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I sistemi di riferimento geodetici, ed i frame che li materializzano, costituiscono struttura di base che permette di confrontare coerentemente le rappresentazioni geometriche del territorio acquisite con rilievi diversi. Nell’ultimo secolo si è vista una continua evoluzione nella definizione dei frame geodetici, dovuta principalmente alle nuove esigenze, e possibilità, introdotte dalle tecniche di geodesia spaziale. È cambiata la scala alla quale si affronta il problema, sono cambiate le precisioni delle misure e delle accuratezze richieste, sono cambiati gli approcci e le definizioni. L’esigenza di un sistema di riferimento valido su scala globale ha imposto la definizione di frame dinamici, che seguano le evoluzioni della crosta terrestre nel suo complesso, introducendo così la necessità di una coordinata temporale oltre alle classiche coordinate geometriche. Proprio la natura dinamica della Terra implica delle variazioni nel tempo delle coordinate, espresse nel riferimento globale, troppo elevate per essere gestite nelle applicazioni cartografiche a scala continentale/nazionale, per cui si è resa necessaria la definizione di altri sistemi di riferimento, vincolati alle placche tettoniche. Di fondamentale importanza sono diventati quindi i parametri di conversione delle coordinate che premettono il passaggio da sistemi globali a regionali, e viceversa. Nel percorso di questa tesi ci si è occupati del monitoraggio dei frame di riferimento dinamici, in particolare di quello nazionale realizzato dalla Rete Dinamica Nazionale. È stato affrontato il problema delle velocità residue che caratterizzano il territorio italiano nel sistema di riferimento europeo, definendo un nuovo sistema ad hoc per il territorio nazionale. È stata indagata la tecnica di calcolo Precise Point Positioning, sia dal punto di vista geodetico e dell’inquadramento delle coordinate nel sistema globale, sia dal punto di vista del rilievo tecnico. Infine, ci si è occupati delle reti geodetiche diffuse sul territorio di Regione Emilia-Romagna, e della funzione che queste ancora devono avere nell’era dei GNSS., The geodetic reference systems, and the related frames, constitute the basic structure that allows to compare geometric representations of the earth acquired by different surveys. The last century has seen a continuous evolution in the definition of geodetic frames, mainly due to new needs, and possibilities, introduced by the space geodesy techniques. Are changed the scale of the problem, the precision of the measurements and the required accuracies, and also the approaches and definitions. The requirement of a global reference system has imposed the definition of dynamic frames, which follow the evolution of the earth's crust as a whole, so the need for introducing a time coordinate in addition to usual geometric coordinates. The dynamic nature of the Earth involves variations in time of coordinates, when expressed in the global reference system, too quick to be handled in mapping applications on a continental / national scale. So it was necessary the definition of other reference systems, linked to the tectonic plates. Thus, fundamental are the transformation parameters needed to switch from regional systems to global systems, and vice versa. In this thesis the topic of the monitoring of dynamic reference frames has been addressed, in particular the Italian Rete Dinamica Nazionale. The matter of the high residual ETRS velocities that characterize the Italian peninsula has been addressed, and a new ad hoc reference system was defined. The calculation technique of Precise Point Positioning has been investigated, both from the geodetic point of view, addressing the strategies to align the coordinates in the global system, than from the point of view of technical surveys. Finally, the geodetic networks of the Emilia-Romagna Region were analyzed, evaluating their importance in the age of GNSS.

The knowledge of the so-called geoid undulation, which represents the height of the geoid above a reference ellipsoid, is a fundamental step to link ellipsoidal heights measured using satellite systems and orthometric heights. Several geoid models are available at the time both at the national or global scale, which can be used for the purpose. Another way to define the geoid undulation is to perform joint measures with GNSS and spirit levelling over common benchmarks. This requires onerous measurements that is seldom possible to perform due to their cost. In this work, we evaluated the possibility to define a local model of the geoid undulation using already available spirit levelling orthometric heights and GNSS ellipsoidal heights measured about 13 years later. The test area is the Emilia-Romagna Adriatic coastline, an area of great interest both from the environmental and economic point of view, which is also undergoing consistent subsidence phenomena.Test results show that the available measurements allow defining a geoid undulation that is coherent with the shape defined by the gravimetric models and also allows to transform ellipsoidal heights into orthometric ones more consistent with the height reference available on the surveyed area. A 7 cm overall bias with respect to the ITALGEO05 was found, whereas ITG2009 and EGM2008 have higher differences. The use of subsidence models to align over time the coordinates used to define the geoid undulation has proven to be a fundamental step. The analysis on the a-priori uncertainty in the geoid height definition shown that the combined use of much more precise GNSS coordinates and contemporary spirit levelling campaign is necessary to significantly improve the resulting geoid height.

Although thermal imaging is a widely used technique in many applications and is under continuous development, one of its limits is the relatively coarse spatial resolution. Nevertheless, in the last years, a number of super-resolution algorithms have been developed which allow to enhance the resolution of the images. They can be divided in two main different categories: single-image or multiple image-based algorithms. In this work, a multiple image-based algorithm for the super-resolution was implemented, tested and applied to terrestrial thermal imaging with the aim to overcome the limitation of the low resolution. In particular, the method relies on the use of many images acquired from slightly different positions to obtain, thanks to the redundancy of observations, a super-resolution frame having an upsampling factor of four. Several tests were performed on synthetic datasets, and the accuracy of the obtained super-resolution images was investigated. Moreover, an original algorithm capable to identify gross errors during the image registration phase, which is one of the crucial phases, is presented and its reliability assessed. Results showed the effectiveness of the proposed method on both common visible images and thermal infrared ones, since discrepancies between reconstructed and reference values are reduced by 18 and 25% respectively, when compared with a conventional bicubic algorithm. Finally, the proposed method was tested on a case study concerning the thermal survey of the facade of a historical building in Bologna (Palazzo D’Accursio). A dataset of real thermal frames was acquired and a super-resolution image of the subject was generated through the developed algorithm. Strengths and weaknesses of the method were analysed and discussed in the paper.