ROLE OF 3D CITY MODEL DATA AS OPEN DIGITAL COMMONS: A CASE STUDY OF OPENNESS IN JAPAN'S DIGITAL TWIN "PROJECT PLATEAU"

Abstract. This study aims to clarify the development and utilization of highly accurate and open 3D city models (3DCMs), which began in Japan in 2020. The background of the project is explained based on a review of past efforts in Japan for making geospatial information accessible, the flow of data standardization around CityGML, and the introduction of Free and Open Source Software for Geo-spatial (FOSS4G) tools for data management and visualization. Two aspects of the analysis are reported: quantitative geospatial analysis of LOD1 building data and qualitative evaluation of 40 use cases using these data. The results indicate that approximately 18 million building data points covering 150 cities in Japan have been converted to open data in formats such as CityGML with high accuracy, complementing OpenStreetMap (OSM) data in urban areas. In addition, a total of 40 use cases for these data are demonstrated in new fields, such as urban planning, citizen participation, and even entertainment, with a few of these tools becoming open-source software. Through this project, data related to 3DCMs, which have not necessarily been produced in a unified format or specification in Japan, can now be easily handled as CityGML through a one-stop viewer, and the data are expected to be enhanced, and new geo-services using 3DCMs will be provided under the concept of openness, regardless of the city scale.