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Three raster-based (RB) and one point cloud-based (PCB) algorithms were tested to segment individual Aleppo pine trees and extract their tree height (H) and crown diameter (CD) using two types of point clouds generated from two different techniques: (1) Low-Density (≈1.5 points/m2) Airborne Laser Scanning (LD-ALS) and (2) photogrammetry based on high-resolution unmanned aerial vehicle (UAV) images. Through intensive experiments, it was concluded that the tested RB algorithms performed best in the case of UAV point clouds (F1-score > 80.57%, H Pearson's r > 0.97, and CD Pearson´s r > 0.73), while the PCB algorithm yielded the best results when working with LD-ALS point clouds (F1-score = 89.51%, H Pearson´s r = 0.94, and CD Pearson´s r = 0.57). The best set of algorithm parameters was applied to all plots, i.e., it was not optimized for each plot, in order to develop an automatic pipeline for mapping large areas of Mediterranean forests. In this case, tree detection and height estimation showed good results for both UAV and LD-ALS (F1-score > 85% and >76%, and H Pearson´s r > 0.96 and >0.93, respectively). However, very poor results were found when estimating crown diameter (CD Pearson´s r around 0.20 for both approaches). [ABSTRACT FROM AUTHOR]

Underground coal mining induces surface subsidence, leading to disasters such as damage to buildings and infrastructure, landslides, and surface water accumulation. Preventing and controlling disasters in subsidence areas and reutilizing land depend on understanding subsidence regularity and obtaining surface subsidence monitoring data. These data are crucial for the reutilization of regional land resources and disaster prevention and control. Subsidence hazards are also a key constraint to mine development. Recently, with the rapid advancement of UAV technology, the use of UAV photogrammetry for surface subsidence monitoring has become a significant trend in this field. The periodic imagery data quickly acquired by UAV are used to construct DEM through point cloud filtering. Then, surface subsidence information is obtained by differencing DEM from different periods. However, due to the accuracy limitations inherent in UAV photogrammetry, the subsidence data obtained through this method are characterized by errors, making it challenging to achieve high-precision ground surface subsidence monitoring. Therefore, this paper proposes a spatial domain filtering algorithm for UAV photogrammetry combined with surface deformation caused by coal mining based on the surface subsidence induced by coal mining and combined with the characteristics of the surface change. This algorithm significantly reduces random error in the differential DEM, achieving high-precision ground subsidence monitoring using UAV. Simulation and field test results show that the surface subsidence elevation errors obtained in the simulation tests are reduced by more than 50% compared to conventional methods. In field tests, this method reduced surface subsidence elevation errors by 39%. The monitoring error for surface subsidence was as low as 8 mm compared to leveling survey data. This method offers a new technical pathway for high-precision surface subsidence monitoring in mining areas using UAV photogrammetry. [ABSTRACT FROM AUTHOR]

The Weining-Shuicheng Fault (WSF) is a northwest-southeast trending fault in the southwest of the South China Block (SCB), which is an important component of the Yadu-Ziyun Fault Zone. The study of its activity is of great significance for analyzing the boundary role of the Daliangshan secondary block on the SCB. This paper derived the following results through field investigations, high-precision remote sensing image interpretation, UAV photogrammetry, trenching technique, and AMS 14C age. The WSF is northwest-trending with a sinistral strike-slip. It has a total displacement of about 2.5–3.2 km, which is equivalent to that of the southern section of the Daliangshan Fault. There are visible landforms such as fault scarps and fault valleys along the WSF, which control the development of the Caohai Basin. The gully near Weining Airport was caused by left lateral dislocations with a displacement of about 4 m. The Tashan trench revealed two branching faults, cutting the latest strata formed during about 13,000 BC. The Wangjiachong trench revealed five branching faults, cutting the latest strata formed during about 20,000 BC. The northern section of the WSF is flower-shaped tectonic features near the plane and activated in the Late Pleistocene.

Accurately recognizing the structural planes of high rock slopes and obtaining occurrence information are important prerequisites for conducting slope stability analysis. Unmanned aerial vehicle photogrammetry technology provides the possibility to solve the problem of accurate surveying of high slope structural planes. But it lacks efficient and accurate image post-processing methods. The existing research has not considered the uncertainty of structural plane occurrence information features, resulting in poor accuracy and efficiency in structural plane recognition. In order to solve the above problems, taking a high slope of an open-pit mine in Nanchang City, Jiangxi Province as the research background, an integrated method for recognizing structural planes and collecting occurrence information by integrating unmanned aerial vehicle photography, post-processing algorithms, and statistical analysis is proposed. Firstly, the method obtains surface images of the slope using the Phantom 4 Pro V2.0 unmanned aerial vehicle. Secondly, the method uses Context Capture software for processing, and the high-density 3D point cloud data is obtained. Secondly, the K-nearest neighbor (KNN) algorithm is used to determine the number of nearest neighbor points to construct a set of similar points. The density-based spatial clustering of applications with noise (DBSCAN) algorithm is used for clustering analysis to recognize slope structural planes, obtain structural plane occurrence information, and perform statistical feature analysis. Finally, comparative verification is conducted through on-site survey data. The results show that this method can quickly obtain complete high-density point cloud data, accurately and efficiently recognize most structural planes of high rock slopes. The recognition results are basically consistent with the actual situation of slope engineering sites. This method can obtain information on the number, occurrence, and statistical features of high slope structural planes. The probability distribution of most structural plane dip angles and inclinations fits well with the measured data, providing an important data source for the construction of high slope fracture network models and stability analysis.

