A monitoring of presence, location and activity of various objects on the sea is essential for maritime navigation and collision avoidance. Mariners normally rely on two complementary methods of the monitoring: radar and satellite-based aids and human observation. Though radar aids are relatively accurate at long distances, their capability of detecting small, unmanned or non-metallic craft that generally do not reflect radar waves sufficiently enough, is limited. The mariners, therefore, rely in such cases on visual observations. The visual observation is often facilitated by using cameras overlooking the sea that can also provide intensified infra-red images. These systems or nevertheless merely enhance the image and the burden of the tedious and error-prone monitoring task still rests with the operator. This thesis addresses the drawbacks of both methods by presenting a framework consisting of a set of machine vision algorithms that facilitate the monitoring tasks in maritime environment. The framework detects and tracks objects in a sequence of images captured by a camera mounted either on a board of a vessel or on a static platform over-looking the sea. The detection of objects is independent of their appearance and conditions such as weather and time of the day. The output of the framework consists of locations and motions of all detected objects with respect to a fixed point in the scene. All values are estimated in real-world units, i. e. location is expressed in metres and velocity in knots. The consistency of the estimates is maintained by compensating for spurious effects such as vibration of the camera. In addition, the framework continuously checks for predefined events such as collision threats or area intrusions, raising an alarm when any such event occurs. The development and evaluation of the framework is based on sequences captured under conditions corresponding to a designated application. The independence of the detection and tracking on the appearance of the sceneand objects is confirmed by a final cross-validation of the framework on previously unused sequences. Potential applications of the framework in various areas of maritime environment including navigation, security, surveillance and others are outlined. Limitations to the presented framework are identified and possible solutions suggested. The thesis concludes with suggestions to further directions of the research presented.

This thesis is dedicated to the special class of bistatic SAR, where the transmitter is a Global Navigation Satellite System (GNSS) and receiver is fixed on the ground. Such a kind of geometry is suited for ground deformation monitoring. The employment of such a navigation satellite brings many advantages, such as shorter satellite revisit time (8-9 days) compared to imaging radar such as Envisat (35days). Moreover, due to large number of satellites deployed (at least 4 satellites could be seen at any time), persistent monitoring of a given area can be achieved from multiple angles simultaneously. This thesis presents research results on the imaging capability of SS-BSAR with GNSS and a stationary receiver. Firstly, the system is outlined and the reason of selecting GNSS as transmitter of opportunity is justified. The power budget and resolution were then analyzed. The end to end signal processing, from received raw data leading to SS-BSAR image, is described. Four experimental data sets acquired at different imaging scenarios are used to test our system hardware and signal processing algorithms mentioned below. It can be seen from the obtained images and associated analysis that such a system has the capability of real scene imaging.

Global Navigation Satellite Systems (GNSS) based high-precision positioning techniques have been widely used in geodesy, attitude determination, engineering survey and agricultural applications. With the modernisation of GNSS, the number of visible satellites and new signals are increasing. Multi-constellation and multi-frequency data provide users with more observations, and hence increase redundancy in parameter estimation. However, increased number of satellites may increase the chance of multipath errors, especially in difficult environments. Therefore, this thesis aims at characterising the measurement signal quality of all available and new signals of multi-GNSS (GPS, GLONASS, Galileo, BDS, and QZSS) with real data. Also, a new multipath detection model based on machine learning methods is developed. The measurement noise levels in all currently available signals have been studied by investigating their double difference (DD) carrier phase residuals. The positioning precision, accuracy, and ambiguity success rate have been assessed using the selected individual GNSS constellations and their selected combinations with static and kinematic antennas in low multipath and severe multipath environments. The statistical results show the residuals vary from 0.5 mm to 2 mm with different signals and models of receivers. Short baseline tests show that in ideal conditions (i.e., a low multipath environment), using a single GNSS constellation (GPS, GLONASS, Galileo, or BDS) or their combinations can usually achieve millimetre-level precision and centimetre-level accuracy with almost 100% ambiguity success rates, regardless if the rover antenna is static or kinematic. In realistic condition (i.e. a severe multipath environment) the positioning precision and accuracy reduce to the centimetre level or even worse with a kinematic antenna. Multipath effect is one of the major error sources in GNSS positioning. Most of the currently available multipath detection and mitigation methods are based on stochastic modelling, advanced techniques in data processing, spatial geometry modelling, and special hardware designs. A new machine learning based multipath detection model is developed for undifferenced measurements (a single receiver approach). The approach is based on the fact that the multipath signature can be found in the multipath contaminated time series, and the features of multipath signature can be learned and identified by machine learning methods. The proposed model has been trained and validated with simulated data in an urban canyon environment with different satellite geometries. Moreover, the model has been trained and tested with real kinematic LoS and multipath data collected with a rotating arm rig in a multipath environment, and tested with multipath data collected near solar panels and near a building. The model has been tested using all available GNSS signals. The results show the model can achieve accuracy of 80%-90% with the simulated GNSS (GPS, Galileo, and BDS) data, and accuracy of 65%-70% with the real data collected using rotating arm rig on GPS L1 and GLONASS L1 signals. Real data collected near solar panels and near a building show that the well-trained model can achieve accuracy of about 60% in completely different multipath environments. The test results show the model was not well trained on GLONASS L2 and BDS data due to their carrier multipath errors are close to their carrier measurement error in ideal environment (low multipath environment).

