1,721,000 research outputs found
The usability of GNSS mass-market receivers for cadastral surveys considering RTK and NRTK techniques
Full text linkNowadays many positioning techniques and methods are applied to the cadastral surveys. Starting from last decade, GPS/GNSS positioning had become one of the most used methodology thanks to the rapid development of satellite-based positioning and to the appearance of GNSS mass-market receivers and antennas. Methods based on these instruments are more affordable than the conventional ones even if their use for precise positioning is not so intuitive. This study is aimed to evaluate the use of single-frequency GPS/GNSS mass-market receivers for cadastral surveys, considering both single-base Real-Time Kinematic (RTK) and Network Real-Time Kinematic (NRTK) methodologies. Furthermore, a particular tool for predicting and estimating the occurrence of false fix of the phase ambiguities has been considered, in order to improve the accuracy and precision of the solutions. Considering the single-base positioning, the research results showed the difference of a few centimetres between the reference coordinates and the estimated ones if the distance between master and rover is less than 3 km, while considering the network positioning and the Virtual Reference Station correction, the difference are about a couple of centimetres for East and North component, and about 5 cm for the Up
Inertial measurement units inside smartphones: Performances future steps
No full textInertial measurement units (IMUs) are one of the most common sensors available today in smartphones. Generally, cell phones are equipped with particular inertial sensors that may vary among different brands and models. Their characteristics, in terms of precision and accuracy, are not important for smartphone operations but they become fundamental for some activities, such as positioning and navigation. In this context, it is interesting to analyse the characteristics of different inertial platforms installed today in these mobile devices. In this chapter, the performance of different IMU mass-market platforms present in mobile devices will be analysed, considering different positioning modes available in the literature. All tests are conducted in a laboratory, considering free magnetic field conditions. To identify the flicker noise, white noise, and random noise in each device, the Allan variance of each sensor will be computed. Each dataset (acceleration and angular velocity) has also been analysed with NaveGo, a software tool, with the purpose of performing the Allan Variance procedure to quantify the level of inertial sensor stochastic errors. A brief overview of future applications will be provided at the end of this chapter
An overview about Geographic free and open-source software
Full text linkSince the last decade, numerous free and open-source software (FOSS) has been developed: this new approach, thanks to its quick update and its affordability, has guaranteed the employment of FOSS both by public and private bodies. In the field of open tools, the development of geographic software (GFOSS) became particularly relevant, whose distribution increased enormously and whose innovations are constantly increasing.This work aims to show the main innovations in the field of GFOSS in order to highlight, by macro themes, what could be the future developments in the field of open source
Smartphones recent innovations and applications
No full textSmartphones are mobile devices that perform many of the functions of a computer, typically having a touchscreen interface, Internet access, and an operating system capable of running downloaded apps. It is neither possible to cover all research fields where smartphones are used nor to describe all possible applications where smart devices are used. This book wants to highlight a selection of restricted contributions in the emerging research fields where smartphones can be used for innovative approaches. Then, this book is meant for academic researchers, engineers and for others who want to find out more about smartphone emerging technologies and future application
New photogrammetric sensors for precision agriculture: the use of hyperspectral cameras
Full text linkPhotogrammetric and remote sensing techniques are increasingly getting used in precision agriculture to improve monitoring and management of the crops and at the same time to increase the crop yield and reduce the environmental impacts derived from the treatments.The entire production sector can benefit from the advance in technologies and the development of lightweight sensors for UAV (uncrewed aerial vehicles) with a higher spectral and spatial resolution such as the hyperspectral sensors. The hyperspectral sensors' ability for measuring hundreds of bands has impacts on the complexity and the data processing. Indeed, it is necessary to handle a considerable quantity of acquired data and select the relevant information for interventions in the agricultural area. The aims of this work are providing a survey of the UAV-based hyperspectral sensors available on the market and their acquisition technology and a global view of possible applications in the agriculture field. Moreover, the paper highlights future research developments related to this new type of device
Positioning exploiting GNSS raw measurements
No full textPosition and navigation are key advancements of smartphones technology. Nowadays, any smartphone is equipped with a GNSS chip, providing the device position and time. On one side, the improvements in electronics and communications boosted the design of smaller, cheaper and power saving GNSS chips, which are now multi-constellation and multi-frequency and outperform dedicated personal positioning devices. On the other side, the availability of accurate position and time enabled the development of services and location-based applications making the smartphone a professional positioning instrument. Starting from 2016, Android smartphones provide a set of raw GNSS measurements, inaddition to the user position, which open the way to more advanced and customizable positioning algorithms. This chapter first gives an overview on GNSS, then introduces the use of GNSS in smartphones, including the latest developments. Finally, examples of positioning performances, obtained exploiting raw GNSS measurements, are reported
A GNSS low-cost RTK network: positioning and atmospheric monitoring performances in mountain areas
No full textThe utilization of low-cost devices for global navigation satellite system (GNSS) positioning has become a widespread practice globally. Numerous studies have delved into examining the use of these devices, aiming to assess their performances, unique characteristics, and potential challenges. In recent years, the focus has extended beyond pure positioning to applications in environmental monitoring, particularly in estimating atmospheric biases such as tropospheric delay. This study concentrates on harnessing continuous operating reference station (CORS) networks for GNSS positioning at elevated altitudes, evaluating the attainable precision and robustness. Additionally, particular analyses are made to tropospheric estimations derived from rover devices through post-processing applications. While these approaches have often been implemented in the past using networks composed of geodetic receivers, this study has considered the Centipede RTK network, consisting exclusively of low-cost devices. Two different types of rovers are considered: a professional-grade and a low-cost one, aiming to analyze the achievable performances and differences between them. Three different test sites have been selected, ranging from an altitude of approximately 1470 m to 2540 m in a mountainous area close to Turin (NW Italy). After some analyses and comments based on the obtained results, some future perspectives are provided for the readers
Analisi e monitoraggio della pista dell’Aeroporto “C. Colombo” di Genova tramite rilievo GNSS e livellazione di precisione
No full textIl presente lavoro nasce dall’esigenza dell’Ente che gestisce l’Aeroporto “C. Colombo” di Genova
di monitorare lo stato della pista dal punto di vista altimetrico, al fine di individuarne deformazioni
o spostamenti.
