Evaluating the development of open 3D city models: a multidimensional assessment

Abstract. Adopting 3D City Index, a comprehensive 3D data scoring framework encompassing four categories—data portals, model descriptions, thematic content, and semantic information, we assess and benchmark currently available 3D city models made accessible openly by governments worldwide. The 2025 update, including 47 datasets, reveals both the current situation and advancements in the open 3D data landscape since the previous benchmark 3 years ago. The heterogeneous landscape continues, with European cities demonstrating sustained progress, such as the datasets of Helsinki and Espoo. Japan as a country, performs well in the large-scale availability of 3D geoinformation. The trend analysis between 2022 and 2025 highlights measurable progress in the development of open 3D city models. Among the 28 datasets assessed in both years, 11 models show improvement, with an average increase of 2.5 points. While in general there is an improvement, many aspects declined, such as data portals and semantic richness. Further, the analysis implies an emerging trend toward large-scale harmonised initiatives at the state or national level, such as the PLATEAU project in Japan and Digital Twin Victoria in Australia. Such efforts indicate promise for standardised modelling, interoperability, and collaboration between governments, companies and research institutions. Understanding the current status and development of 3D city models, this work aims to inform improvements of 3D geoinformation and support broader adoption of 3D city models in research and practice.