The Twenty Eyes Aqueduct stands as a monumental hydraulic structure with a rich history spanning several centuries, poised to be designated as a heritage asset of cultural interest (Bien de Interés Cultural, BIC). This infrastructure poses a significant challenge for structural simulation, given the heterogeneous nature of its materials, geometric irregularities and challenging accessibility. Recent advancements in UAV photogrammetry, coupled with the evolution of BIM and the computational capabilities of modern computers for calculating FEM, present a methodology for simulating the behaviour of structures under applied loads. This approach enables us to address the tasks of reconstruction, protection and conservation of our heritage with unprecedented precision, speed and perspective. In this study, the innovative Cloud-to-BIM-to-FEM methodology is applied, which is capable of converting BIM models generated from point clouds into FEM. Obtaining the point cloud was possible using UAV photogrammetry, during which a 3D survey of the current state of the aqueduct was conducted. The point cloud obtained served as the basis for generating an HBIM that accurately represents the geometry of the aqueduct (Cloud-to-BIM). The HBIM was then transformed into a FEM model that respects the monument’s singularity without excessive geometric simplifications (BIM-to-FEM). Finally, various considerations were deduced regarding the stability of the aqueduct and its structural behaviour by applying loads such as wind and earthquake.

The introduction of unmanned aerial vehicles (UAVs) and their deployment as tools for terrain information gathering has prompted discussions regarding the quality of the resulting products and the potential for their extended applications in geomatics. This study specifically focuses on evaluating the utilization and capabilities of UAV photogrammetry in generating topographic maps, with a primary emphasis on assessing the accuracy of these maps. An area of approximately 2.65 km2 of the New Administrative Capital in Cairo, Egypt, was captured using a DJI M300 RTK drone. Agisoft Metashape and Pix4Dmapper software were used to process digital images to produce orthophotos and digital surface models. The precision of direct geo-referencing was evaluated by utilizing common tie points extracted by the user and the onboard GPS camera positions recorded during flight. Horizontal and vertical RMSEs were measured at 0.069 m and 0.593 m for Pix4Dmapper and 0.062 m and 0.548 m for Agisoft Metashape, respectively. Notably, direct geo-referencing exhibited lower accuracy, particularly in the vertical dimension. In the 7-GCP scenario, when combined with indirect geo-referencing, both software packages achieved the highest accuracy, with radial RMSEs of 0.023 m and 0.054 m and vertical RMSEs of 0.038 m and 0.052 m, respectively, corresponding to a pixel size of 1.7–2.2 times the ground sampling distance (GSD). In summary, this study affirms the efficacy of utilizing UAV photogrammetry in creating digital maps, orthophotos, contour lines, digital terrain models, digital surface models, and line maps, all aligning with globally recognized standards. [ABSTRACT FROM AUTHOR]

The rationality of rockfall path analysis results is closely related to the resolution of the slope shape model. With the emergence of unmanned aerial vehicle (UAV) photogrammetry technology, which is suitable for engineering geological surveys, the modeling resolution for unstable rock slopes has gradually increased. In this paper, the process of constructing a model of unstable rock slopes based on UAV photogrammetry is improved. A method to obtain the geometric parameters of unstable rock masses by using the model is proposed. The movement characteristics required for rockfall analysis are summarized. Based on the analytical results of rockfalls, a method for setting up passive protective nets is suggested. A quantitative evaluation method is proposed for the protective effect of each protective scheme. Through a practical engineering case, two passive protective schemes (the original design and the optimized design based on the proposed method) are compared and evaluated by numerical simulation, and the actual site layout scheme is more similar to the optimized design scheme. The results show that the proposed method has a positive effect on the design and improvement of protective nets. [ABSTRACT FROM AUTHOR]

In this study, we utilized unmanned aerial vehicle (UAV) and high-precision 3D light detection and ranging (LiDAR) scanning to collect data before and after an earthquake-resistant behavior test on a reinforced concrete hybrid frame. We analyzed the deformation of the hybrid frame before and after the test and determined the specific deformation, scale, and change rule. The UAV image data was transformed into a 3D true-color model using the structure from motion (SfM) algorithm. Additionally, the 3D Delaunay surface reconstruction algorithm was used to create a 3D point cloud model and Rodriguez matrix, which are then used to align the two-phase model. Subsequently, a comparison was made in three dimensions between the distribution of the hybrid frame's photographic and 3D point cloud models before and after undergoing earthquake-resistant behavior tests. This method allows for a precise analysis of the local deformation degree of the hybrid frame structure compared with the sensors. While the sensors can only analyze internal structural changes, this method provides results for both local and surface deformation degrees, which are not available in the sensor data. The comprehensive experimental comparison results demonstrate that the reinforced concrete hybrid frame structure had a collective rightward displacement before and after the earthquake-resistant behavior test. Moreover, nodes and edges exhibited more significant deformation, and the test resulted in a more stable overall framework. [ABSTRACT FROM AUTHOR]

