UAS close range remote sensing for mapping coastal environments

Παπακωνσταντίνου, Απόστολος; Topouzelis, Kostantinos; Doukari, Michaela

doi:10.1117/12.2278988

Cited by 12 publications

(10 citation statements)

References 7 publications

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“…The UAS-SfM methodology is used for 2D and 3D visualizations since it enables the development of high-resolution orthophoto maps, accurate digital surface models (DSM) and digital terrain models (DTM), and finally very detailed 3D models of the study area [19][20][21][22][23][24][25]. Furthermore, scientists are using UAS-SfM methodology for mapping and detecting; cultural sites, coastline changes, coastal erosion and the human pressure in the coastal zone [9,26,27].…”

Section: Introductionmentioning

confidence: 99%

Mapping Cultural Heritage in Coastal Areas with UAS: The Case Study of Lesvos Island

et al. 2019

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Dynamic processes in coastal zones and human activities in the coastal environment produce pressure on cultural heritage, especially in touristic places. Unmanned aerial systems (UAS) are used as an additional tool for monitoring cultural heritage sites in sensitive coastal areas. UASs provide low-cost accurate spatial data and high-resolution imagery products in various spatial and temporal scales. The use of UAS for mapping cultural heritage sites in the coastal zone is of increasing interest among scientists and archaeologists in terms of monitoring, documentation, mapping, and restoration. This study outlines the integration of UAS data acquisition and structure from motion (SfM) pipeline for the visualization of selected cultural heritage areas (ancient harbors) in the coastal zone. The UAS-SfM methodology produces very detailed orthophoto maps for mapping and detecting cultural heritage sites. Additionally, a metadata cataloging system has been developed in order to facilitate online searching operations for all products of the data acquisition, SfM pipeline, and cartographic processes. For this reason, a specific metadata profile was implemented, based on the European INSPIRE framework. As a result, datasets reusability and catalogs interoperability are promoted.

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Section: Introductionmentioning

confidence: 99%

Mapping Cultural Heritage in Coastal Areas with UAS: The Case Study of Lesvos Island

et al. 2019

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“…UAS are increasingly used in habitat mapping [7,12,[16][17][18]44], since they provide high-resolution data to inaccessible areas at a low cost and with high temporal repeatability [10,45,46]. The use of a multispectral camera with similar wavelengths to the Sentinel-2 satellite wavelengths was examined for the first time in the present study.…”

Section: Discussionmentioning

confidence: 99%

“…An overview of the followed methodological workflow is given below ( Figure 5). The methodology is organized into four steps: (i) data acquisition and creation of tc-RGB and multispectral orthomosaics using the UAS-SfM (structure-from-motion) framework [10,30], (ii) orthomosaics preprocessing, (iii) object-based image analysis, and (iv) accuracy assessment. After UAS and in situ data acquisition, the divers' photos passed quality control and were interpreted to define the class that is depicted.…”

Section: Methodological Workflowmentioning

confidence: 99%

“…These processes require multitemporal data, either from satellites or from unmanned aerial systems (UAS). The availability of very high-resolution orthomosaics presents increasing interest, as it provides to scientists and relevant stakeholders detailed information for understanding coastal dynamics and implementing environmental policies [6,[10][11][12][13]. However, the use of high-resolution orthomosaics created from UAS data is expected to improve mapping accuracy.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of True-Color and Multispectral Unmanned Aerial Systems Imagery for Marine Habitat Mapping Using Object-Based Image Analysis

