4,189 research outputs found

    Comparative Analysis of Mobile 3D Scanning Technologies for Design, Manufacture of Interior and Exterior Tensile Material Structures and Canvasman Ltd. Case Study

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    This report aimed to investigate mobile 3D Scanning technologies to improve the 3D data capture and efficiency into Canvasman’s CAD design and manufacturing processes with focus on accurate resolution. The Santander funded Collaborative Venture Fund (CVF) project has provided research, survey data, evaluation and analysis for Canvasman Ltd. on 3D portable scanning hardware and software. The project solutions recommended in this report offers impartial product information on the current appropriate 3D scanning technology that potentially could improve efficiency of data capturing, design and manufacture of interior and exterior spaces, boats, vehicles and other similar constructions for creating and installing flexible coverings and indoor and outdoor structures

    Remote sensing for three-dimensional modelling of hydromorphology

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    Successful management of rivers requires an understanding of the fluvial processes that govern them. This, in turn cannot be achieved without a means of quantifying their geomorphology and hydrology and the spatio-temporal interactions between them, that is, their hydromorphology. For a long time, it has been laborious and time-consuming to measure river topography, especially in the submerged part of the channel. The measurement of the flow field has been challenging as well, and hence, such measurements have long been sparse in natural environments. Technological advancements in the field of remote sensing in the recent years have opened up new possibilities for capturing synoptic information on river environments. This thesis presents new developments in fluvial remote sensing of both topography and water flow. A set of close-range remote sensing methods is employed to eventually construct a high-resolution unified empirical hydromorphological model, that is, river channel and floodplain topography and three-dimensional areal flow field. Empirical as well as hydraulic theory-based optical remote sensing methods are tested and evaluated using normal colour aerial photographs and sonar calibration and reference measurements on a rocky-bed sub-Arctic river. The empirical optical bathymetry model is developed further by the introduction of a deep-water radiance parameter estimation algorithm that extends the field of application of the model to shallow streams. The effect of this parameter on the model is also assessed in a study of a sandy-bed sub-Arctic river using close-range high-resolution aerial photography, presenting one of the first examples of fluvial bathymetry modelling from unmanned aerial vehicles (UAV). Further close-range remote sensing methods are added to complete the topography integrating the river bed with the floodplain to create a seamless high-resolution topography. Boat- cart- and backpack-based mobile laser scanning (MLS) are used to measure the topography of the dry part of the channel at a high resolution and accuracy. Multitemporal MLS is evaluated along with UAV-based photogrammetry against terrestrial laser scanning reference data and merged with UAV-based bathymetry to create a two-year series of seamless digital terrain models. These allow the evaluation of the methodology for conducting high-resolution change analysis of the entire channel. The remote sensing based model of hydromorphology is completed by a new methodology for mapping the flow field in 3D. An acoustic Doppler current profiler (ADCP) is deployed on a remote-controlled boat with a survey-grade global navigation satellite system (GNSS) receiver, allowing the positioning of the areally sampled 3D flow vectors in 3D space as a point cloud and its interpolation into a 3D matrix allows a quantitative volumetric flow analysis. Multitemporal areal 3D flow field data show the evolution of the flow field during a snow-melt flood event. The combination of the underwater and dry topography with the flow field yields a compete model of river hydromorphology at the reach scale.Jokien onnistunut hallinta edellyttÀÀ virtavesien prosessien ymmÀrtÀmistÀ. TÀmÀ ei ole mahdollista ilman jokien geomorfologian ja hydrologian kvantifiointia sekÀ niiden spatiotemporaalisten suhteiden tutkimista, eli jokien hydromorfologiaa. Joen topografian mittaaminen, varsinkin uoman vedenalaisen osalle on pitkÀÀn ollut työlÀstÀ ja aikaa vievÀÀ. VirtauskentÀn kattava mittaaminen on myös ollut haastavaa, sillÀ seurauksella, ettÀ niitÀ on tehty harvakseltaan luonnollisessa ympÀristössÀ. Viimeaikainen teknologinen kehitys kaukokartoituksessa on mahdollistanut synoptisen tiedon mittaamisen jokiympÀristöissÀ. TÀssÀ vÀitöstutkimuksessa on kehitetty virtavesien kaukokartoitusta sekÀ jokien topografian ettÀ virtausmittauksen alalla. Useita eri lÀhikaukokartoitusmenetelmiÀ yhdistÀmÀllÀ on tehty korkean resoluution yhtenÀinen empiirinen malli joen hydromorfologiasta, eli joen uoman ja tulvatasangon topografiasta ja kolmiulotteisesta virtaamakentÀstÀ. Empiriaan ja hydrauliseen teoriaan perustuvat optisen kaukokartoituksen menetelmiÀ testattiin ja arvioitiin kÀyttÀmÀllÀ normaalivÀri-ilmakuvia, kaikuluotain kalibrointia ja referenssimittauksia kivipohjaisessa subarktisessa joessa. EmpiiristÀ optista syvyysmallia kehitettiin edelleen lisÀÀmÀllÀ syvÀn veden sÀteilyparametrin arviointialgoritmi, joka mahdollisti mallin kÀytön myös matalavetisissÀ jokiuomissa. Parametrin vaikutus malliin arvioitiin korkean resoluution matalailmakuvista hiekkapohjaisessa subarktisessa joessa yhdessÀ ensimmÀisistÀ syvyysmalleista, joka on tehty kÀyttÀen kauko-ohjattua minihelikopteria (eng.UAV, Unmanned Aerial Vehicle). LÀhietÀisyyden kaukokartoitusmenetelmiÀ kÀytettiin edelleen topografisen mallin tÀydentÀmiseen, integroimalla joen uoma ja tulvatasanko yhtenÀiseksi korkean resoluution topografiaksi. Mobiilia laserkeilausta kÀytettiin vedenpinnan ylÀpuolisen osan topografian mittaamiseen korkealla resoluutiolla vene- kÀrry- ja reppupohjaisten kartoitusalustojen avulla. Monen ajankohdan mobiilin laserkeilauksen ja UAVfotogrammetrian tarkkuutta arvioitiin maalaserikeilausaineiston avulla. Laserkeilattu ja fotogrammetrinen aineisto yhdistettiin, jolloin saatiin kahden vuoden ajalta saumaton digitaalinen maastomalli. Mallin avulla oli mahdollista arvioida koko joen uoman korkean resoluution muutosanalyysin metodologiaa. Kaukokartoitukseen perustuvaa hydromorfologista mallia tÀydennettiin uniikilla virtauskentÀn kolmiulotteisella kartoitusaineistolla. Kauko-ohjattavaan veneeseen asennettu akustinen virtausmittauslaite yhdessÀ tarkan satelliittipaikannusjÀrjestelmÀn kanssa mahdollistivat alueellisesti valikoitujen kolmiulotteisten virtausvektoreiden sijainnin mÀÀrittÀmisen kolmiulotteisessa avaruudessa pistepilvenÀ. TÀmÀn aineiston kolmiulotteinen interpolaatio matriisiksi mahdollisti edelleen volymetrisen virtausanalyysin. Monen ajankohdan alueellinen kolmiulotteinen virtauskenttÀ osoitti virtausolosuhteiden evoluution kevÀttulvassa. Vedenalaisen ja kuivan maan topografia yhdessÀ jokiuoman virtauskenttien kanssa muodosti kattavan mallin joen hydromorfologiasta.Siirretty Doriast