The increasing importance of satellite navigation technologies in modern society implies that a deeper knowledge and a reliable monitoring of the scintillation phenomena are essential to warn and forecast information to the end users and system designers. In fact, warnings, alerts and forecasting of ionospheric conditions may wisely tune the development of GNSS-based services to obtain the necessary levels of accuracy, integrity, and immediacy for reliable life-critical applications. The PhD research project is within the framework of the longstanding NGI-INGV collaboration, increasingly consolidated in the framework of many international projects. NGI pioneered GPS ionospheric scintillation monitoring in Northern Europe with GISTM (GPS ionospheric scintillation and TEC monitor, Van Dierendonck et al., 1993; Van Dierendonck, 2001) receivers. Between June 2001 and December 2003, four units were installed in the UK and Norway mainland, covering the geographic latitudes from 53° N to 70° N. Data was stored and analysed, focusing on statistical analyses and impact for GNSS users (Rodrigues et al., 2004, Aquino et al., 2005a, Aquino et al., 2005b). These units were decommissioned in 2004 and, then, re-deployed together with additional new receivers, in UK, Norway, Italy and Cyprus. An additional station was deployed by the NGI in Dourbes, Belgium (in collaboration with the Royal Meteorological Institute of Belgium) between 2006 and 2011. INGV leads the ISACCO (Ionospheric Scintillation Arctic Campaign Coordinated Observations) project in the Arctic, started in 2003, in which frame the management of three GISTM receivers in Svalbard (De Franceschi et al., 2006) and another two at European mid-latitudes, Chania (Greece) and Lampedusa (Italy), is currently undertaken. The PhD research project contributed to the reinforcement of the NGI-INGV GISTM network developing monitoring, data management and quality tools. Such activities have supported the continuity and the control of the receiving stations, as well as the access and the preservation of the both real-time and historical data acquired. In fact, a robust, continuous data acquisition and a wise management of the GISTM network are of paramount importance for Space Weather applications, as they are the basis on which reliable forecasting and now-casting of possible effects on technological systems lean. Moreover, the possibility to use the data for scientific and applicative purposes depends upon well-established data quality procedures and upon a detailed knowledge of the sites in which each receiver comprising the network are deployed. Starting from these considerations, and in the framework of the aforementioned collaborative context, the PhD work aimed at improving the monitoring techniques and developing novel data processing to improve the data quality. Scintillation measurements are contaminated by multiple scattering encountered by the GNSS signal due to buildings, trees, etc. Such multipath sources need to be identified to keep the quality of the scintillation and TEC data as higher as possible. This can be achieved by removing these sources of errors or mitigating their effects by filtering the data. A novel station characterization technique has been introduced, developed and discussed in this thesis. The results demonstrated that this is a promising method to improve the quality of data (Romano et. al 2013). The results obtained so far motivated the development of the data filtering procedures. The filtering was aimed at filtering-out spurious, noisy data based on general assumptions about statistical data analysis (outlier analysis), thus efficiently removing multipath affected measurements and reducing the data loss with respect to applying a fixed elevation angle cut-off threshold. This is particularly important in case of not well covered regions (e.g. forests, deserts, oceans, etc.), as the field of view spanned by each antenna is optimized. During the PhD activities, the filtering technique has been also tested and validated against real and simulated data. To show how the development of the filtering method is able to efficiently clean multipath and signal degradation from GNSS data, it was applied in two different cases: - First, it was applied to the data published in a climatological study (Alfonsi et al. 2011), carried out with the NGI-INGV GISTM