Objectives Three-dimensional (3D) electronic maps offer significant advantages in representing the objective world with high fidelity and intuition, playing a pivotal role in the abstract simulation and cognitive analysis of complex 3D geographical environments. However, traditional 3D electronic maps often suffer from massive volumes, heterogeneous formats, and a heavy reliance on specialized geographic information system (GIS) software, which collectively impose a high technical threshold for non-professional users. In the era of informatization, ordinary users are familiar with the portable document format (PDF), and the PDF format has emerged as a globally recognized standard due to its cross-platform compatibility and high universality. To adapt to the trend of popular map application and lower the barrier for ordinary users to use maps, this paper explores the design of a new type of 3D map data organization model, namely the 3D geospatial PDF map data organization model. This model establishes a formal expression framework for 3D maps by leveraging the structural affordances of the PDF format.

Methods First, we established the theoretical foundation by elaborating on the conceptual framework of the 3D geospatial PDF map. This involved designing a hierarchical data organization structure that formalizes the transition from complex 3D map data to document-based representations. Specifically, we engineered a robust data storage schema that leverages the universal 3D (U3D) standard within the PDF object hierarchy, ensuring seamless encapsulation of 3D geometries, texture mappings, and spatial metadata. Second, to evaluate the model's robustness and cross-domain applicability, a series of mapping and analysis experiments were conducted. We utilized a diverse range of multi-source spatial datasets, including terrain elevation data, oblique photography meshes, and urban 3D models, to produce high-fidelity 3D geospatial PDF prototypes. This process validated the model's capacity to handle heterogeneous data formats and complex spatial scenes.

Results The experimental results demonstrate that: (1) Three 3D geospatial PDF maps are produced based on our 3D geospatial PDF map data organization model, with clear and beautiful visual effects. (2) The 3D geospatial PDF map has both basic map features and PDF lightweight features, namely map scene element visualization, geospatial reference, three-dimensional geographic entity structure, lightweight storage, lightweight form, and lightweight application.

Conclusions This research provides map users with a standardized and accessible 3D map solution based on the PDF format. By decoupling 3D spatial information from specialized software environments, this model significantly lowers the barrier to entry for spatial data utilization, thereby expanding the user base and broadening the application scenarios for 3D electronic maps in the digital age.