PostGIS-Unity integration for scalable 2D/3D geospatial visualisation and querying

3D city models and interactive geospatial scenes have become increasingly used not only for visualisation, but also for simulation, spatial analysis, urban planning, and decision support. At the same time, game engines such as Unity are prominent platforms used for the development of geospatial applications, offering effective 3D rendering and interaction. However, existing workflows involving 3D geospatial data still depend on format conversions and dedicated server infrastructures for streaming spatial data, making database-centred scene management unnecessarily complex. This paper presents a PostGIS and Unity integration that explores a more direct communication between both solutions. The application supports (i) direct PostGIS-to-Unity visualisation of 3D spatial data without requiring a dedicated server, (ii) storage and retrieval of georeferenced 3D models and materials for scene loading, (iii) tile-based loading and metadata retrieval for scalable interactive environments, and (iv) query-driven scene rendering, including LLM support for spatial query generation assistance. Rather than treating the database only as a storage solution, the proposed approach positions PostGIS as an active runtime component for visualisation, querying, and update. The work is relevant for digital twins, urban visualisation, and exploratory geospatial applications where tight coupling between spatial databases, interactive 3D rendering, and AI-assisted querying is desirable.