The NW-SE-trending dextral strike-slip faults on the north side of the Tian Shan, e.g., the Karatau fault, Talas–Fergana fault, Dzhalair–Naiman fault, Aktas fault, Dzhungarian fault, and Chingiz fault, play an important role in accommodating crustal shortening. The classic viewpoint is that these strike-slip faults are an adjustment product caused by the difference in the crustal shortening from west to east. Another viewpoint attributes the dextral strike-slip fault to large-scale sinistral shearing. The Alakol Lake fault is a typical dextral strike-slip fault in the north Tian Shan that has not been reported. It is situated along the northern margin of the Dzhungarian gate, stretching for roughly 150 km from Lake Ebinur to Lake Alakol. Our team utilized aerial photographs, satellite stereoimagery, and field observations to map the spatial distribution of the Alakol Lake fault. Our findings provided evidence supporting the assertion that the fault is a dextral strike-slip fault. In reference to its spatial distribution, the Lake Alakol is situated in a pull-apart basin that lies between two major dextral strike-slip fault faults: the Chingiz and Dzhungarian faults. The Alakol Lake fault serves as a connecting structure for these two faults, resulting in the formation of a mega NW-SE dextral strike-slip fault zone. According to our analysis of the dating samples taken from the alluvial fan, as well as our measurement of the displacement of the riser and gully, it appears that the Alakol Lake fault has a dextral strike-slip rate of 0.8–1.2 mm/a (closer to 1.2 mm/a). The strike-slip rate of the Alakol Lake fault is comparatively higher than that of the Chingiz fault in the northern region (~0.7 mm/a) but slower than that of the Dzhungarian fault in the southern region (3.2–5 mm/a). The Chingiz–Alakol–Dzhungarian fault zone shows a gradual decrease in deformation towards the interior of the Kazakhstan platform. [ABSTRACT FROM AUTHOR]

The use of UAV represents a very useful tool for rock mass characterization, particularly in large, unsafe, and not accessible areas characterized by a complex geometry. This investigation was mainly focused on mapping discontinuities and characterizing rock masses using UAV photogrammetry, machine learning, including different algorithms, and intact rock laboratory analyses, respectively. To this aim different outcrops from those described as a part of the basement of the Acoculco Caldera Complex, composed by a series of folded limestones were selected. The results indicate that geomechanical and physical properties, together with outcrop information are very important to assign suitable properties to large rock units. In turn, the great number of plots of discontinuity orientation extracted from the 3D point cloud data by the used of our code written in python language allowed to easily identify the presence of a total of seven discontinuity sets, some of them related to the bedding sequence and some others related to shear and tensile stress due to folding. Highlights: • Discontinuity orientation extracted from the 3D point cloud data, allowed to easily identify the presence of discontinuity sets. • A detailed characterization of intact rock and discontinuities is presented and discussed. • This manuscript is accompanied by a code written in python programming language, placed in a public repository. • Detailed characterization of the properties of the rock mass is necessary to build different conceptual models in the area. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Geological surveying prior to site selection is a crucial component to ensure the smooth implementation of large-scale infrastructure projects. To explore cost-effective and practical geological surveying techniques, a mining area in South Central China was taken as an example and unmanned aerial vehicles (UAVs) equipped with high-resolution cameras and with high-density grid imaging mode were utilized to capture images and achieve 3D reconstruction of the study area. After generating a digital elevation model from the point cloud model, relevant geological information was extracted to conduct preliminary assessment of potential geological risks. The results indicate that UAV-based aerial survey significantly improves the efficiency of geological surveying compared to manual techniques, providing a clear and accurate representation of the actual conditions in the test area. The high-density grid imaging mode proves to be convenient for this kind of missions, and the integrated analysis of 3D models, point cloud models, and DEM (digital elevation models) exhibits a strong correlation with reality. The findings of this study offer novel insights for geological reconnaissance practices. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle light detection and ranging (UAV‐lidar) and unmanned aerial vehicle (UAV) photogrammetry are currently commonly used surface monitoring technologies. Previous studies have used the two technologies interchangeably and ignored their correlation, or only compared them on a single product. However, there are few quantitative assessments of the differences between these two techniques in monitoring surface deformation and prediction of their application prospects. Therefore, the paper compared the differences between the digital elevation model (DEM) and subsidence basins obtained by the two techniques using Gaussian analysis. The results indicate that the surface DEMs obtained by both the techniques exhibit a high degree of similarity. The statistical analysis of the difference values in the z direction between the two DEMs follows a Gaussian distribution with a standard deviation of less than 0.36 m. When comparing the surface subsidence values monitored by the two techniques, it was found that UAV‐lidar was more sensitive to small‐scale deformation, with a difference range of 0.23–0.44 m compared to photogrammetry. The conclusion provides valuable information regarding the utilisation of multisource monitoring data. [ABSTRACT FROM AUTHOR]

