GNSS and Photogrammetric UAV Derived Data for Coastal Monitoring: A Case of Study in Emilia-Romagna, Italy

Vecchi, Enrica; Tavasci, Luca; Nigris, Nunzio De; Gandolfi, Stefano

doi:10.3390/jmse9111194

Cited by 11 publications

(10 citation statements)

References 31 publications

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“…The majority of errors did not exceed 4 pixels (8 cm) for the 3 surveys. Such a result is very similar to that found in [33,59,61,62], even though, in those surveys, UAV was used to identified elements on land instead of under water.…”

Section: Discussionsupporting

confidence: 78%

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Application of Unmanned Aerial Vehicles and Image Processing Techniques in Monitoring Underwater Coastal Protection Measures

et al. 2022

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A prerequisite for solving issues associated with surf zone variability, which affect human activity in coastal zones, is an accurate estimation of the effects of coastal protection methods. Therefore, performing frequent monitoring activities, especially when applying new nature-friendly coastal defense methods, is a major challenge. In this manuscript, we propose a pipeline for performing low-cost monitoring using RGB images, accessed by an unmanned aerial vehicle (UAV) and a four-level analysis architecture of an underwater object detection methodology. First, several color-based pre-processing activities were applied. Second, contrast-limited adaptive histogram equalization and the Hough transform methodology were used to automatically detect the underwater, circle-shaped elements of a hybrid coastal defense construction. An alternative pipeline was used to detect holes in the circle-shaped elements with an adaptive thresholding method; this pipeline was subsequently applied to the normalized images. Finally, the concatenation of the results from both the methods and the validation processes were performed. The results indicate that our automated monitoring tool works for RGB images captured by a low-cost consumer UAV. The experimental results showed that our pipeline achieved an average error of four pixels in the test set.

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Section: Discussionsupporting

confidence: 78%

“…It has been proved that UAV photogrammetry is useful when decimeter-level accuracy is required. Different surveys report photogrammetric model accuracy values on sub-centimeter values, respectively, for the horizontal component [59,60]. The accuracy we found in identification of underwater objects by UAV was very similar.…”

Section: Discussionmentioning

confidence: 51%

Application of Unmanned Aerial Vehicles and Image Processing Techniques in Monitoring Underwater Coastal Protection Measures

et al. 2022

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“…Following field data collection (UAS-based image acquisitions and GNSS measurements) the well-established photogrammetric SfM-MVS workflow was performed. The imagery acquired at the study site was processed using Agisoft Metashape Professional (version 1.7.4-Windows 64 bit), a commercial SfMphotogrammetry package commonly used by the research community for a range of study contexts (Rossi et al, 2017;Moyano et al, 2020;Vecchi et al, 2021). This photogrammetric package allows to generate a range of digital outputs (e.g., dense point cloud, rasterized DTMs, orthomosaics, etc.)…”

Section: Data Processing and Comparisonsmentioning

confidence: 99%

Quick bathymetry mapping of a Roman archaeological site using RTK UAS-based photogrammetry

et al. 2023

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Recent technological advances are leading numerous researchers and professional users to the adoption of photogrammetric products for a wide range of geoscientific applications. Especially, drone-based Structure-from-Motion (SfM) photogrammetry is often applied as a high-resolution topographic modelling technique with advantages in terms of time and cost when compared to traditional surveying approaches. The aim of this work, carried out within the GeoArchaeo Sites Project, is to investigate the adaptability of drone-based surveys, even with a targetless approach, and to estimate bathymetrical accuracies in shallow waters. The approach was applied on an underwater site to show the potential for the digitalization and monitoring of an archaeological coastal geosystem in central Italy. Specifically, this work has compared the photogrammetric surveying capability of two drones including a Phantom 4 RTK (‘P4RTK’) and a low-cost Mavic Mini 2 (‘MM2’) and an Olympus TG-6 (underwater camera) for a site submerged with a maximum depth of ∼1.6 m. The assessment of the drone SfM-based products was performed through area-based and point-wise comparisons. Specifically, the area-based were assessed through an underwater photogrammetric survey obtained by acquiring images by an operator snorkeling along a portion of the site of interest. The point-wise comparison was performed using data acquired with a Global Navigation Satellite System (GNSS). This study demonstrates that coupling SfM-photogrammetry and UAS-based surveys have potential to define submerged topography. In particular, the imagery acquired with the P4RTK survey can produce dense 3D models of the underwater surface with high resolution (about 0.02 m) and bathymetric measurements with a vertical accuracy ranging between 0.06 and 0.29 m for the area-based and point-wise analysis, respectively. Thus, the approach adopted and tested involving the use of a P4RTK has the potential to reduce constraints and limitations in terms of GCPs distribution and measurement. Also, with such an approach the need for qualified operators for underwater photogrammetric workflow can be avoided.

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“…The use of global navigation satellite systems (GNSSs) in the agricultural field dates back to the 90s, with the development of farm machines equipped with GNSS receivers. However, the use of GNSS instruments to acquire field measurements cannot ensure high-density datasets without resulting in very time-consuming and expensive surveys [10]. Therefore, in this context, they are commonly employed as a support for other techniques.…”

Section: Introductionmentioning

confidence: 99%

UAV Photogrammetric Surveys for Tree Height Estimation

Vacca,

Vecchi

2024

Drones

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In the context of precision agriculture (PA), geomatic surveys exploiting UAV (unmanned aerial vehicle) platforms allow the dimensional characterization of trees. This paper focuses on the use of low-cost UAV photogrammetry to estimate tree height, as part of a project for the phytoremediation of contaminated soils. Two study areas with different characteristics in terms of mean tree height (5 m; 0.7 m) are chosen to test the procedure even in a challenging context. Three campaigns are performed in an olive grove (Area 1) at different flying altitudes (30 m, 40 m, and 50 m), and one UAV flight is available for Area 2 (42 m of altitude), where three species are present: oleander, lentisk, and poplar. The workflow involves the elaboration of the UAV point clouds through the SfM (structure from motion) approach, digital surface models (DSMs), vegetation filtering, and a GIS-based analysis to obtain canopy height models (CHMs) for height extraction based on a local maxima approach. UAV-derived heights are compared with in-field measurements, and promising results are obtained for Area 1, confirming the applicability of the procedure for tree height extraction, while the application in Area 2 (shorter tree seedlings) is more problematic.

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GNSS and Photogrammetric UAV Derived Data for Coastal Monitoring: A Case of Study in Emilia-Romagna, Italy

Cited by 11 publications

References 31 publications

Application of Unmanned Aerial Vehicles and Image Processing Techniques in Monitoring Underwater Coastal Protection Measures

Application of Unmanned Aerial Vehicles and Image Processing Techniques in Monitoring Underwater Coastal Protection Measures

Quick bathymetry mapping of a Roman archaeological site using RTK UAS-based photogrammetry

UAV Photogrammetric Surveys for Tree Height Estimation

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