network at high-latitudes. Each station was characterized using the station characterization method, and then the data were filtered using the filtering method. Then, the new climatological maps were generated and compared to the original ones. The percentage of the filtered-out data obtained by applying the standard threshold of 20° on the elevation angle and the filtering technique for each station demonstrated how the latter is able to meaningfully reduce the data loss. The filtering extends the field of view of the network and, then, improves the capability of investigating the dynamics of the ionosphere over larger areas. - Second, the data used in this application were acquired by the CIGALA/CALIBRA network of PolaRxS receivers during the whole year of 2012. The elevation angle cut-off significantly reduced the capability of the network to depict the ionosphere northward of the geomagnetic equator and above the Atlantic Ocean, east of Brazil. This approach limited the data loss to 10-20%, while the traditional cut off of 15°-30° on the elevation angle led to losses of 35-45%. This method not only optimized the capability of GNSS networks, but also helped in planning the installation of additional new receivers aiming to enlarge network coverage in the framework of the CALIBRA project. The enlarged field of view made it possible to identify the increased occurrence of scintillation along the northern crest of the Equatorial Ionospheric Anomaly (EIA). To summarize and to introduce the reader into this thesis, specific issues here addressed are: - Development of software procedures and hardware designs to optimize the station configurations of the existing measurement network of GISTM (GPS Ionospheric Scintillation and TEC Monitor). - Development of techniques for remote, automatic instrument control and setting. - Development of data management tools to achieve quasi real-time data accessibility. - Development of data analysis methods to assess station characterization. - Development of techniques to perform data quality filtering. - Perform acquisition of experimental and simulation data. - Support scientific investigations through the high quality of the NGI-INGV network data.

Automatic Identification System (AIS) was introduced with the overall aim to promote efficiency and safety of navigation, protection of environment, and safety of life at sea. Consequently, ship-borne AIS was implemented on a mandatory basis by IMO in 2000 and later amendments to chapter V of Safety of Life at Sea (SOLAS) Convention. Therefore SOLAS Convention vessels were required to carry AIS in a phased approach, from I" July 2002 to end of December 2004. The intention is to provide more precise information and a clear traffic view in navigation operations, particularly in anti-collision operation. This mandatory implementation of AIS has raised a number of issues with respect to its success in fulfilment of the intended role. In order to improve the efficiency of the AIS in navigation operation, this research mainly focused on the accuracy of AIS information, and practical use of the technology on board the ships. The intentions were to assess reliability of data, level of human failure associated with AIS, and the degree of actual use of the technology by navigators. This research firstly provided impressions about AIS technology for anti-collision operation and other marine operation and, about a system's approach to the issue of human failure in marine risk management. Secondly, this research has assessed reliability of AIS data by examination of data collected through three AIS data studies. Thirdly, it has evaluated navigators' attitude and behaviour to AIS usage by analysing the data from navigators' feedback collected through the AIS questionnaire survey focused on their perceptions about different aspects of AIS related to its use. This research revealed that some aspects of the AIS technology and some features of its users need further attention and improvement, so as to achieve its intended objectives in navigation. This study finally contributed in proposing the AIS User Satisfaction Model as a suitable framework for evaluation of navigators' satisfaction and extent of the use of AIS. This model can probably be used as the basis for measuring navigators' attitude and behaviour about other similar maritime technologies.