Παπακωνσταντίνου¹,

Stamati²,

Topouzelis³

2020

Remote Sensing

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The use of unmanned aerial systems (UAS) over the past years has exploded due to their agility and ability to image an area with high-end products. UAS are a low-cost method for close remote sensing, giving scientists high-resolution data with limited deployment time, accessing even the most inaccessible areas. This study aims to produce marine habitat mapping by comparing the results produced from true-color RGB (tc-RGB) and multispectral high-resolution orthomosaics derived from UAS geodata using object-based image analysis (OBIA). The aerial data was acquired using two different types of sensors-one true-color RGB and one multispectral-both attached to a UAS, capturing images simultaneously. Additionally, divers' underwater images and echo sounder measurements were collected as in situ data. The produced orthomosaics were processed using three scenarios by applying different classifiers for the marine habitat classification. In the first and second scenario, the k-nearest neighbor (k-NN) and fuzzy rules were applied as classifiers, respectively. In the third scenario, fuzzy rules were applied in the echo sounder data to create samples for the classification process, and then the k-NN algorithm was used as the classifier. The in situ data collected were used as reference and training data. Additionally, these data were used for the calculation of the overall accuracy of the OBIA process in all scenarios. The classification results of the three scenarios were compared. Using tc-RGB instead of multispectral data provides better accuracy in detecting and classifying marine habitats when applying the k-NN as the classifier. In this case, the overall accuracy was 79%, and the Kappa index of agreement (KIA) was equal to 0.71, which illustrates the effectiveness of the proposed approach. The results showed that sub-decimeter resolution UAS data revealed the sub-bottom complexity to a large extent in relatively shallow areas as they provide accurate information that permits the habitat mapping in extreme detail. The produced habitat datasets are ideal as reference data for studying complex coastal environments using satellite imagery.

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“…For those reasons, as well as speed and low cost, SfM has been applied to the problem of acquiring shallow marine topography in coastal, estuarine, mudflat and intertidal zones where access is difficult and ground conditions frequently changing. In these settings both ground‐based (Pikelj, Ružić, Ilić, James, & Kordić, ) and airborne platforms including microlights (Brunier, Fleury, Anthony, Gardel, & Dussouillez, ) as well as the more common UAVs/drones (Jaud et al, ; Papakonstantinou, Topouzelis, & Doukari, ) to be used to acquire images. Other shallow marine settings are reviewed in the next section because they are not conducive to UAV/drone platform usage and must overcome a different set of problems; through water and underwater imaging.…”

Section: Applications In Aquatic Sciencesmentioning

confidence: 99%

Fluvial and aquatic applications of Structure from Motion photogrammetry and unmanned aerial vehicle/drone technology

Carrivick

Smith

2018

WIREs Water

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Structure from motion (SfM) has seen rapid uptake recently in the fluvial and aquatic sciences. This uptake is not least due to the widespread availability of cheap unmanned aerial vehicles/drones, which help mitigate the challenging terrain and deliver efficient and reproducible and high‐accuracy images and topographical data. These data can have unprecedented spatio‐temporal coverage and includes measurements of fluvial and aquatic topography, hydraulics, geomorphology and habitat quality. SfM data also offer novel quantification of underwater archeology, structures and aquatic organisms. Studies are shifting from proof‐of‐concepts in topographic survey to genuine applications including grain‐size mapping, bathymetric surveys, geomorphological mapping, vegetation mapping, restoration monitoring, habitat classification, geomorphological change detection and sediment transport path delineation. Integrating point cloud analyses and orthophoto mosaics with digital elevation models has been shown to be effective in providing novel process understanding of fluvial and aquatic systems. Underwater and through‐water studies are beginning to overcome problems of accessibility, visibility and image distortion. Archival photographs and video (both above‐ and under‐water) are being reprocessed using a SfM workflow to generate three‐dimensional surfaces and objects from historical surveys, thereby extending the time period over which change can be detected. Recently, a SfM workflow has been developed to model free water surfaces with clear potential for future exploitation in hydraulics, sediment transport and river bed evolution studies. Future applications of SfM could seek to exploit the daily repeat coverage of high‐resolution satellite images but must be mindful of the necessary investment in this development versus the increasing availability and coverage of spaceborne light detection and ranging. This article is categorized under: Water and Life > Methods Science of Water > Methods Water and Life > Nature of Freshwater Ecosystems

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UAS close range remote sensing for mapping coastal environments

Cited by 12 publications

References 7 publications

Mapping Cultural Heritage in Coastal Areas with UAS: The Case Study of Lesvos Island

Mapping Cultural Heritage in Coastal Areas with UAS: The Case Study of Lesvos Island

Comparison of True-Color and Multispectral Unmanned Aerial Systems Imagery for Marine Habitat Mapping Using Object-Based Image Analysis

Fluvial and aquatic applications of Structure from Motion photogrammetry and unmanned aerial vehicle/drone technology

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