UAV BLOCK GEOREFERENCING AND CONTROL BY ON-BOARD GNSS DATA

Abstract. Unmanned Aerial Vehicles (UAV) are established platforms for photogrammetric surveys in remote areas. They are lightweight, easy to operate and can allow access to remote sites otherwise difficult (or impossible) to be surveyed with other techniques. Very good accuracy can be obtained also with low-cost UAV platforms as far as a reliable ground control is provided. However, placing ground control points (GCP) in these contexts is time consuming and requires accessibility that, in some cases, can be troublesome. RTK-capable UAV platforms are now available at reasonable costs and can overcome most of these problems, requiring just few (or none at all) GCP and still obtaining accurate results. The paper will present a set of experiments performed in cooperation with ARPA VdA (the Environmental Protection Agency of Valle d'Aosta region, Italy) on a test site in the Italian Alps using a Dji Phantom 4 RTK platform. Its goals are: a) compare accuracies obtainable with different calibration procedures (pre- or on-the-job/self-calibration); b) evaluate the accuracy improvements using different number of GCP when the site allows for it; and c) compare alternative positioning modes for camera projection centres determination, (Network RTK, RTK, Post Processing Kinematic and Single Point Positioning)

UAV BLOCK GEOREFERENCING and CONTROL by ON-BOARD GNSS DATA

Unmanned Aerial Vehicles (UAV) are established platforms for photogrammetric surveys in remote areas. They are lightweight, easy to operate and can allow access to remote sites otherwise difficult (or impossible) to be surveyed with other techniques. Very good accuracy can be obtained also with low-cost UAV platforms as far as a reliable ground control is provided. However, placing ground control points (GCP) in these contexts is time consuming and requires accessibility that, in some cases, can be troublesome. RTK-capable UAV platforms are now available at reasonable costs and can overcome most of these problems, requiring just few (or none at all) GCP and still obtaining accurate results. The paper will present a set of experiments performed in cooperation with ARPA VdA (the Environmental Protection Agency of Valle d'Aosta region, Italy) on a test site in the Italian Alps using a Dji Phantom 4 RTK platform. Its goals are: a) compare accuracies obtainable with different calibration procedures (pre- or on-the-job/self-calibration); b) evaluate the accuracy improvements using different number of GCP when the site allows for it; and c) compare alternative positioning modes for camera projection centres determination, (Network RTK, RTK, Post Processing Kinematic and Single Point Positioning)

A stake-out prototype system based on GNSS-RTK technology for implementing accurate vehicle reliability and performance tests

none4noThere are many car tests regulated by European and international standards and carried out on tracks to assess vehicle performance. The test preparation phase usually consists of placing road cones on the track with a specific configuration defined by the considered standard; this phase is performed by human operators using imprecise and slow methods, mainly due to the huge required distances. In this paper, a new geolocation stake-out system based on GNSS RTK technology has been realized and tested, supported by a Matlab-based software application to allow the user to quickly and precisely locate the on-track points on which to position the road cones. The realized stake-out system, innovative and very simple to use, produces negligible average errors (i.e. 2.4-2.9 cm) on the distance between the staked-out points according to the reference standards (distance percentage error 0.29-0.47%). Furthermore, the measured average angular error is also very low, in the range 0.04-0.18°. Finally, ISO 3888-1 and ISO 3888-2 test configurations were re-produced on the proving ground of the Porsche Technical Center by utilizing the realized stake-out system to perform a double lane-change manoeuvre on car prototypes.Special Issue "Electronic Systems and Energy Harvesting Methods for Automation, Mechatronics and Automotive 2021" Article Number: 4885openP. Visconti; F. Iaia, R. de Fazio, I. GiannoccaroVisconti, P.; Iaia, F.; de Fazio, R.; Giannoccaro, I

A Preliminary Analysis of Anthropogenic and Natural Impacts on a Volcanic Lake Ecosystem in Southern Italy by UAV-Based Monitoring

Lakes play an important role in providing various ecosystem services. However, stressors such as climate change, land use, or land-cover change threaten the ecological functions of lakes. National and international legislations address these threats and establish consistent, long-term monitoring schemes. Remote sensing techniques based on the use of Unmanned Aerial Vehicles (UAV) have recently been demonstrated to provide accurate and low-cost spatio-temporal views for the assessment of the ecological status of aquatic ecosystems and the identification of areas at risk of contamination. Few studies have been carried out so far on the employment of these tools in the monitoring of lakes. Therefore, high-resolution UAV surveys were used to analyse and evaluate natural and anthropogenic impacts on the habitat status of a volcanic lake in a protected area. Five UAV flights took place during a year-long cycle (November 2020 to November 2021) in a volcanic lake located in southern Italy. For each flight performance, an orthomosaic of georeferenced RGB images was obtained, and the different features of interest were monitored and quantified using automated processing in a GIS environment. The UAV images made it possible not only to estimate the flooded shores but also to detect the impact of human-made structures and infrastructures on the lagoon environment. It has been possible to observe how the rapid changes in lake-water level have led to the submersion of about 90.000 m(2) of terrain in winter, causing the fragmentation and degradation of habitats, while the connectivity of the natural ecosystem has been threatened by the presence of the road around the lake. The proposed methodology is rather simple and easily replicable by decision makers and local administrators and can be useful for choosing the best restoration interventions

