Nowadays, complete 3D digitalisation, the process of acquisition and elaboration of 3D metric data, has become almost a fundamental step in many fields such as cultural heritage, land survey, infrastructure, archaeology, city planning and others. In all these fields complete 3D modelling is the base for several application such as the creation of digital twins and virtual documentation, Building Information Modelling (BIM), Geographical Information System (GIS), restoration projects, valorisation project, virtual reality and augmented reality (VR & AR), and in general for long term management and monitoring of different assets. There is, therefore, a strong demand for complete and accurate 3D measurement of objects such as buildings, manufacts, infrastructure etc. to be acquired and updated in the shortest amount of time possible. Nowadays, there are already different instruments and techniques that allow for the acquisition of 3D data and high-resolution images, above all, among the most popular: terrestrial laser scanners and close-range photogrammetry. However, the available technology is not suited for all application that the market demands. The final goal of creating a digital copy, a digital twin, of everything, hits a barrier in the 3D mapping of very complex areas, above all: narrow and extensive spaces such as tunnels, spaces that can be found everywhere and are a necessary component of the aforementioned fields. Narrow spaces such as passages, staircases, tunnels, mines, catacombs, caves and the like have similar characteristics and can be found both in hand made environments and natural formations. The limited accessibility of these spaces prevents the mapping operations completely or makes them economically unsustainable for the state-of-the-art technology and tools by requiring too much time to be completed. The research work has therefore focused on the realization of a multi-camera survey tool that can complete the acquisition of data in complex areas with ease and in a short time and that at the same time can guarantee high levels of accuracy and reliability. The first phase of experimentation was based on the use of fisheye photogrammetry and the design of different low-cost multi-camera solutions mounting GoPro cameras with fisheye optics in order to exploit the advantage given by the angle of view. Subsequently, these first experiments led to the formulation of the FINE Benchmark, a dataset designed and shared with the scientific community with the aim of highlighting the limitations of a low-cost approach based on commercial sensors. Finally, the last phase was the design of a multi-camera system to improve on previous iterations. This led to the creation of a working prototype that allows three-dimensional reconstruction and photographic inspection of confined environments, both man-made and natural. It is specially designed to ensure high accuracy and repeatability of the survey. The multi-camera finds its natural application in those situations where a 360-degree digitization is required, with high-resolution 3D geometric information and complete photographic documentation. The device is able to acquire 3D data in the form of point clouds and high-resolution images to describe the area of interest in a short time. The instrument consists of a multi-camera designed to be used by hand by a single operator walking through the environment/tunnel to be surveyed, or to be used autonomously when mounted on a vehicle or unmanned system. The last chapter of this thesis shows some of the numerous tests performed in the field that have demonstrated the effectiveness of the instrumentation in achieving its objectives of speed and accuracy. The design and characteristics of the multi-camera system have led to the filing of a patent application in January 2021 (Application No. 102021000000812). In addition, the solution produced was one of the winning finalists in the Switch2Product acceleration program organized by PoliHub, Technology Transfer Office of the Politecnico di Milano and Officine Innovazione of Deloitte.
Al giorno d'oggi, la digitalizzazione 3D completa, il processo di acquisizione ed elaborazione di dati metrici 3D, è diventato un passo quasi fondamentale in molti campi quali: il patrimonio culturale, il rilevamento del territorio, le infrastrutture, l'archeologia, la pianificazione urbana e altri. In tutti questi campi la modellazione 3D completa è la base per diverse applicazioni come la creazione di digital twin e documentazione virtuale, Building Information Modelling (BIM), Geographical Information System (GIS), progetti di restauro, progetti di valorizzazione, realtà virtuale e realtà aumentata (VR & AR), e in generale per la gestione e il monitoraggio a lungo termine di diversi beni. C'è quindi una forte richiesta di misurazioni 3D complete e accurate di oggetti come edifici, manufatti, infrastrutture etc. da acquisire e aggiornare nel minor tempo possibile. Al giorno d'oggi esistono già diversi strumenti e tecniche che permettono l'acquisizione di dati 3D e immagini ad alta risoluzione, i più diffusi sono: laser scanner terrestri e close-range fotogrammetria. Tuttavia, la tecnologia disponibile non è adatta a tutte le applicazioni che il mercato richiede. L'obiettivo finale di creare una copia digitale, un digital twin, di tutto, si scontra con la barriera della mappatura 3D di aree molto complesse, soprattutto: spazi stretti ed estesi come le gallerie, spazi che si possono trovare ovunque e sono una componente necessaria dei campi citati. Spazi stretti come passaggi, scale, tunnel, miniere, catacombe, grotte e simili hanno caratteristiche confrontabili e si possono trovare sia in ambienti artificiali che in formazioni naturali. La limitata accessibilità di questi spazi impedisce completamente le operazioni di rilievo o le rende economicamente insostenibili per la tecnologia e gli strumenti ad oggi disponibili, richiedendo troppo tempo per essere completate. Il lavoro di ricerca si è quindi concentrato sulla realizzazione di uno strumento di rilievo multicamera che possa completare l'acquisizione 3D in aree complesse con facilità e in tempi brevi e che allo stesso tempo possa garantire alti livelli di precisione e affidabilità. La prima fase di sperimentazione si è basata sull'utilizzo della fotogrammetria fisheye e sulla progettazione di diverse soluzioni