For several years, photogrammetric surveys are quite often applied for surveying cultural heritage. For a detailed and accurate result, it is indispensable that the calculated point cloud represents the original geometry of the building in high quality, with vertical and horizontal structures in the same manner. Whereas many published papers in the field of digital heritage documentation are dealing with creating such models or using photogrammetric data for damage detection, only a few papers are investigating the crucial fact of accuracy and how it can be influenced by the used camera resolution. We want to present a case study, in which we compare the photogrammetric point cloud of a normal consumer drone with a high-end device. Beside the actual survey results showing the details of a Romanesque church, a statistical calculation of deviation is shown. It becomes evident that there is only a difference within some millimetres between the corresponding point clouds in most parts of the monument. Hence, it can be stated that, for most applications in heritage protection, affordable consumer unmanned aerial vehicles (UAVs) are sufficient. Only if faint details have to be resolved will a better resolution of the mounted camera be required. [ABSTRACT FROM AUTHOR]

Following a complementary non-invasive analysis including satellite and aerial imagery, as well as UAV-based photogrammetric and LiDAR surveys, this paper presents and discusses the Roman military evidence identified at Alto do Golado (São Pedro do Sul) and Modedufe (Lamego). Though the archaeological remains of these sites have been partly noticed before, undetected relevant aspects resulted in misinterpretations, which are now reassessed in this study. Constituting the first known evidence of the Roman army in the region located between the Vouga and Douro rivers, further analysis of computed GIS models resulted in some hypotheses regarding mobility, visibility and territorial control. Ultimately, this paper also stresses the importance and the need for additional, invasive archaeological research to validate these hypotheses and, consequently, contribute to a better understanding not only of the sites here discussed but also of the Roman military presence in Western Iberia.

Digital Elevation Model (DEM) errors tend to be spatially correlated, inevitably affecting DEM-based topographic change detection. Traditional topographic change detection methods often ignore the spatial distribution of the DEM error. This paper aims to develop a workflow that considers the spatial autocorrelation of the error in topographic change detection. Firstly, the DEM of Difference (DoD) is obtained from two-period DEMs, and the Monte Carlo method is employed to evaluate the Spatially Distributed Errors (SDE) in DEMs. Secondly, DoD errors are calculated by propagation based on spatially distributed DEM errors. At the same time, its spatial distribution is quantified using the semi-variance function. Finally, topographic changes (erosion, deposition, and net changes) are calculated based on the spatial distribution analysis and significance detection. The results in two small catchments indicate that DEM errors are spatially correlated, increasing the volume calculation errors. However, using Standard Deviation of Errors (SDE) instead of Root Mean Square Error (RMSE) can effectively reduce the sensitivity of the detection results in the significance threshold. When the significance threshold increases from 68% to 95%, the observations loss using the spatially distributed error is 4.67% −6.92% lower than that using the RMSE. The level of detection has little impact on the net topographic change and significantly influences gross erosion and deposition. In particular, the use of level of detection can effectively reduce the misclassification of erosion or deposition in stable topography areas. The proposed method can be effectively utilized in various applications like surface deformation monitoring, erosion monitoring, and sediment transport assessment.

Terraced slopes are widely used in the Loess Plateau to control gully erosion, yet their potential to induce new erosion patterns remains overlooked. Here we used unmanned aerial vehicle (UAV) photogrammetry to obtain centimeter‐resolution digital surface models (DSMs) and derived hydrological networks, slopes, aspects, and curvatures of the terraced slopes. Our analysis reveals terraces disrupted natural water pathways, spurring new rill formations during each rainy season—a process neglected by models. Intriguingly, despite gentler gradients, terraced slopes exhibited higher erosion rates than steeper gullies, with widespread rills on terrace ridges. Vegetation‐induced deposition surpassed erosion by 1.52 times, but moisture evaporation on sunny slopes limited plant growth and enhanced erosion. We propose targeted strategies tailored to these erosion mechanisms, including terrace redesign, runoff diversion, slope strengthening, and suitable vegetation, advancing sustainable land management. However, this study faces limitations due to the reliance on drone photogrammetry, which may be influenced by environmental factors like varying solar angles and vegetation growth, and the lack of extensive field validation to support the UAV‐derived data. Our study spotlights drone photogrammetry's potential for elucidating complex erosion dynamics on terraced slopes. [ABSTRACT FROM AUTHOR]

