EUreka3D

There are many challenges associated with the ingestion, processing, aggregation and delivery of 3D content. These challenges stem from the nature of 3D content, current hardware limitations and the quality target set by the VIGIE study, followed in EUreka3D, as it promotes guidelines to ensure the highest level of quality and the best possible outcome. The current capabilities of consumer computers and networks impose limitations and challenges in the design of the EUreka3D platform. Quite often, the processing of 3D data online is done on the client side, so the actual device users use plays a key role. This must be considered when designing 3D experiences, which are affected by network limitations, computer memory or processing capacity.

The 3D industry has greatly evolved over the years but still lacks the standardisation level that 2D content has. This lack of standards for the use of 3D data makes it a challenge to decide on a universal 3D format. There is no complete alignment between the 3D software to process 3D data and the software to visualise or deliver 3D experiences to users. Herein, some content providers may use a format for the archival of 3D data, but this may not be the best choice for visualisation or delivery to end users. For example, OBJ is a widely known format, commonly accepted by 3D software and 3D visualisation libraries. Still, it is less space-efficient for data, making it a poor choice if the data to be sent over a network are too large. Such cases can benefit from a binary format such as PLY. The Nexus multi-resolution format, created by CNR, delivers 3D data more efficiently over the network; however, it is not supported by common software, and current technical challenges make it unsuitable for 3D CAD data. Some algorithms and 3D formats focus on compression ratio, while others focus on performance. It is usually a trade-off: compression makes more efficient use of space (benefiting, for example, the storage or transfer of a file) but increases processing effort (both for compressing and decompressing the data). These are not intrinsic problems for 3D, as 2D content also suffers from them, but they are more prominent in 3D because 3D is more complex in nature, and 3D content requires extensively larger amounts of space than 2D content, which affects its storage, processing and transfer over a network.

Another difference with the 2D industry is that the 2D industry has already solved basic aspects of 2D content visualisation. Even if new 2D formats emerge to solve new problems or improve certain aspects, the use of 2D content is basically transparent to developers, who for the most part do not have to deal with the burden of implementing or configuring 2D visualisation tools. For example, using an image on a Web page is a simple process that barely requires any effort from the developer, as the Web browser is already prepared to handle the situation in a globally expected way. However, the use of 3D content may still require developers to address some fundamental questions and make decisions on aspects such as the support library to be used, the data format to be accepted for efficient delivery and processing, and so on.

The Cultural Heritage sector can very much benefit from recent trends in IT, such as the use of cloud technology, and this is part of the way forward in the necessary digital transformation of the discipline. This is clearly evident from the storage needs of cultural heritage objects, especially those implementing the #MemoryTwins idea (as opposed to Digital Twins), which not only store the geometric structure of 3D models but all the analyses that tell the story of an object.

Metadata (information about a Cultural Heritage object) and paradata (information about the digitisation process of a Cultural Heritage object) are also necessary requirements of digital objects in Cultural Heritage. 3D metadata information has been studied for a long time, and many of the challenges involved have been minimised with the help of the Europeana Data Model (EDM), which provides a common framework for the understanding of systems that exchange Cultural Heritage metadata. However, paradata information processing is a necessary yet not widespread practice amongst 3D content providers and is not currently addressed by EDM. Delivering the paradata information associated with some data provides key insights into how the digitisation process was carried out to obtain the data. Although there are different initiatives and efforts focused on the description of paradata, Cultural Heritage lacks a formal data model to express them, and this is one of the future enhancements planned for the Europeana Data Model.