publication process and highlighting differences between the original model in native format, the exported file intended for visualization in the repository and the processed file by the system, which is displayed in the viewer. 

MAIN ARGUMENT

Digital reconstruction consists of two aspects: the historical study of an object and the use of digital modelling and visualization methods to present the obtained results in the form of a virtual simulation of the object's past. Mentioned ontological solutions focuses on documenting the historical research, but not used methods for obtaining visual results. To fully understand the process, it is also necessary to present used methodology form technical point of view, what can influence perception or level of accuracy of the model. The CRM family has an extension CRMdig focusing on capturing the process of the provenance of digital data, but it is limited to the broad process of digitization and automated data acquisition, without addressing the distinction of modelling methods related to digital reconstruction. It also does not sufficiently cover the topic related to the preservation of 3D models. Analyzing the life cycle of a digital resource, a key moment is its publication, as this enables entering the phases of archiving, acquisition and reuse.  A properly conducted documentation of a published digital 3D reconstruction should include topics related to the goals of publishing, the methods used for digital modelling and its geometric representation, methods of visualizing of the presented results, as well as transparency in terms of historical research, used sources, evaluation of the hypothesis level and the scientific value of the model (Bajena and Kuroczyński, 2023).

In view of this premise, an Ontology for Preservation of Cultural Heritage 3D Models (OntPreHer3D)[2] was developed to capture in detail the process of model publication (M5 Web-publication) and the creation of new repository entries (M6 Web-based entry) together with the distinction between the 3D file (M1 Digital Model) and its visualisation (M7 Web-visualisation) and using CRMdig and OntSciDoc3D to capture other aspects of the process. The 3D model publication process expressed by OntPreHer3D is shown in Fig.1 The ontology contains 35 classes from the CRM base model, 5 classes from CRMdig, 9 classes from OntSciDoc3D and introduces 16 new classes related to publication process including model characteristics (M15 3D Geometry, M16 3D Material), relationships between 3D models (M2 Versioning, M3 Variation, M4 Division) or classification of cultural heritage objects based od its size/scale based on the Getty AAT (M11 Single Built Work, M12 Furrnishing and Equipment, M13 Compnent, M10 Area).

APPLICATIONS

The current level of work focuses only on the publication process, but further development is planned towards capturing the methodology of work on the 3D model, historical research on the object and the presentation of research hypotheses, including the use of further extensions of the CIDOC CRM family. It is also planned to verify the practical use of the proposed ontology as part of the construction of a new WissKI repository for the European CoVHer (Computer-based Visualisation of Architectural Cultural Heritage) project[3], where the use of new documentation and publication methods for digital reconstruction models in the higher education sector will be investigated. The presented approach to the documentation of 3D models based on OntPreHer3D can allow easier access to 3D data, a better understanding of the methods used from a technological point of view and contribute to an increase in the reuse of the 3D data the broad field of cultural digital heritage, not just limited to hypothetical digital reconstructions.

 

 

BIBLIOGRAPHY

Bajena, I., Kuroczyński, P. (2023). Metadata for 3D Digital Heritage Models. In the Search of a Common Ground. In: Münster, S., Pattee, A., Kröber, C., Niebling, F. (eds) Research and Education in Urban History in the Age of Digital Libraries. UHDL 2023. Communications in Computer and Information Science, vol 1853. Springer, Cham. https://doi.org/10.1007/978-3-031-38871-2_4

Kuroczyński, P., Bajena, I., Große, P., Jara, K., Wnęk, K. (2021). Digital Reconstruction of the New Synagogue in Breslau: New Approaches to Object-Oriented Research. In: Niebling, F., Münster, S., Messemer, H. (eds) Research and Education in Urban History in the Age of Digital Libraries. UHDL 2019. Communications in Computer and Information Science, vol 1501. Springer, Cham. https://doi.org/10.1007/978-3-030-93186-5_2 

Bruseker, G., Guillem, A., Carboni, N. (2015). Semantically documenting virtual reconstruction: building a path to knowledge provenance. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2, 33-40. https://doi.org/10.5194/isprsannals-II-5-W3-33-2015  






[1] OntSciDoc3D, https://www.ontscidoc3d.hs-mainz.de/ontology/




[2] OntPreHer3D, https://www.ontscidoc3d.hs-mainz.de/OntPreHer3D/




[3] CoVHer website, https://covher.eu/