Abstract
Abstract. Almost all official national cartographic bases in Europe include Digital Terrain Models (DTMs). To perform analyses at the borders between countries, transnational geographic information is needed: a transnational DTM can be obtained by merging regional DTMs (usually at low resolution) and other typically local high resolution DTMs. To be used the different DTMs must be in the same three dimensional reference frame, they must not present biases and must be consistent at the nominal scale. The following preliminary actions are required: • 3D reference frame transformation of gridded data, • cross-validation of the regional DTMs, • cross-check of the regional LR DTMs and the local HR DTMs. The paper discusses the study, the implementation and the application of algorithms to solve these problems in the Alpine area between Italy and Switzerland. For this case study, the regional DTMs of Lombardy, Piedmont and Switzerland, respectively with a planimetric resolution of 20, 50 and 25 meters are available. In addition, a LiDAR DTM with a planimetric resolution of 1 meter for the Lombardy and Piedmont hydrographic basins is available. The different DTMs have been transformed to the same reference frame by applying the official national 3D transformations. The cross-validation and the cross-check of the elevation datasets have been performed. All these operations have required the implementation of novel approaches to interpolate and compare DTMs and to spatially analyze their differences.
Highlights
Elevation data are fundamental in Geographical Information Systems (GIS) and one of the spatial data provided by the European Directive INSPIRE (Infrastructure for Spatial Information in Europe)
DEM refers to the generic family of elevation models: they are distinguished between Digital Surface Models (DSMs), which represent the surface and Digital Terrain Models (DTMs) which represent the elevation of bare soil
The presented research is in the framework of the Interreg ItalySwitzerland HELI-DEM (Helvetia-Italy Digital Elevation Model) project
Summary
Elevation data are fundamental in Geographical Information Systems (GIS) and one of the spatial data provided by the European Directive INSPIRE (Infrastructure for Spatial Information in Europe). They are stored in Digital Elevation Models (DEM, Li et al, 2005, El-Sheimy et al, 2005), which are the basic tools for many environmental and territorial applications. DTMs are important in Environmental Engineering, Civil Engineering and in many specific applications, such as the design of telecommunication networks or precise agriculture In recent years, both in Italy and Switzerland, elevation data with different reference frames, technologies, accuracies and data models have been acquired. The first steps of the project will be discussed: in Sect. 2 the available data are presented, in Sect. 3 the adopted strategies to cross-check the data are discussed and their application to some case studies are reported
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