    New Tools for Urban Analysis: A SLAM-Based Research in Venice

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    This research proposes a detailed analysis of the potential of MMS (Mobile Mapping Systems), supported by SLAM (Simultaneous Localisation And Mapping) algorithms, performed on a multiscale test field in order to make a concrete contribution to the morphological study of cities. These systems, developed with the aim of acquiring a large number of points in a short time, are able to map the surrounding area and automatically localise themselves in real time in relation to a determined reference system. The analysed area, located in Venice, was divided into three different test fields characterised by typical elements potentially comparable to those of other urban realities. The data were acquired using the LiBackPack C50, Kaarta Stencil and Heron Lite systems and compared quantitatively and qualitatively with data obtained from more traditional surveying techniques. Specifically, the data obtained from TLS (Terrestrial Laser Scanning) surveys, supported by topographic measurements, were the most accurate basis on which to evaluate the accuracy and completeness of the three different MMS devices. The standard deviation values were initially analysed in the final 3D global models using the C2C (Cloud to Cloud) and C2M (Cloud to Mesh) distance calculation methods. Subsequently, the geometric differences were investigated through the extraction of horizontal profiles, and two more specific 2D analyses were carried out: the first inspecting the residual parameters calculated after the Helmert transformation from two sets of control points obtained from the profiles, followed by a local strain analysis. The study of the local deformation parameters allowed us to validate the results obtained and to identify the real limits of these survey instruments. The aim was to make a concrete contribution to the formalisation of an operative protocol for the morphological study of the city, exploiting the potential of these technologies to overcome the differences in scale and the gap between outdoor and indoor spaces

    Evaluation of Long-Range Mobile Mapping System (MMS) and Close-Range Photogrammetry for Deformation Monitoring. A Case Study of Cortes de PallĂĄs in Valencia (Spain)

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    none8openDi Stefano, Francesco; Cabrelles, Miriam; García-Asenjo, Luis; Lerma, José Luis; Malinverni, Eva Savina; Baselga, Sergio; Garrigues, Pascual; Pierdicca, RobertoDi Stefano, Francesco; Cabrelles, Miriam; García-Asenjo, Luis; Lerma, José Luis; Malinverni, Eva Savina; Baselga, Sergio; Garrigues, Pascual; Pierdicca, Robert

