Traveling in the three-dimensional city: applications in route planning, accessibility assessment, location analysis and beyond

Indoor environments are increasingly important spaces in contemporary three-dimensional cities. Handling these micro-scale spaces within the broader context of outdoor - urban environments is a significant challenge in transportation analysis and geographic information science. This complexity stems from the greater computational requirements, the specificity of indoor network data structures, as well as the inherent perceptual intricacies of 3D visualization. As built environments grow in size and in complexity, two-dimensional urban geography research reveals its limits. This paper advocates for 3D network-based urban research and showcases the feasibility of this approach for three specific types of urban analytical functionalities, namely route planning, spatial accessibility assessment, and facility location planning. The latter modeling functionality can be viewed as foundational elements for comprehensive network-based three-dimensional analytics of urban environments. The effectiveness of the data modeling scheme and of the integrated software application 3DCityNet is discussed through the three coupled geospatial modeling functionalities.