Per raggiungere lo scopo prefissato, gli Autori hanno deciso di integrare tre tecniche diverse: il
rilievo GNSS in RTK (Real Time Kinematic) in appoggio alla Rete di Stazioni Permanenti della
Regione Liguria, il rilievo con laser scanner e la livellazione geometrica di precisione
Loosely coupled GNSS and UWB with INS integration for indoor/outdoor pedestrian navigation
Full text linkThe growth of location-based services (LBS) has increased rapidly in last years, mainly due to the possibility to exploit low-cost sensors installed in portable devices, such as smartphones and tablets. This work aims to show a low-cost multi-sensor platform developed by the authors in which an ultra-wideband (UWB) indoor positioning system is added to a classical global navigation satellite systems–inertial navigation system (GNSS-INS) integration, in order to acquire different synchronized data for further data fusion analysis in order to exploit seamless positioning. The data fusion is based on an extended Kalman filter (EKF) and on a geo-fencing approach which allows the navigation solution to be provided continuously. In particular, the proposed algorithm aims to solve a navigation task of a pedestrian user moving from an outdoor space to an indoor environment. The methodology and the system setup is presented with more details in the paper. The data acquired and the real-time positioning estimation are analysed in depth and compared with ground truth measurements. Particular attention is given to the UWB positioning system and its behaviour with respect to the environment. The proposed data fusion algorithm provides an overall horizontal and 3D accuracy of 35 cm and 45 cm, respectively, obtained considering 5 different measurement campaigns
Posizionamento GNSS per il tempo reale: prime applicazioni con un software prototipale per misure di codice
No full textLa diffusione delle Stazioni Permanenti GNSS (Global Navigation Satellite System) favorisce l'utilizzo della tecnica di posizionamento differenziale, permettendo così di ottenere precisioni soddisfacenti già in tempo reale, ossia durante la stessa fase del rilievo in campagna.
Il presente lavoro si inquadra nell'ambito delle ricerche svolte dal laboratorio di Geodesia, Geomatica e GIS dell'Università degli Studi di Genova, inerenti le problematiche connesse con la progettazione delle reti di stazioni permanenti GNSS e l’analisi dei possibili servizi per il posizionamento satellitare in tempo reale. Il principale obiettivo è quello di realizzare un codice di calcolo che, a partire dall’elaborazione in tempo reale di una rete di stazioni permanenti, possa fornire le informazioni necessarie per il posizionamento differenziale di un generico utente in appoggio alla rete stessa. Diverse sono le tecniche attraverso le quali giungere ad un cosiddetto posizionamento NRTK (Network Real Time Kinematic), basandosi sulla conoscenza dei principali effetti agenti sulle osservazioni delle singole stazioni permanenti, parametrizzati nelle cosiddette equazioni di osservazione indifferenziate o alle differenze zero. Attraverso tale approccio è così possibile modellare i principali effetti attesi sulle osservazioni per un generico utente, operante nel territorio coperto dalla rete, interpolando i parametri tra loro spazialmente correlati in funzione della posizione approssimata dell’utente stesso.
Il presente lavoro affronta una prima applicazione di posizionamento GNSS in tempo reale mediante software prototipali, scritti per mezzo del programma di calcolo Matlab, realizzati nel suddetto laboratorio. I risultati ottenuti dalle prime prove sperimentali si ritengono soddisfacenti, in quanto il confronto tra le coordinate desunte dalla monografia ed il posizionamento effettuato dal rover in appoggio alla rete sperimentale ha raggiunto una discreta stabilità sin dalle prime epoche, con differenze submetriche per quanto riguarda la planimetria e metriche per l’altimetria
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