How Image Acquisition Geometry of UAV Campaigns Affects the Derived Products and Their Accuracy in Areas with Complex Geomorphology

Kyriou, Aggeliki; Nikolakopoulos, Konstantinos G.; Koukouvelas, Ioannis

doi:10.3390/ijgi10060408

Cited by 32 publications

(30 citation statements)

References 49 publications

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“…Harwin et al [68] concluded that including oblique images is advised, as they can improve self-calibration of the bundle block adjustment and increase horizontal and vertical accuracy. Similar findings were presented by Kyriou et al [62]; they stated that the combination of nadir and oblique imagery can effectively be used for geomorphological mapping in areas with complex topography and steep slope (>60 • ), to increase the geometric accuracy of UAV data.…”

Section: Discussionsupporting

confidence: 82%

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Accuracy Assessment of UAV-Photogrammetric-Derived Products Using PPK and GCPs in Challenging Terrains: In Search of Optimized Rockfall Mapping

Žabota

Kobal

2021

Remote Sensing

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Unmanned aerial photogrammetric surveys are increasingly being used for mapping and studying natural hazards, such as rockfalls. Surveys using unmanned aerial vehicles (UAVs) can be performed in remote, hardly accessible, and dangerous areas, while the photogrammetric-derived products, with high spatial and temporal accuracy, can provide us with detailed information about phenomena under consideration. However, as photogrammetry commonly uses indirect georeferencing through bundle block adjustment (BBA) with ground control points (GCPs), data acquisition in the field is not only time-consuming and labor-intensive, but also extremely dangerous. Therefore, the main goal of this study was to investigate how accurate photogrammetric products can be produced by using BBA without GCPs and auxiliary data, namely using the coordinates X0, Y0 and Z0 of the camera perspective centers computed with PPK (Post-Processing Kinematic). To this end, orthomosaics and digital surface models (DSMs) were produced for three rockfall sites by using images acquired with a DJI Phantom 4 RTK and the two different BBA methods mentioned above (hereafter referred to as BBA_traditional and BBA_PPK). The accuracy of the products, in terms of the Root Mean Square Error (RMSE), was computed by using verification points (VPs). The accuracy of both BBA methods was also assessed. To test the differences between the georeferencing methods, two statistical test were used, namely a paired Student’s t-test, and a non-parametric Wilcoxon signed-rank. The results show that the accuracy of the BBA_PPK is inferior to that of BBA_traditional, with the total RMSE values for the three sites being 0.056, 0.066, and 0.305 m, respectively, compared to 0.019, 0.036 and 0.014 m obtained with BBA_traditional. The accuracies of the BBA methods are reflected in the accuracy of the orthomosaics, whose values for the BBA_PPK are 0.039, 0.043 and 0.157 m, respectively, against 0.029, 0.036 and 0.020 m obtained with the BBA_traditional. Concerning the DSM, those produced with the BBA_PPK method present accuracy values of 0.065, 0.072 and 0.261 m, respectively, against 0.038, 0.060 and 0.030 m obtained with the BBA_traditional. Even though that there are statistically significant differences between the georeferencing methods, one can state that the BBA_PPK presents a viable solution to map dangerous and exposed areas, such as rockfall transit and deposit areas, especially for applications at a regional level.

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Section: Discussionsupporting

confidence: 82%

“…The image overlaps were 80%. Pictures were taken at 45 • and 90 • angles, as the combination of oblique and nadir images contributes to a more accurate representation of terrain [62]. For planning the UAV mission, we used the DJI GS RTK application.…”

Section: Flight Planning and Acquisition Of Data With Uavmentioning

confidence: 99%

Accuracy Assessment of UAV-Photogrammetric-Derived Products Using PPK and GCPs in Challenging Terrains: In Search of Optimized Rockfall Mapping

Žabota

Kobal

2021

Remote Sensing

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“…This degree of accuracy may be more than sufficient for three-dimensional (3D) modeling projects or environmental monitoring that only requires relative accuracy. But for projects that usually require more accurately geo-referenced outputs, including land surveying, earthwork, topographic surveys, among others, a certain number of GCPs need to be deployed in the survey area [25]- [27]. The absolute or relative coordinates of these GCPs are commonly measured with GNSS RTK [28], [29], total stations [30], [31], among others.…”