Renewed e-learning oriented IHO Cat. B Hydrography Program (2020-) in Belgium

A study onhydrographic education in Belgium carried out a few years ago,pointed out a shortage in hydrographic training. Before the introduction of the new "Postgraduate in Hydrography", most hydrographic surveyors in Belgium work in one of the main Europeandredging companies where they received additional specific hydrographic surveying training.Therefore, in 2013, a 1-year English spoken curriculum degree of "Postgraduate in Hydrography" in Belgium was accredited by the IHO (International Hydrographic Organization). Then, in 2019, a renewed curriculum, including extensive e-learning facilities, was established.The program (Cat-B) is a cooperation between the Geography Department of Ghent University and the Institute for Hydrography of the Antwerp Maritime Academy, which is the hosting institute.The aim is to combine the compulsory theoretical courses with on-the-job training provided by partners in the industry to ensure maximum competences. All courses are lectured in English, and can be taken up over several years to facilitate part-time work. These procedures allow for a qualitative and professional, yet accessible program.The theoretical courses are taught on two different campuses, the campus of the Antwerp Maritime Academy (HZS) and a campus of Ghent University (UGent) based on the available expertise and infrastructure, thus ensuring the quality. As travel time between both cities is relatively fast (ca. 45 min. travel time by public or private transport) together with the boundary condition that both locations are never used on the same day, this presents no problems to the students. The navigation related topics are taught at the Maritime Academy while the geodesy/data management/geology and ICT related topics are provided by the Geography, Geology and Informatics Departments at Ghent University

NOVI PRISTUP PRAĆENJA POMAKA KLIZIŠTA POMOĆU BESPILOTNIH FOTOGRAMETRIJSKIH SUSTAVA

Landslides represent great dangers that can cause fatalities and huge property damage. To prevent or reduce all possible consequences that landslides cause, it is necessary to know the kinematics of the surface and undersurface sliding masses. Geodetic surveying techniques can be used for landslide monitoring and creating a kinematic model of the landslide. One of the most used surveying techniques for landslide monitoring is the photogrammetric survey by Unmanned Aerial System. The results of the photogrammetric survey are dense point clouds, digital terrain models, and digital orthomosaic maps, where landslide displacements can be determined by comparing these results in two measurement epochs. This paper presents a new data processing method with a novel approach for calculating landslide displacements based on Unmanned Aerial System photogrammetric survey data. The main advantage of the new method is that it does not require the production of dense point clouds, digital terrain models, or digital orthomosaic maps to determine displacements. The applicability and accuracy of the new method were tested in a test field with simulated displacements of known values within the range of 20-40 cm in various directions. The new method successfully determined these displacements with a 3D accuracy of ±1.3 cm.Klizišta predstavljaju velike opasnosti koje mogu uzrokovati katastrofalne ljudske žrtve te nanijeti veliku materijalnu štetu. Da bi se spriječile ili umanjile sve moguće posljedice koje klizišta prouzročuju, važno je poznavati kinematiku kretanja površinskih i podzemnih kliznih masa klizišta. Geodetske tehnike izmjere mogu se koristiti za potrebe praćenja te za izradu kinematičkoga modela klizišta. U današnje vrijeme jedna od najčešće korištenih geodetskih tehnika za potrebe praćenja klizišta jest fotogrametrijsko snimanje pomoću bespilotnih zrakoplovnih sustava. Rezultati su takvih snimanja gusti oblaci točaka, digitalni modeli terena te digitalne ortomozaik karte, a na temelju usporedbe tih rezultata u dvjema mjernim epohama mogu se odrediti pomaci klizišta. Ovaj rad predstavlja novu metodu obrade podataka s novim pristupom za određivanje pomaka klizišta na temelju podataka fotogrametrijskoga snimanja bespilotnim zrakoplovnim sustavima. Glavna je prednost nove metode u tome što ne zahtijeva izradu gustih oblaka točaka, digitalnih modela terena ili digitalnih ortomozaik karata za određivanje pomaka. Primjenjivost i točnost nove metode ispitane su na testnome polju sa simuliranim pomacima poznatih vrijednosti čiji su se iznosi kretali u rasponu od 20 do 40 cm u različitim smjerovima. Nova metoda uspješno je odredila te pomake s 3D točnošću od ±1,3 cm

Intensive archaeological survey at Piscina Torta: use of a low-cost RTK portable kit to materialise a UTM grid on the ground

We tested the use of a low-cost GPS RTK to set up a grid during the intensive archaeological survey of the Piscina Torta site, in the framework of the Salt and Power project of the University of Groningen. We also suggest not using a local grid but the WGS84 UTM grid and naming the single cells with the coordinates of one of its vertices. This would facilitate the use and exchange of the data (e.g. about the potsherds collected in the cell) among the scientific community