Data sources for territorial digital twins: origin, quality and complementarity
A territorial digital twin is not a static model but a computational representation that requires continuous and heterogeneous feeding of geospatial data. The quality of the twin depends directly on the coherence between the sources that supply it, each with its own characteristics of spatial resolution, update frequency, delivery latency and conditions of use. The integration of these sources constitutes a data engineering exercise as demanding as the modelling of the physical environment itself. Satellite observation provides global coverage and periodic revisit, with capture capability in optical, synthetic aperture radar and thermal infrared bands. Its principal operational limitation is the dependence on orbital geometry for pass frequency and, in the optical case, cloud cover. Radar systems mitigate this constraint by operating independently of atmospheric conditions, although their interpretation requires more complex processing chains. The latency between capture and the availability of the processed data is a critical parameter for infrastructure monitoring or emergency management applications. Aerial capture — by means of crewed aircraft or unmanned systems — offers metric or sub-metric resolutions and greater temporal flexibility in areas of specific interest, but its coverage is localised and its operational cost per unit area is significantly higher than that of satellite data. It complements orbital data in situations requiring high geometric detail or on-demand updating. In situ sensors, for their part, provide direct measurements of physical variables — temperature, humidity, structural deformation, water level — at high temporal frequency but with discrete spatial coverage. Their integration into the twin requires interpolation models and management of the uncertainty associated with the density of the sensor network. Official cartography constitutes the reference layer upon which the other sources are anchored. Produced by national or European bodies to audited positional quality standards, it defines the geodetic and topological framework of the twin. Its principal limitation is the update frequency, which may not reflect recent changes in the territory. The harmonisation between reference cartography and dynamic observation data is one of the central technical challenges in the construction of digital twins for critical infrastructure operators and public administrations. For mission-critical environments, the governance of data sources is as relevant as their intrinsic quality. Aspects such as the traceability of the chain of custody, licence conditions, data sovereignty and interoperability with European regulatory frameworks — particularly within the scope of the INSPIRE directive and spatial data services — determine the real viability of a digital twin in institutional contexts. The selection and combination of sources must respond to defined operational requirements, not to technological availability.
NASSAT - Network Satellite Systems