## 2 Background and Definition of CIM
### Technology Foundation of CIM
#### 2.2.1 Building Information Modeling (BIM)  
As the foundational digital backbone of CIM, BIM constitutes a parametric semantic modeling framework that delivers comprehensive structural and operational intelligence for urban systems through object-oriented 3D digital twins [12; 13]. Originating as an architectural design innovation, BIM has evolved from supporting building-level design-construction-operation (DCO) workflows [14; 15] to enabling city-scale infrastructure lifecycle governance. This technological progression manifests through BIM-GIS interoperability standards that facilitate multi-resolution urban representations, ranging from individual building components to metropolitan infrastructure networks. Beyond geometric modeling, BIM implements multi-dimensional data schemas encompassing material properties, structural mechanics, temporal phasing, and energy performance metrics, thereby establishing a data-rich substrate for urban computational analytics. Empirical studies demonstrate BIM's capacity to optimize construction productivity, mitigate resource misallocation, and enhance risk prediction accuracy through its IFC standards-compliant data interoperability and 4D simulation capabilities [1; 16; 17]. Within the field of urban infrastructure development and management, BIM plays a pivotal role. Firstly, it is extensively applied in the construction and management of urban infrastructure. By leveraging three-dimensional digital modeling, BIM enables the precise simulation of roads, bridges, tunnels, and utility systems such as water and power supply. This capability allows the early detection of potential issues and the optimization of the design solutions during the planning phase [18; 19]. Additionally, BIM is increasingly integrated with a GIS to enhance its utility in urban planning. When integrated with a GIS, BIM provides planners detailed geometric data of buildings and infrastructure, facilitating the simulation of various urban development scenarios. This integration enables a more comprehensive evaluation of factors such as land use, traffic flow, and energy consumption, ultimately optimizing spatial layouts and promoting sustainable urban development. Moreover, BIM is widely utilized in resource management and energy efficiency optimization. By providing precise data on materials and energy consumption, BIM aids designers and urban managers in improving building energy performance, reducing resource waste, and enhancing the lifecycle management strategies for urban infrastructure. Finally, in disaster management and emergency response, BIM serves as a reliable digital platform, equipping emergency managers with accurate building structure and environmental data. This enables rapid decision making during emergencies and facilitates effective post-disaster reconstruction efforts, ensuring efficient information transmission and improving the overall disaster response capabilities. Notwithstanding the substantial advantages that BIM confers upon CIM, several persistent challenges impede its full potential. Foremost among these is the lack of standardized data formats, disparate scales, and inconsistent protocols between BIM and other systems, particularly GISs, which engenders significant barriers to seamless data exchange and collaborative analysis [18; 20]. This interoperability issue markedly constrains the efficacy of integrated urban management systems. Secondly, BIM technology exhibits limited adaptability in dynamic urban environments. During large-scale urban transformations, the real-time updating and integration of BIM data necessitate substantial optimization to enhance both the responsiveness and accuracy. This limitation is particularly pronounced in rapidly evolving urban landscapes, where timely and precise data integration is paramount for effective decision making. Moreover, the application of BIM in interdisciplinary collaboration remains underdeveloped, especially in critical domains such as environmental protection and social welfare.