3D Digitisation Guidelines

This guide will help you understand the content of the VIGIE Study 2020/654, which assesses levels of complexity in a wide range of areas associated with the transfer of a tangible 3D object into a digital 3D model. The Study covers a large variety of user scenarios, including the digitisation of highly complex objects in highly complex conditions. The two main distinctions are:
– movable vs. immovable objects
– controlled vs. uncontrolled digitisation environment
It is clear that to digitise e.g. a small artifact in an appropriate digitisation room is very different from digitising an underwater wreck. All the specific conditions for each digitisation project require an analysis and careful planning which copes with the level of complexity and with the unavoidable constraints that affect the digitisation project (e.g. budget constraints, scopes of reuse for the models).

FileData: we intend the set of files that compose the 3D model
MetaData: we intend the descriptive information associated to the cultural heritage object represented in the 3D model
ParaData: we intend the information that describe and capture the digitization process and context applied to create the 3D model, which also grants to perform quality controls on the model itself

In terms of user scenarios and stakeholders, we can identify three basic contexts: museum managers who want to digitise small objects in controlled conditions; public administrations wanting to digitise immovable large objects; cultural organizations wanting to digitise an entire site. 3D digitisation comes with a different degree of complexity, depending on the user scenario and context. This complexity should be assessed in advance as each level of complexity adds required expertise, time, and cost to the digitisation project.

At its simplest an object can be transferred by a single individual into a 3D model using a mobile phone which can be published online, all in a matter of hours. However, the potential of reuse for these basic models, either for research or promotional purposes is very limited. In contrast the highest level of complexities will need coordinated teams of experts, capturing a number of different aspects, using specialist high definition capture systems, in environments which can either change over time or suspend any form of digitisation for any given period. This implies higher investments but offers a result that is truly reusable by different communities of stakeholders (researchers, architects, engineers, creative industry, educators, general public…) and that grants a long term preservation of the 3D model.

Regardless of how easy or complex a 3D digitisation project might be, it is of high importance to always strive for the highest level of quality of 3D digitisation in the cultural heritage sector, in order to produce a result which is not limited to geometry and textures, but which embeds and recovers the memory of an object. This includes the interconnected stories, and knowledge that are associated with a cultural object. For example the origins of the materials may tell another story in the life of the object. Additional knowledge, therefore, needs to be recorded in Paradata and Metadata associated with the file Data generated in the digitisation project.

Every object is unique and carries a significant value in the story of humankind. 3D digitisation is a valuable tool in recording an object’s memory for posterity. It is important to capture this correctly and as thoroughly as possible to avoid losing the narrative for the benefit of future generations. To meet the needs of the maximum number of end users, it is highly recommended to digitise at the highest quality available and to record as much data (FileData, MetaData, ParaData) as possible. This will increase the usefulness of your efforts and help preserve the memory of your objects.

The VIGIE Study helps you assess and measure the complexity of your project. Some of the complexity metrics outlined in the Study, and the Steps below, will be obvious to you, others may not be. By understanding the complexity you will be better placed to effectively record the full story of your object, both visually in 3D and with the associated data that gives meaning to your digitisation. Without having a full understanding of the complexity involved with your project, you are likely to discover that your 3D models are not fit for purpose and only serve as a visual reference, at best. A prior understanding of complexity also allows you to make informed decisions about what you may, or may not, be able to do within the scope of the project or re-assess the scale of project e.g. quality vs. quantity.