The present study proposes a preliminary analysis method for rock mass joint acquisition, analysis, and slope stability assessment based on unmanned aerial vehicle (UAV) photogrammetry to extract the joint surface attitude in Geographic Information Systems (GIS). The method effectively solves the difficulties associated with the above issues. By combining terrain-following photogrammetry (TFP) and perpendicular and slope surface photogrammetry (PSSP), the three-dimensional (3D) information can be efficiently obtained along the slope characteristics' surface, which avoids the information loss involved in traditional single-lens aerial photography and the information redundancy of the five-eye aerial photography. Then, a semi-automatic geoprocessing tool was developed within the ArcGIS Pro 3.0 environment, using Python for the extraction of joint surfaces. Multi-point fitting was used to calculate the joint surface attitude. The corresponding attitude symbols are generated at the same time. Finally, the joint surface attitude information is used to perform stereographic projection and kinematic analysis. The former can determine the dominant joint group, and the latter can obtain the probability of four types of failure, including planar sliding, wedge sliding, flexural toppling, and direct toppling. The integrated stability evaluation method studied in this paper, which combines a 3D interpretation of UAV and GIS stereographic projection statistical analysis, has the advantages of being efficient and user-friendly, and requires minimal prior knowledge. The results can aid in the geological surveys of slopes and guide engineering practices. [ABSTRACT FROM AUTHOR]

UAV photogrammetry is a crucial technique for conserving cultural heritage sites, particularly oblique images. However, studies on this method are limited. The Jewish Neighbourhood in Akre, with its significant historical and architectural value, needs urgent documentation to prevent further deformation. This article aims to present the methods and techniques of data acquisition and processing to document the traditional terrace form of the Jewish Neighbourhood. UAV was used to capture 337 images at an altitude of 40 meters with a tilted camera angle of 45 degrees. Agisoft Metashape photogrammetry software was used to process the images and produce a 3D digital surface model of the buildings, quantitative and qualitative methods were carried out to assess the accuracy of the deliverables. In addition, Global Mapper and ArcGIS software were used to drive more documentation details that would serve to set the required operational guidelines to preserve the traditional terrace form of this site. Results show that the accuracy of the produced 3D model is high and further proves that UAV photogrammetry using oblique images is an effective technique for documenting such complex historical sites. [ABSTRACT FROM AUTHOR]

Nature-based solutions have gained popularity as an approach to tackling hydro-meteorological hazards (HMHs) in both urban and rural settings. Despite this popularity, challenges persist regarding the evidence base for their effectiveness and data scarcity at the feature or site scale. Flood modelling is a common approach to quantifying the effectiveness of NbS; however, the accuracy of these models heavily depends on the accuracy of the DEM, land cover, and hydraulic/hydrological data utilised. Remote and rural settings often face data scarcity due to the challenging nature of data collection, and insufficient funding for monitoring. Additionally, NbS features vary in size and scale, with many being small (

In recent years, unmanned aerial vehicles (UAVs) have become increasingly important as a tool for quickly collecting high-resolution (spatial and spectral) imagery of the Earth's surface. The final products are highly dependent on the choice of values for various parameters in flight planning, the type of sensors, and the processing of the data. In this paper ground control points (GCPs) were first measured using the Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) method, and then due to the low height accuracy of the GNSS RTK method all points were measured using a detailed leveling method. This study aims to provide a basic assessment of quality, including four main aspects: (1) the difference between an RGB sensor and a five-band multispectral sensor on accuracy and the amount of data, (2) the impact of the number of GCPs on the accuracy of the final products, (3) the impact of different altitudes and cross flight strips, and (4) the accuracy analysis of multi-altitude models. The results suggest that the type of sensor, flight configuration, and GCP setup strongly affect the quality and quantity of the final product data while creating a multi-altitude model does not result in the expected quality of data. With its unique combination of sensors and parameters, the results and recommendations presented in this paper can assist professionals and researchers in their future work.

Urban storm drainage is essential for the large part of the population living in cities with torrential rains to protect public urban infrastructure, private property, and human lives from flooding. The most important design parameter for urban storm drainage is the flow discharge, which is normally calculated with the area, runoff coefficient, and rainfall intensity depending on basin delineation. This requires highly accurate topographic information on the urbanized terrain that digital elevation models sometimes do not meet due to the lack of resolution. This study proposes criteria for delineating urban basins considering urbanization without requiring the usual topographic surveys. The proposed basin delineation is based on a high-resolution digital elevation model obtained from an unmanned aerial vehicle (UAV) and field verification of flow directions. As a result, the delineation of two urban basins was obtained: an urban basin within an area that drains exclusively to a sinkhole and another basin that additionally drains out through other points of the divide. The latter basin does not comply with the traditional concept of a hydrological basin because it has more than one outlet. In addition, this basin has an area that is 38% of the total area draining into the sinkhole. HIGHLIGHTS Methodology to delineate urban basins based on UAV photogrammetry.; Geospatial and surface flow direction analysis for urban basin delineation.; More precise urban basin delineation that considers the layout of streets.; Less expensive high-resolution topography to delineate urban basins.;

