In recent years, 3D city models have become increasingly important for urban planning, citizen engagement, and research, driven by rapid advancements in technology and infrastructure. These models allow for a more detailed and accurate representation of urban spaces, which enables city planners, researchers, and citizens to visualize changes and make more informed decisions. Many cities and countries around the world have adopted these models to address a wide variety of urban challenges, enhance public participation, and aid decision-making processes at multiple levels of governance.

Particularly in Japan, the Ministry of Land, Infrastructure, Transport, and Tourism, through its Project PLATEAU initiative, has been at the forefront of promoting the use of open 3D city models and 3D point cloud data. These open data initiatives have allowed cities to make their urban landscapes more transparent and accessible to a broader audience, including citizens, planners, and developers. As of February 2023, more than 100 cities across Japan are actively developing and releasing their Digital Twin data in CityGML format, a widely used standard for representing 3D city models. This initiative has gained international recognition and is highlighted in the research findings by Binyu et al. Furthermore, it has been featured in the 3D City Index benchmarking report, which shows that seven out of the 40 evaluated cities (18%) are Japanese, demonstrating Japan's leadership in this space.

This report delves into the ongoing collaboration between Japan’s Digital Twin initiatives and the global OpenStreetMap community. The open digital twin data in Japan, adhering to the open database license ODbL, has been integrated with OpenStreetMap, allowing for the combination of detailed 3D data with one of the most widely used open-source mapping platforms. Specialized tools and converters have been developed to facilitate this integration, which began experimental trials in 2022, in collaboration with both national and international communities. The dissemination of results and the challenges faced throughout this process are expected to encourage the global adoption and utilization of 3D city model data.

In this talk, we will summarize the current status of merging PLATEAU 3D building data that has been imported into OpenStreetMap, along with the challenges and possibilities encountered. We will also share our insights with mappers worldwide, highlighting the fact that many countries, not just Japan, are adopting CityGML for their urban Digital Twin data development.