Section: Introductionmentioning

confidence: 99%

“…GCPs need to be placed in suitable locations based on the image acquisition geometry to cope with terrain constraints [25], [26]. Following the acquisition of images from UAV surveys, the image coordinates of GCPs in corresponding photos must be obtained to play the role of GCPs in subsequent data processing and analyses, such as aerial triangulation and dense matching [42], [43].…”

Section: Introductionmentioning

confidence: 99%

An Automatic and Accurate Method for Marking Ground Control Points in Unmanned Aerial Vehicle Photogrammetry

Kong

Chen

Kang

et al. 2023

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Owing to the rapid development of unmanned aerial vehicle (UAV) technology and various photogrammetric software, UAV photogrammetry projects are becoming increasingly automated. However, marking ground control points (GCPs) in current UAV surveys still generally needs to be manually completed, which brings the problem of inefficiency and human error. Based on the characteristics of UAV photogrammetry, a novel type of circular coded target with its identification and decoding algorithm is proposed to realize an automatic and accurate approach for marking GCPs. UAV survey experiments validate the feasibility of the proposed method, which has comparative advantages in efficiency, robustness, and accuracy over traditional targets. Additionally, we conducted experiments to discuss the effects of projection size and viewing angle, number of coded bits, and environmental conditions on the proposed method. The results show that it can achieve robust identification and accurate positioning even under challenging conditions, and a smaller number of coded bits is recommended for better robustness.

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“…Mass wasting contributes immensely to landscape evolution of a planetary body not only through subaerial modifications, but even through subsurface and underwater modulations (e.g., [3][4][5][6][7][8][9]). In fact, mass movements are one of the most significant geomorphological processes molding the surface of our planet [10][11][12][13]. Interestingly, widely varying mass wasting features have also been identified on other planetary bodies such as the Moon (e.g., [14]), Mercury (e.g., [15]), Venus (e.g., [16]), Mars (e.g., [17][18][19][20][21]), and some outer Solar System satellites (e.g., [22]).…”

Section: Introductionmentioning

confidence: 99%

A Remote Sensing Perspective on Mass Wasting in Contrasting Planetary Environments: Cases of the Moon and Ceres

Sam

Bhardwaj

2022

Remote Sensing

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Mass wasting, as one of the most significant geomorphological processes, contributes immensely to planetary landscape evolution. The frequency and diversity of mass wasting features on any planetary body also put engineering constraints on its robotic exploration. Mass wasting on other Solar System bodies shares similar, although not identical, morphological characteristics with its terrestrial counterpart, indicating a possible common nature for their formation. Thus, planetary bodies with contrasting environmental conditions might help reveal the effects of the atmosphere, subsurface fluids, mass accumulation/precipitation, and seismicity on mass wasting, and vice versa. Their relative positions within our Solar System and the environmental and geophysical conditions on the Moon and the dwarf planet Ceres are not only extremely different from Earth’s but from each other too. Their smaller sizes coupled with the availability of global-scale remote sensing datasets make them ideal candidates to understand mass wasting processes in widely contrasting planetary environments. Through this concept article, we highlight several recent advances in and prospects of using remote sensing datasets to reveal unprecedented details on lunar and Cerean mass wasting processes. We start with briefly discussing several recent studies on mass wasting using Lunar Reconnaissance Orbiter Camera (LROC) data for the Moon and Dawn spacecraft data for Ceres. We further identify the prospects of available remote sensing data in advancing our understanding of mass wasting processes under reduced gravity and in a scant (or absent) atmosphere, and we conclude the article by suggesting future research directions.

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How Image Acquisition Geometry of UAV Campaigns Affects the Derived Products and Their Accuracy in Areas with Complex Geomorphology

Cited by 32 publications

References 49 publications

Accuracy Assessment of UAV-Photogrammetric-Derived Products Using PPK and GCPs in Challenging Terrains: In Search of Optimized Rockfall Mapping

Accuracy Assessment of UAV-Photogrammetric-Derived Products Using PPK and GCPs in Challenging Terrains: In Search of Optimized Rockfall Mapping

An Automatic and Accurate Method for Marking Ground Control Points in Unmanned Aerial Vehicle Photogrammetry

A Remote Sensing Perspective on Mass Wasting in Contrasting Planetary Environments: Cases of the Moon and Ceres

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