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Nowadays Marine Geographical Information Systems (MGIS) play an essential role in several research activities, the most part of them related to solve Geoscience problems. The nautical maps, containing most of the information used by the marine navigators, are used as cartographic base of MGIS and widely referred to Mercator projection. Remotely sensed images can be introduced in MGIS to improve the study outcomes even if they are in a different cartographic representation (generally Universal Transverse of Mercator, UTM). The adaptation of already georeferred remotely sensed images to Mercator projection requires particular care, moreover when also geodetic data are different (i.e. local datum and global datum). This paper is aimed to offer an easy-to-use work-flow that could be adopted every time remotely sensed images are to be introduced in MGIS and overlaid to nautical maps. Particularly the work addresses the implementation and evaluation of reprojection of Landsat 8 imageries, regarding both the gulfs of Naples and Salerno (Italy): a transformation from UTM WGS84 to Mercator Roma40 is applied. The result accuracy encourages the adoption of the proposed work-flow.

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Land Cover maps supply information about the physical material at the surface of the Earth (i.e. grass, trees, bare ground, asphalt, water, etc.). Usually they are 2D representations so to present variability of land covers about latitude and longitude or other type of earth coordinates. Possibility to link this variability to the terrain elevation is very useful because it permits to investigate probable correlations between the type of physical material at the surface and the relief. This paper is aimed to describe the approach to be followed to obtain 3D visualizations of land cover maps in GIS (Geographic Information System) environment. Particularly Corine Land Cover vector files concerning Campania Region (Italy) are considered: transformed raster files are overlapped to DEM (Digital Elevation Model) with adequate resolution and 3D visualizations of them are obtained using GIS tool. The resulting models are discussed in terms of their possible use to support scientific studies on Campania Land Cover.

Global Navigation Satellite Systems (GNSS) have developed rapidly over the last few years. At present, there are GNSS receivers that combine satellites from two or more different constellations. The geometry of the satellites in relation to the receiver location, i.e. how nearly or distantly they are disposed in the sky, impacts on the quality of the survey, which is essential to achieve the highest level of position accuracy. A dimensionless number identified as Geometric Dilution of Precision (GDOP) is used to represent the efficiency of the satellite distribution and can be easy calculated for each location and time using satellite ephemeris. This paper quantifies the influence of multi-GNSS constellation, in particular GPS (Global Positioning System) and GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema) combination, on satellite geometry considering a precise period. A new index named Temporal Variability of Geometric Dilution of Precision (TVGDOP) is proposed and analyzed in different scenarios (different cut-off angles as well as real obstacles such as terrain morphology and buildings). The new index is calculated for each of the two satellite systems (GPS and GLONASS) as well as for their integration. The TVGDOP values enable the three cases to be compared and permit to quantify the benefits of GNSS integration on satellite geometry. The results confirm the efficiency of the proposed index to highlight the better performance of combination GPS+GLONASS especially in presence of obstacles.