Constructing high-precision subsidence basins is of paramount importance for mining subsidence monitoring. Traditional unmanned aerial vehicle (UAV) photogrammetry techniques typically construct subsidence basins by directly differencing digital elevation models (DEMs) from different monitoring periods. However, this method often neglects the influence of horizontal displacement on the accuracy of the subsidence basin. Taking a mining area in Ordos, Inner Mongolia, as an example, this study employed the normalized cross-correlation (NCC) matching algorithm to extract horizontal displacement information between two epochs of a digital orthophoto map (DOM) and subsequently corrected the horizontal position of the second-epoch DEM. This ensured that the planar positions of ground feature points remained consistent in the DEM before and after subsidence. Based on this, the vertical displacement in the subsidence area (the subsidence basin) was obtained via DEM differencing, and the parameters of the post-correction subsidence basin were inverted using the probability integral method (PIM). The experimental results indicate that (1) the horizontal displacement was influenced by the gully topography, causing the displacement within the working face to be segmented on both sides of the gully; (2) the influence of the terrain on the subsidence basin was significantly reduced after correction; (3) the post-correction surface subsidence curve was smoother than the pre-correction curve, with abrupt error effects markedly diminished; (4) the accuracy of the post-correction subsidence basin increased by 43.12% compared with the total station data; and (5) comparing the measured horizontal displacement curve with that derived using the probability integral method revealed that the horizontal displacement on the side of an old goaf adjacent to the newly excavated working face shifted toward the advancing direction of the new working face as mining progressed. This study provides a novel approach and insights for using low-cost UAVs to construct high-precision subsidence basins.

Introduction: Reservoir landslides undergo large deformations during the early stages of impoundment and maintain long-term persistent deformations during the operational period of the reservoir. The management of reservoir landslides mostly focuses on the early identification, risk assessment during the large deformations, and long-sequence monitoring during long-term persistent deformations, which requires sufficient continuity and integrity of the landslide monitoring data. Methods: Taking the Wulipo (WLP) landslide in Baihetan Reservoir as example, this paper proposes a reservoir landslide monitoring method that integrates field survey, unmanned aerial vehicle (UAV) photogrammetry and global navigation satellite system (GNSS) monitoring, which can effectively eliminate the practical monitoring gaps between multiple monitoring methods and improve the continuity and completeness of monitoring data. Results and discussion: First, this study determined the initiation time of the landslide through the field investigation and collected five period of UAV data to analyze the overall displacement vector of the WLP landslide using sub-pixel offset tracking (SPOT). On the basis of the above data, we compensated for the missing data in GNSS system due to the practical monitoring vacancies by combining the field survey and the landslide-water level relationship. Based on these monitoring data, this paper points out that the WLP landslide is a buoyancy-driven landslide, and whether or not accelerated deformation will occur is related to the maximum reservoir water level. Finally, this study analyzed and discussed the applicability of UAV photogrammetry for reservoir landslide monitoring in the absence of ground control points (GCPs), and concluded that this method can be quickly and flexibly applied to the stage of large deformation of reservoir landslides. [ABSTRACT FROM AUTHOR]

In open-cast mines, a dump stability analysis is tedious for engineers. In the past, dump slope disasters have caused a loss of human resources and mining machinery. Sometimes, the machinery is stuck in a debris flow. Therefore, Susceptible Zone Identification (SZI) and its treatment are essential for the mining industry. This study aims to identify multiple failure zones in a large dump using a Multi Model Optimization (MMO) technique. Realistic 3D modelling is essential for accurate stability evaluation. Researchers have used 2D numerical modelling for dump slope stability analysis in many studies. However, the geometry of mine dumps is irregular because of unplanned Overburden (OB) material deposition. If the real 3D geometry of the dump is not considered, the slope stability results may confound researchers. Therefore, this study aimed to analyze the stability of the Sonepur Bazari mine dump with multiple failure zones using realistic 3D modelling. The Limit Equilibrium Method (LEM) and Finite Difference Method (FDM) were employed for slope stability analysis. This study investigated different critical zones in the entire dump. The advantage of this combined approach is that large internal and external dump failure zones can be quickly identified, and decisions can be made for mitigation. [ABSTRACT FROM AUTHOR]

Liquefied natural gas (LNG) storage tanks are an essential infrastructure for national energy security, and the monitoring of their integrity is the basis for ensuring the regular operation of storage tanks. Existing monitoring methods do not reflect changes in storage tanks well because most monitoring methods are based on a technical approach that allows only one type of monitoring data to be obtained, which does not give comprehensive monitoring results. In this study, we incorporate control measurements, light detection and ranging (LiDAR), unmanned aerial vehicle (UAV) photogrammetry, thermal infrared camera monitoring, interferometric synthetic aperture radar (InSAR), and other techniques. An integrated air--space--land multisource remote sensing monitoring scheme is proposed, and the scheme's feasibility is verified through actual measurements, providing strong support for subsequent, efficient, and all-around monitoring. [ABSTRACT FROM AUTHOR]

