NIU Chaoran, XUE Cunjin, XIANG Zheng, MA Ziyue
[Objectives] The ocean twin space consists of the real ocean, the virtual ocean, and the bidirectional links between them. Spatiotemporal modeling for twin spaces requires the simultaneous representation and modeling of all ocean phenomena, objects, and their relationships within the study area. However, existing models such as object-oriented models, spatiotemporal field models, event-based models, and process-based models that incorporate dynamic changes, primarily focus on modeling individual ocean phenomena, including objects, fields, events, and processes. The absence of a unified organizational structure makes comprehensive ocean environment modeling challenging. [Methods] Based on four types of ocean spatiotemporal models mentioned above, this study designs a unified spatiotemporal data organization structure and proposes a graph model for the integrated representation of oceanic static and dynamic elements in twin spaces. The core components of the model include: (1) Establishing a unified organization structure of "entity object-data description-data sequence" through hierarchical and attribute design of the entity object, enabling the unified organization of four object types: spatiotemporal objects, spatiotemporal fields, events, and processes; (2) Designing the relationship representation between oceanic static and dynamic elements in the twin space by analyzing the mapping process from the real ocean to the virtual ocean; (3) Integrating the unified structure of the four object types with the representation of relationships between static and dynamic elements, extracting five core components: time, entity object, twin object, twin scene, and relationship. Furthermore, entities and relationships within these core components are then abstracted into nodes and edges, constructing a five-layer graph representation framework: "twin scene-twin object-entity object-data sequence-time." [Results] A case study on the organizational management of ocean elements around Yin Island and its surrounding waters in the northeast of the Yongle Atoll, Xisha Islands, Sansha City, Hainan Province, China, validates the feasibility and effectiveness of the proposed graph model for integrating static and dynamic ocean elements in twin spaces. Comparative experiments with the hybrid object-field model, the geographic knowledge graph, and the geographic spatiotemporal process-based knowledge representation model demonstrate that the proposed model successfully unifies static objects and dynamic processes, providing a more comprehensive representation of relationships between ocean objects. [Conclusions] The proposed model resolves the fragmentation of static and dynamic data in twin spaces, enhances the efficiency of ocean data management and utilization, and advances ocean management from digitization to intelligence.