## 4 Implications for the Design of 3D Data Infrastructures  
A multitude of implications has been already collected and compiled for the design of 3D data infrastructures [68]. One main differentiation lies in the purpose of 3D data infrastructure, such as data repositories to store and preserve data, viewer infrastructures  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**International (e.g., EU Level)** & **Multinational** & **Germany** \\ \hline \hline
**Data Infrastructures** & The Digital Europe Data Space [15] for Cultural Heritage, maintained by European, provides data repositories and aggregation; for instance, for heritage data. The European Cloud for Cultural Heritage (ECCCH) [68] will develop a toolset for cultural institutions. The European Open Science Cloud (EOSC) [69] provides a set of core services to store and share research data. Various VRES deal with 3D data; for example, E-RIHS [70] for heritage science and ARIADNE+ for archaeological data. & Several national 3D infrastructure consortia are already formed; for example, in Sweden, [71] UK [72], Ireland [73] or France [74], or the Netherlands [75]. & Baureka.online [78] provides a portal to store and share research data, particularly for historical architectural research. The FID BAUdigital [79] provides information services for Civil Engineering, Architecture, and Urbanism. The DFG 3D Viewer is a multi-source repository. \\ \hline
**Education** & The KIC CCTS AP 1 and 2 are dedicated to aligning curricula for graduate and postgraduate education in Europe.DARIAH Teach [80] and the TMO Academies [81] provide OER material for learning 3D-related skills. & The Computer-based Visualization of Architectural Cultural Heritage (CoVHer) [82] ERASMUS+ project strives to define applicative/practical guidelines and operational methodologies for 3D models of artefacts that no longer exist or have never been built. & The FUT Interregional Partnership for Virtual and Smart Cultural Tourism [91] is a multi-regional community and project hub around digital heritage. \\ \hline
**Community** & Time Machine [85], the European Network Association [18], and the ICOMOS/ISPRS CIPA [86] are domain-independent large networks of heritage professionals. Networks such as CAA [87] for archaeology or ICARUS [88] for archival studies are domain-specific platforms. The 4 CH Competence Centre [89] is developing a concept for a Europe-wide support structure for 3D data [90]. & The EU Interregional Partnership for Virtual and Smart Cultural Tourism [91] is a multi-regional community and project hub around digital heritage. \\ \hline  
for publishing and viewing content, and feature-rich virtual research environments (VREs) that provide tool collections and working environments with many infrastructures serving multiple roles. The investigations identified several current challenges, including:  
* **Public repositories contain comparatively few 3D model data to date:** Although numerous infrastructures for 3D models on a national level are currently in formation, the expansion of the publicly hosted model pool still represents a significant challenge. Another issue for preservation is finding repositories capable of accepting the exceptionally large datasets resulting from very high-quality digitization of large objects. Many models are still not publicly accessible due to being stored in local data repositories [2]. Although Sketchfab is not a preservation repository but a private viewer platform, it still contains the majority of publicly accessible models. Due to the characteristics of platform businesses toward winner-take-all dynamics [108], there is a tendency for one platform to dominate the market. This could be addressed by concurring platforms reaching a significant size; for instance, by content aggregation or serving specific purposes, such as privacy and long-term preservation. There are also market gaps visible as opportunities to store (very) large high-quality 3D datasets are missing.