    Experiments on Surface Reconstruction for Partially Submerged Marine Structures

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    Over the past 10 years, significant scientific effort has been dedicated to the problem of three-dimensional (3-D) surface reconstruction for structural systems. However, the critical area of marine structures remains insufficiently studied. The research presented here focuses on the problem of 3-D surface reconstruction in the marine environment. This paper summarizes our hardware, software, and experimental contributions on surface reconstruction over the past few years (2008–2011). We propose the use of off-the-shelf sensors and a robotic platform to scan marine structures both above and below the waterline, and we develop a method and software system that uses the Ball Pivoting Algorithm (BPA) and the Poisson reconstruction algorithm to reconstruct 3-D surface models of marine structures from the scanned data. We have tested our hardware and software systems extensively in Singapore waters, including operating in rough waters, where water currents are around 1–2 m/s. We present results on construction of various 3-D models of marine structures, including slowly moving structures such as floating platforms, moving boats, and stationary jetties. Furthermore, the proposed surface reconstruction algorithm makes no use of any navigation sensor such as GPS, a Doppler velocity log, or an inertial navigation system.Singapore-MIT Alliance for Research and Technology. Center for Environmental Sensing and Modelin

    Geodetske mobilne mjerne metode za praćenje erozije obala rijeka

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    Rivers are relief features susceptible to change over time more than any other. Dynamic and intensity of those changes depend on a series of factors that have been a research topic for decades, all with the goal of predicting and/or preventing changes that have a negative effect on ecological and administrative systems alike. This is especially evident on big river systems. The topic of water course related erosion, being a phenomenon that changes the shape, position and flow of a water course, has not, to this day, been exhausted, primarily due to a myriad of factors directly and indirectly influencing the process. At the same time, determining the influence of each of those individual factors is not possible without the use of adequate measurement methods that allow fast acquisition of relevant data, based on witch correct conclusions can be made about individual processes. Emphasis on fast acquisition must be made here because rivers are dynamic bodies and the changes they cause are also relatively fast. Geodesy, including measuring techniques and methods that it uses, has experienced major development in the past decades. This has opened new possibilities for addressing those previously mentioned needs of river systems erosional processes and their research. Considering all of the above and supplementing with a fact that Danube is the largest and strongest river flowing through Croatia, it can be concluded that Danube is the one most interesting from the aspect of determining erosion phenomena frequency/intensity in Croatia. For acquiring relevant data in a relatively short time adequate survey methods need to be applied. Hence, Danube and its particularly interesting segments were selected for determining applicability of contactless mobile measurement solutions with the purpose of assessing those systems in determining and predicting erosional risks and cumulative rates.Rijeke su reljefni oblici koji su podloĆŸniji promjenama tokom vremena od bilo kojih drugih. Dinamika i intenzitet tih promjena ovisi o nizu faktora koji su desetljećima tema istraĆŸivanja sa ciljem predviđanja i/ili prevencije promjena koje imaju negativan utjecaj na kako ekoloĆĄke tako i administrativne sustave. To je posebno izraĆŸeno na velikim riječnim sustavima. Tema erozije pod utjecajem tekućih voda, kao fenomena koji mijenja oblik, poloĆŸaj i tok rijeka, nije, do danaĆĄnjeg dana, u potpunosti iscrpljena primarno zbog nebrojenih faktora koji direktno ili indirektno utječu na taj proces. Istovremeno, utvrđivanje utjecaja pojedinog faktora nije moguće bez upotrebe adekvatnih mjernih metoda, koje omogućavaju brzo prikupljanje relevantnih podataka na osnovu kojih je moguće donijeti ispravne zaključke o pojedinim procesima. Naglasak se stavlja na brzinu prikupljanja s obzirom da su rijeke dinamična tijela, ĆĄto znači da su i promijene, koje one posljedično uzrokuju, također, relativno brze. Geodezija, primarno mjerna tehnologija i metodologija koja se koristi, je u proteklim desetljećima doĆŸivjela značajan razvoj. Time su se otvorile nove mogućnosti za zadovoljavanje navedenih potreba pri istraĆŸivanju erozivnih procesa riječnih sustava. UzevĆĄi u obzir sve navedeno te dodajući podatak da je Dunav najveća i najsnaĆŸnija rijeka koja teče kroz Hrvatsku, moguće je zaključiti da je upravo ta rijeka najzanimljivija po pitanju utvrđivanja učestalosti/intenziteta erozivnog fenomena u Hrvatskoj. Za prikupljanje relevantnih podataka, u relativno kratkom vremenu, nuĆŸno je primijeniti adekvatne metode. Stoga je Dunav, odnosno njegovi najzanimljiviji dijelovi, odabran za utvrđivanje primjenjivosti bezkontaktnih mobilnih mjernih rjeĆĄenja sa svrhom ocjene takvih sustava za određivanje i predviđanje rizika od erozije te njenog iznosa
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