multicamera a basso costo che montano telecamere GoPro con ottica fisheye per sfruttare il vantaggio dato dall’ampio angolo di campo. Successivamente, questi primi esperimenti hanno portato alla formulazione del FINE Benchmark, un dataset progettato e condiviso con la comunità scientifica con lo scopo di evidenziare i limiti di un approccio low-cost basato su sensori commerciali. Infine, l'ultima fase è stata la progettazione di un sistema multicamera per migliorare le iterazioni precedenti. Questo ha portato alla creazione di un prototipo funzionante che permette la ricostruzione tridimensionale e l'ispezione fotografica di ambienti confinati, sia artificiali che naturali. È stato appositamente progettato per garantire un'elevata precisione e ripetibilità del rilievo. La multicamera trova la sua naturale applicazione in quelle situazioni in cui è richiesta una digitalizzazione a 360 gradi, con informazioni geometriche 3D ad alta risoluzione e una documentazione fotografica completa. Il dispositivo è in grado di acquisire dati 3D sotto forma di nuvole di punti e immagini ad alta risoluzione per descrivere l'area di interesse in breve tempo. Lo strumento consiste in una multicamera progettata per essere utilizzata a mano da un singolo operatore che cammina attraverso l'ambiente/tunnel da rilevare, o per essere utilizzata autonomamente se montata su un veicolo o un sistema a pilotaggio remoto. L'ultimo capitolo di questa tesi mostra alcuni dei numerosi test effettuati sul campo che hanno dimostrato l'efficacia della strumentazione nel raggiungere i suoi obiettivi di velocità e precisione. La progettazione e le caratteristiche del sistema multicamera hanno portato al deposito di una domanda di brevetto nel gennaio 2021 (Application No. 102021000000812). Inoltre, la soluzione prodotta è stata una delle finaliste vincitrici del programma di accelerazione Switch2Product organizzato da PoliHub, Technology Transfer Office del Politecnico di Milano e Officine Innovazione di Deloitte.
Image-based multicamera mobile mapping system to survey narrow spaces
Perfetti, Luca
2021/2022
Abstract
Nowadays, complete 3D digitalisation, the process of acquisition and elaboration of 3D metric data, has become almost a fundamental step in many fields such as cultural heritage, land survey, infrastructure, archaeology, city planning and others. In all these fields complete 3D modelling is the base for several application such as the creation of digital twins and virtual documentation, Building Information Modelling (BIM), Geographical Information System (GIS), restoration projects, valorisation project, virtual reality and augmented reality (VR & AR), and in general for long term management and monitoring of different assets. There is, therefore, a strong demand for complete and accurate 3D measurement of objects such as buildings, manufacts, infrastructure etc. to be acquired and updated in the shortest amount of time possible. Nowadays, there are already different instruments and techniques that allow for the acquisition of 3D data and high-resolution images, above all, among the most popular: terrestrial laser scanners and close-range photogrammetry. However, the available technology is not suited for all application that the market demands. The final goal of creating a digital copy, a digital twin, of everything, hits a barrier in the 3D mapping of very complex areas, above all: narrow and extensive spaces such as tunnels, spaces that can be found everywhere and are a necessary component of the aforementioned fields. Narrow spaces such as passages, staircases, tunnels, mines, catacombs, caves and the like have similar characteristics and can be found both in hand made environments and natural formations. The limited accessibility of these spaces prevents the mapping operations completely or makes them economically unsustainable for the state-of-the-art technology and tools by requiring too much time to be completed. The research work has therefore focused on the realization of a multi-camera survey tool that can complete the acquisition of data in complex areas with ease and in a short time and that at the same time can guarantee high levels of accuracy and reliability. The first phase of experimentation was based on the use of fisheye photogrammetry and the design of different low-cost multi-camera solutions mounting GoPro cameras with fisheye optics in order to exploit the advantage given by the angle of view. Subsequently, these first experiments led to the formulation of the FINE Benchmark, a dataset designed and shared with the scientific community with the aim of highlighting the limitations of a low-cost approach based on commercial sensors. Finally, the last phase was the design of a multi-camera system to improve on previous iterations. This led to the creation of a working prototype that allows three-dimensional reconstruction and photographic inspection of confined environments, both man-made and natural. It is specially designed to ensure high accuracy and repeatability of the survey. The multi-camera finds its natural application in those situations where a 360-degree digitization is required, with high-resolution 3D geometric information and complete photographic documentation. The device is able to acquire 3D data in the form of point clouds and high-resolution images to describe the area of interest in a short time. The instrument consists of a multi-camera designed to be used by hand by a single operator walking through the environment/tunnel to be surveyed, or to be used autonomously when mounted on a vehicle or unmanned system. The last chapter of this thesis shows some of the numerous tests performed in the field that have demonstrated the effectiveness of the instrumentation in achieving its objectives of speed and accuracy. The design and characteristics of the multi-camera system have led to the filing of a patent application in January 2021 (Application No. 102021000000812). In addition, the solution produced was one of the winning finalists in the Switch2Product acceleration program organized by PoliHub, Technology Transfer Office of the Politecnico di Milano and Officine Innovazione of Deloitte.| File | Dimensione | Formato | |
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Descrizione: PhD Thesis
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https://hdl.handle.net/10589/182993