• Ask, why are you scanning? Who is for (output quality)? How will it be used?
• What are you scanning? How many objects? Are they moveable? Are they indoors / outdoors?
• Can you achieve the project internally, or will you require (e.g. expertise not available in-house, or more cost effective) to use external contractors to produce the digitisation?
• Devise a Project Plan.
• Identify all of the requirements necessary for digitisation which may create a barrier to digitisation. e.g. site access, contracts and legal issues, permits etc.
• Conduct a site visit and object assessment.
• Identify a suitable recording method (digitisation equipment) based on what you are scanning and the requirements (quality) for your output.
• In advance, record any details that may create issues and need a remedy. e.g. reflective surfaces, accessibility issues, lighting problems.
• For outdoor objects, plan for environmental changes. e.g. delays or deviations in quality/consistency due to varying conditions.
• Consider the data storage required during digital acquisition and post processing requirements.
• Assess file formats and 3D platforms for publication. Ensure you can store the highest quality available on demand for specialists and have flexible format options for general accessibility / viewing.
• Record detailed paradata during the digital acquisition. Equipment may automatically record some paradata but ensure all the other details (e.g. how, who, conditions) of the digitisation process are recorded.
• Record metadata (the descriptive details of the object itself)
• Assess/validate quality – accuracy and resolution of the output in comparison to the project objectives and the intended use.
• Publish your 3D models, metadata and paradata, also taking into account long term archiving strategy
• Disseminate your project to your target stakeholders.

3D digital objects provide more detail, scale and possibilities for in depth interaction than 2D equivalents. This has various impacts, but most of all 3D experiences can provide more immersive ways of exploring cultural heritage content and engaging visits to cultural sites and institutions.

3D objects are useful resources in learning, education and research, in exploring and preserving heritage sites and monuments and in helping reconstruct heritage. 3D models of museum objects, monuments and sites can be reused in Virtual Reality (VR) and Mixed or Extended Reality (MR, XR) experiences, such as virtual tours or virtual training, and in Augmented Reality (AR) applications for education, tourism and city/museum tours. In addition, from the 3D models it is possible to produce printed models, useful for children engagement, artifact handling and teaching, sensory and accessibility experiences to be offered to impaired visitors, and other creative reuses leveraging 3D printing.

Last but not least, another important domain that highly benefits from 3D digitisation is research. This is especially relevant for heritage sites, monuments and objects which are deemed at risk. 3D digitisation allows for detailed analysis and monitoring of monuments and sites and of cultural heritage objects, either indoor, outdoor or underwater, including measuring, observing fine details not readily visible to the naked eye or in simple 2D recording, comparing the details of related objects of similar type, monitoring the impact of specific factors on objects over time (such as wind, pollution, erosion, visitor traffic).
Finally, the 3D scanning of objects is crucial in the fight against illicit trafficking of cultural goods: the presence of 3D models in the databases of stolen works used by the police and customs forces allows for a gain in speed and efficiency in the in situ identification of these objects.

The various stakeholders and categories of re-users for the 3D models may have different needs and requirements; yet the very starting point to enable use and reuse of the 3D models is discoverability. Next to publishing and disseminating the 3D collection on Institution’s website, pan-european platforms like Europeana, the Data Space for Cultural Heritage, the upcoming European Collaborative Cloud for Cultural Heritage, and e-infrastructures and repositories dedicated to the various research communities offer opportunities to share and link datasets about 3D cultural heritage to a wider audience.

3D objects can generate a complex scenario about the rights to be attached to the model once it is published. In general terms, in order to support the largest use and reuse of the 3D models, it is recommended that an open access approach is considered. Especially when the 3D model is a faithful representation of a real-world object, it is not expected that additional rights are imposed (which means that if the object is in the Public Domain, its digital representation be it in 2D or 3D should be as well Public Domain). Yet, there may be constraints which prevent this approach to be taken, such as national legislations, contractual agreements, or the methods used to create the model. For example, many collection holders do not have expertise or equipment to perform 3D digitisation in-house and thus the task is often outsourced to service providers that are contracted to perform the scanning and generate the models. Also, depending on the methods employed to make the 3D object, the object can be the result of the work of various people, and, in case a creative method is used, the artist’s intellectual property. This may also mean that the same physical object may have different 3D reproductions with different features, which may bear different rights (for example, a faithful digitisation of archaeological ruins vs. their virtual reconstruction creatively recolored). It is therefore of the utmost importance to clear the rights in the contract or service agreement with the service provider, in order to allow the content holder to retain the maximum freedom in sharing the model with a reuse license.