Old plantations are iconic sites, and estimating stand parameters is crucial for valuation and management. This study aimed to estimate stand parameters of a 115-year-old Japanese larch (Larix kaempferi (Lamb.) Carrière) plantation at the University of Tokyo Hokkaido Forest (UTHF) in central Hokkaido, northern Japan, using unmanned aerial vehicle (UAV) photogrammetry. High-resolution RGB imagery was collected using a DJI Matrice 300 real-time kinematic (RTK) at altitudes of 80 and 120 m. Structure from motion (SfM) technology was applied to generate 3D point clouds and orthomosaics. We used different filtering methods, search radii, and window sizes for individual tree detection (ITD), and tree height (TH) and crown area (CA) were estimated from a canopy height model (CHM). Additionally, a freely available shiny R package (SRP) and manually digitalized CA were used. A multiple linear regression (MLR) model was used to estimate the diameter at breast height (DBH), stem volume (V), and carbon stock (CST). Higher accuracy was obtained for ITD (F-score: 0.8–0.87) and TH (R2: 0.76–0.77; RMSE: 1.45–1.55 m) than for other stand parameters. Overall, the flying altitude of the UAV and selected filtering methods influenced the success of stand parameter estimation in old-aged plantations, with the UAV at 80 m generating more accurate results for ITD, CA, and DBH, while the UAV at 120 m produced higher accuracy for TH, V, and CST with Gaussian and mean filtering. [ABSTRACT FROM AUTHOR]

Urban storm drainage is essential for the large part of the population living in cities with torrential rains to protect public urban infrastructure, private property, and human lives from flooding. The most important design parameter for urban storm drainage is the flow discharge, which is normally calculated with the area, runoff coefficient, and rainfall intensity depending on basin delineation. This requires highly accurate topographic information on the urbanized terrain that digital elevation models sometimes do not meet due to the lack of resolution. This study proposes criteria for delineating urban basins considering urbanization without requiring the usual topographic surveys. The proposed basin delineation is based on a high-resolution digital elevation model obtained from an unmanned aerial vehicle (UAV) and field verification of flow directions. As a result, the delineation of two urban basins was obtained: an urban basin within an area that drains exclusively to a sinkhole and another basin that additionally drains out through other points of the divide. The latter basin does not comply with the tra)ditional concept of a hydrological basin because it has more than one outlet. In addition, this basin has an area that is 38% of the total area draining into the sinkhole. [ABSTRACT FROM AUTHOR]

Copyright of Türkiye Fotogrametri Dergisi is the property of Mersin University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Türkiye Fotogrametri Dergisi is the property of Mersin University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The NW-SE-trending dextral strike-slip faults on the north side of the Tian Shan, e.g., the Karatau fault, Talas–Fergana fault, Dzhalair–Naiman fault, Aktas fault, Dzhungarian fault, and Chingiz fault, play an important role in accommodating crustal shortening. The classic viewpoint is that these strike-slip faults are an adjustment product caused by the difference in the crustal shortening from west to east. Another viewpoint attributes the dextral strike-slip fault to large-scale sinistral shearing. The Alakol Lake fault is a typical dextral strike-slip fault in the north Tian Shan that has not been reported. It is situated along the northern margin of the Dzhungarian gate, stretching for roughly 150 km from Lake Ebinur to Lake Alakol. Our team utilized aerial photographs, satellite stereoimagery, and field observations to map the spatial distribution of the Alakol Lake fault. Our findings provided evidence supporting the assertion that the fault is a dextral strike-slip fault. In reference to its spatial distribution, the Lake Alakol is situated in a pull-apart basin that lies between two major dextral strike-slip fault faults: the Chingiz and Dzhungarian faults. The Alakol Lake fault serves as a connecting structure for these two faults, resulting in the formation of a mega NW-SE dextral strike-slip fault zone. According to our analysis of the dating samples taken from the alluvial fan, as well as our measurement of the displacement of the riser and gully, it appears that the Alakol Lake fault has a dextral strike-slip rate of 0.8–1.2 mm/a (closer to 1.2 mm/a). The strike-slip rate of the Alakol Lake fault is comparatively higher than that of the Chingiz fault in the northern region (~0.7 mm/a) but slower than that of the Dzhungarian fault in the southern region (3.2–5 mm/a). The Chingiz–Alakol–Dzhungarian fault zone shows a gradual decrease in deformation towards the interior of the Kazakhstan platform.

Ruins, marked by decay and abandonment, present challenges for digital documentation due to their varied conditions and remote locations. Surveying inaccessible ruins demands innovative approaches for safety and accuracy. Drones with high-resolution cameras enable the detailed aerial inspection and imaging of these inaccessible areas. This study investigated how surveying technologies, particularly Unmanned Aerial Vehicles (UAVs), are used to document inaccessible ruins. Integration with Real-Time Kinematic (RTK) technologies allows direct georeferencing in photogrammetric processing. A case study of the Castle of Terracorpo in Italy was used to demonstrate UAV-only surveying feasibility in inaccessible environments, testing two different scenarios. The first scenario involved the use of a DJI Matrice 300 RTK coupled with the D-RTK2 base station to survey the Castle; both direct and indirect georeferencing were exploited and compared through the photogrammetric process. This first scenario confirmed that this approach can lead to a centimetre-level accuracy (about three times the GSD value for indirect georeferencing and seven times the GSD value for direct georeferencing exploting RTK). The second scenario testing the integration of data from drones at varying resolutions enabled the comprehensive coverage of ruinous structures. In this case, the photogrammetric survey performed with the dji Mavic 3 Cine drone (indirect georeferencing) was integrated with the photogrammetric survey performed with the dji Matrice 300 RTK drone (direct georeferencing). This scenario showed that GCPs extracted from a direct georeferencing photogrammetric survey could be successfully used to georeference and integrate other drone data. However, challenges persist in surveying underground or enclosed spaces that are inaccessible to UAVs. Future research will explore integrating robotic LiDAR survey systems and advanced data fusion techniques to enhance documentation.