A l'instar d'autres domaines d'activités, l'environnement du marin s'est enrichi d'appareils électroniques à des fins d'aide à la navigation et de sécurité. Dans le cas de la navigation maritime, ces dispositifs ont pour principal but de donner des informations sur l'environnement dans lequel évolue le bateau: profondeur d'eau, bouées de signalisation par exemple et sur son état: cap, vitesse, etc. La complexité et le nombre d'appareils à bord des bateaux dépendent de la taille du bateau, d'un GPS portatif pour un jet-ski à un ensemble complexe d'ECDIS, de radar et d'AIS sur les cargos. Aujourd'hui, malgré l'évolution des appareils d'aide à la navigation, les accidents perdurent (échouage et collisions) et sont en partie dus aux erreurs humaines (33%). Il existe 3 grandes causes:- La charge cognitive trop importante. Cette dernière est liée à la complexité des appareils (ECDIS par exemple) [Jie and Xian-Zhong, 2008], leurs nombres et leurs orientations différentes de la vue pont [Prison and Porathe, 2007].- La mobilité de l'information. La majorité des appareils électroniques à bord des bateaux est positionné à un endroit et ne permet pas l'accès aux données en dehors de cet emplacement.- Le manque de pratique de plaisanciers. Les règles de navigation sont indispensable à la sécurité du marin et peuvent être oubliées par manque de pratique et causent des incidents (ou accidents). Dans ces travaux, nous proposons une solution mobile pour rendre accessible Les données en tout point du bateau. De plus, le prototype est basé sur la technologie de réalité augmentée pour afficher les données dans le champ de vision de l'utilisateur pour une réduction de la charge cognitive. Enfin l'application exécutée sur le prototype délivre uniquement les informations essentielles pour une navigation sécurisée. La première partie de cette thèse détaille une étude utilisateur menée pour comprendre les habitudes et les besoins des plaisanciers afin de sélectionner les données à afficher et leur représentation graphique. Suite à cette étude, une analyse du besoin logiciel et matériel a été menée. Le but de cette analyse est de lister les différents éléments pouvant supporter les contraintes maritimes (soleil, brouillard, nuit, houle, mobilité) afin de proposer un appareil et une application mobile sur technologie de réalité augmentée. La deuxième partie de cette thèse aborde le design du prototype (architecture, display) et du logiciel. Cet ensemble a pour but d'aider le plaisancier lors de conditions météos difficiles. La technologie mise en œuvre dans ce nouvel outil est la réalité augmentée, plus précisément Optical See-through. Le principe de l'application exécutée sur le prototype est un serveur proposant des services à l'utilisateur en fonction des appareils disponibles à bord du bateau tout en limitant la charge cognitive du marin. En effet, l'application conserve uniquement les informations utiles et les affiche dans le champ de vision de l'utilisateur, de plus elles sont superposées à sa vue directe sur le monde.La dernière partie, elle, décrit le générateur de carte qui nous permet d'extraire les données maritimes issues de différents formats de carte pour les adapter au format 3D utilisé dans l'application. Ce dernier est capable de placer automatiquement des objets 3D pour représenter le système de balisage, les amers, etc. Ce générateur a été développé pour reconstituer des zones interdites comme les zones de profondeurs, d'interdiction de chasse sous-marine, etc. Ceci a été mis en œuvre afin de répondre au mieux aux besoins de tous types de plaisanciers, de l'utilisateur de jet-ski au yacht et du pêcheur au plongeur amateur par exemple. / Compared to the other activities, the sailor's environment has been enhanced with electronic devices in order to help the sailor and improve the security. In case of maritime navigation, these devices are mainly used to give information on the environment which the boat moves such as the water depth, seamarks for instance and its state: bearing, speed, etc. The complexity and the number of devices onboard depend on the boat size, from a wearableGPS on a jet-ski to a complex set of ECDIS, radar and AIS on a merchant ship. Today, despite the evolution of the navigational aid devices, the accidents still happen and they are due in part to human errors (33%). There are 3 main causes: The cognitive load issue. The latter is linked to the complexity of devices (ECDIS for instance [Jie and Xian-Zhong, 2008]); their quantity and their orientations which is different from the bridge view or the user's field of view [Prison and Porathe, 2007]. The information's mobility. Most of the devices onboard are put in a specific place and the data are not accessible outside this place. The lack of practice of the recreational boats owner. The maritime navigation rules are vital to sail safely but some of sailors can forget some significations and an accident may result from a wrong choice.In this thesis, we provide a mobile solution to make accessible data everywhere on the boat. Furthermore, the prototype is based on the augmented reality technology to display data in the user's field of view to reduce cognitive load. Finally, the application run on the prototype delivers only the relevant information for a safe navigation. The first part in this thesis details a user study conducted to understand the sailor's habits and their needs in order to select data to display and their graphical representation. Following this study, a needs analysis on the software and hardware has been realized. The purpose of this analysis is to list the different elements that are usable under maritime constraints (sun, fog, night, swell, mobility) in order to provide a device and a mobile application based on the augmented reality technology.The second part in this thesis reaches the prototype (architecture, display) and the software design. Both of them aim to help the sailors when the weather is bad. The technology used in this new tool is the augmented reality, more precisely an Optical see-Through system. The principle of the application run on the prototype is like a server, which provides services to the user depending on devices available onboard, while limiting the sailor's cognitive load. Indeed, the applications keeps only the useful data and display them in the user's field of view, furthermore they are superimposed on his/her direct view of the world.The last part in this thesis details the chart generator, which allows us to extract maritime data from different chart formats to adopt the 3D one used in the application. The latter is able to automate the placement of the 3D objects to build the buoyage system, landmarks, etc. This generator has been developed to recreate the danger areas such as depth areas, prohibited diving areas and so on. This has been done to satisfy user's expectations from the jet-ski to the yacht owner and the fisher man to the diver for instance.

