High-Resolution Digital Terrain Model on a sample area of the Italian national territory

This study presents the development of a high-resolution (5 m) digital terrain model (DTM) for Italy, preparedwithin the PNRR project “National Centre for HPC, Big Data andQuantum Computing”. The goal is to enhance the accuracy ofnational-scale elevation data, improving upon the existing datasetTINITALY, originally at 10 m spatial resolution across Italy, byintegrating sparse but extensive multi-source LiDAR data.A key challenge is the heterogeneous and fragmenteddistribution of LiDAR datasets, acquired by different institutions atdifferent times, with varying resolutions, and different coordinatereference systems (CRS). To address this, a structured database hasbeen designed to allow efficient updates as new LiDAR data becomeavailable. The methodology combines high-performance computinginfrastructure with open-source software, leveraging GRASS GIS,Linux shell scripts, and data-parallel workflows to process large-scale datasets.The data processing pipeline includes automated dataprocessing, including CRS harmonization and mosaicking, ensuringa seamless and homogeneous national DTM. TINITALY data wereinterpolated to 5 m to bridge LiDAR gaps, prioritizing data recencyand resolution in overlapping areas. The workflow was tested on asample area with complex topography, validating the feasibility ofthe approach and ensuring data consistency across diverse terrains.The final product is a high-accuracy DTM, suitable forhydrological and slope stability modeling, natural hazardassessment, and environmental management. This methodology,scalable and updatable, will provide a nationally consistent dataset,enabling analyses that were previously constrained by datafragmentation and resolution limitations.