A Study on the Development and Future Directions of the National Digital Twin: A Case Study of Korea

The rapid advancement of digital twin technologies has increased the importance of establishing interoperable geospatial information standards for national-scale Digital Twin implementation. The Republic of Korea has developed the National Digital Twin (NDT) standard framework based primarily on OGC CityGML 3.0. This study presents a case-study-based analysis of the development and application of the Korean NDT standards, focusing on how a geospatial standard framework can be structured and extended to support a national-scale Digital Twin. A comparative review of international initiatives indicates that existing approaches generally develop CityGML-based 3D city models as geospatial foundations and subsequently extend them toward Digital Twin applications, whereas the Korean NDT establishes a common reference framework and geospatial data models as a standardized foundation for national-scale Digital Twin implementation. The analysis examines the phased development process, the hierarchical relationship among the reference framework, core data model, and application data models, and the organization of multiple spatial domains, including Building, Transportation, Terrain, Indoor Space, and Underground. The applicability of the NDT standards was further examined through pilot dataset implementation and validation from schema, semantic, geometric, and topological perspectives. The analysis also identifies current limitations, including restricted data openness, limited software support for CityGML 3.0, and the need for further mechanisms to integrate dynamic information. Based on these findings, this study discusses future directions for NDT standardization, including model management, standardized data production and validation, dynamic information integration, and technical implementation guidance. The Korean experience provides a case for understanding both the potential and practical challenges of applying CityGML 3.0-based geospatial standards to national-scale Digital Twin initiatives.