Development of an Urban Digital Twin Based on Geospatial Data: A Case Study of Busan, South Korea

South Korea has been advancing the National Digital Twin Land initiative; however, many existing urban digital twin projects have relied on non-standard, visualization-oriented datasets, thereby encountering persistent difficulties in securing interoperability and reusability. In particular, the lack of a standardized methodology capable of systematically fusing fragmented public administrative data with 3D geospatial information remains a major barrier to the practical use of digital twins in administrative operations. To address this gap, this study proposes a standardized urban digital twin data construction methodology that complies with the international standard while effectively accommodating Korea’s building-related public datasets. Specifically, the OGC CityGML Building module is adopted as the reference model, and an extension is implemented to design a data model that extends and integrates heterogeneous sources—such as building height records, building register attributes, and road-name address data—within a unified standard schema. Furthermore, using Busanjin-gu, Busan Metropolitan City, as a case area, we develop high-precision LoD 1~4 building objects from aerial surveying outputs and empirically validate an end-to-end workflow by loading and visualizing the resulting dataset on a national public platform. By constructing operational digital twin data that tightly couples physical geometry with administrative semantics and verifying its feasibility in an actual platform environment, this study establishes a practical, standards-based foundation for deploying and operating geospatial digital twins in smart city and related urban governance applications.