Electron density irregularities influence Global Navigation Satellite System (GNSS) signals, manifesting as ionospheric scintillation. Scintillation poses a service risk to safety-critical GNSS applications at high latitudes. It is difficult to predict, as ionospheric instability processes are not yet fully characterised. This research combines the fields of ionospheric imaging and scintillation monitoring, to investigate the causes of scintillation in the Antarctic and Arctic. Results revealed a plasma patch structure above Antarctica, in response to the impact of a solar wind shock front. Measurements from a network of Global Positioning System scintillation receivers across the continent revealed moderate levels of phase scintillation associated with Total Electron Content (TEC) gradients at the patch break-off point. Scintillation was also driven by solar particle precipitation at E and F region altitudes, verified with in situ spectrometers on polar-orbiting satellites. The current receiver coverage in the region provided the Multi-Instrument Data Analysis Software (MIDAS) tomography tool with sufficient data to track the lifetime of the plasma patch without a convection model. A second experiment was performed at the South Pole, using a collocated GPS scintillation receiver and auroral imager. This allowed simultaneous line-of-sight tracking of GPS signals through the optical auroral emissions. Results showed the first statistical evidence that auroral emissions can be used a proxy for ionospheric irregularities causing GPS scintillation. The relationship was strongest during the presence of discrete auroral arcs. Correlation levels of up to 74% were found over periods of 2-3 hours. The use of multiple emission wavelengths provided basic altitude discrimination. Current capability of ionospheric TEC mapping in the Arctic was tested, where GPS receiver distribution is extensive compared to present Antarctic coverage. Analysis of the ionosphere’s response to a storm event revealed a sequential picture of polar cap patch activity, without the aid of plasma convection modelling. The electron density enhancements of the auroral oval were imaged in completeness for the first time using GPS tomography. Reconstructions were verified using ultraviolet auroral imagery from polar-orbit satellites, and vertical profiles from an incoherent scatter radar.

L’objectif de la thèse est de développer un nouveau système de localisation mobile composé de trois caméras 3D de type Kinect et d’une caméra additionnelle de type Fish Eye. La solution algorithmique est basée sur l’odométrie visuelle et permet de calculer la trajectoire du mobile en temps réel à partir des données fournies par les caméras 3D. L’originalité de la méthodologie réside dans l’exploitation d’orthoimages créées à partir des nuages de points acquis en temps réel par les trois caméras. L’étude des différences entre les orthoimages successives acquises par le système mobile permet d’en déduire ses positions successives et d’en calculer sa trajectoire. / The aim of the thesis is to develop a new kind of localization system, composed of three 3D cameras such as Kinect and an additional Fisheye camera. The localization algorithm is based on Visual Odometry principles in order to calculate the trajectory of the mobile platform in real time from the data provided by the 3D cameras.The originality of the processing method lies within the exploitation of orthoimages processed from the point clouds that are acquired in real time by the three cameras. The positions and trajectory of the mobile platform can be derived from the study of the differences between successive orthoimages.