There are a large number of iron mine gobs due to many years of mining in Zhoutaizi Village, Zhangbaiwan Town, Luanping County. And some gobs have potential safety hazards of collapse, which seriously restrict the local economic development and social stability. So it is necessary to strengthen deformation investigation and field monitoring of existing gobs in this area. In this paper, the spatial distribution of gobs in the study area is determined and deformation of gobs is monitored by using Interferometric Synthetic Aperture Radar (InSAR), UAV photogrammetry and 3D laser scanning technology. Firstly, Small Baseline Subset InSAR (SBAS-InSAR) technology is used to retrieve the surface deformation of gobs. Then, a three-dimensional model of the study area is constructed by using UAV data, and the ground surface changes between two flights are calculated by using multi-period UAV flight data to support the results of InSAR technology. Finally, 3D laser scanning technology is applied to some areas, and the fine model of gobs is established. The results show that the joint monitoring results of the three technologies show a high consistency, the maximum deformation rate (−25 mm/a) of the study area are detected by InSAR method. Combined with the difference results of the DEM and 3D laser scanning data of the two periods of UAV, 17 high-risk areas of gobs are identified. The high-risk areas are distributed in various mining areas, and some areas have an impact on residential areas and roads. The based on Space, Sky and Ground multi-technology indicating that this method has high reliability and can be well applied to deformation investigation of goaf in mining area and the surface deformation monitoring during inadequate mining.

The 3D real scene model of high-steep rock slope established based on UAV image provides convenience for non-contact identification and interpretation of rock mass structures. The quality of 3D models directly influences the interpretability of rock mass structures. However, quantitative studies on the relationship between these two aspects are scarce. Therefore, this study investigates the influence of indicators such as photography distance (D), model brightness (l), angle between photography optical axis and the discontinuity to be interpreted (θd), and texture distortion area ratio (tdp), among others, on the interpretability of the 3D models. Furthermore, it delves into the relationships among these indicators and their practical application effects in complex high-steep rock slopes. On this foundation, a novel multi-indicator quality evaluation method for 3D models constructed using UAV photogrammetry is introduced for the first time. This method, based on a composite index model and incorporating empirical approaches, classifies the quality of 3D models into five levels. Guided by the quality evaluation results and taking into account the terrain development and geometric characteristics of discontinuities, a technical framework supporting the acquisition of high-quality 3D models is proposed, known as multi-angle nap-of-the-object image acquisition (MNIA). The research indicates that the 3D models established based on MNIA exhibit significantly reduced texture distortion, leading to a substantial improvement in recognizability, with a goodness rate of 79.98%, far surpassing that of oblique photogrammetry (41.18%). This study provides crucial guidance for obtaining high-quality UAV image in complex terrain environments and holds significant engineering application value in the fine identification and interpretation of rock mass structures on high-steep rock slopes.

ABSTRACTThis work presents the high-resolution high-accuracy orthophoto map and the Digital Surface Model of Forni Glacier (Italian Alps). These represent the status of the glacier tongue in mid-August 2022 when surveys were carried out with a DJI Phantom 4 RTK drone. The processing was carried out in Leica Infinity, and a 3 cm orthomosaic and a 20 cm Digital Surface Model were generated and made available for analysis of the current status of the glacier, which shows signs of downwasting, with the occurrence of collapsing areas and a rapidly changing proglacial landscape. This work can also be used as a reference to investigate the glacier evolution, also in light of climate change. Accuracy requirements of the deliverables were ensured by combining Post Processed Kinematic and Structure from Motion integrated with bundle block adjustment, and using Ground Control Points and Check Points, to guarantee redundancy and evaluate the geolocation accuracy and precision.

Pollarding oak trees is a traditional silvopastoral technique practiced across wide areas of the northern Zagros mountains, a unique and vast semi-arid forest area with a strong cultural and ecological significance. So far, the effects of pollarding on tree structure in terms of DBH (diameter at breast height)~H (height) relationships within the typical pollarding cycle, which often lasts 4 years, has not been scientifically described. Here, we combine field inventories of DBH with H obtained from photogrammetric UAV flights for the first time to assess DBH~H relationships within this system. We conducted the research at six pollarded forest sites throughout the Northern Zagros. The sampling encompassed all three main species of coppice oak trees. In the case of multi-stem trees, we used the maximum DBH of each tree that formed a unique crown. A linear relationship between UAV and extracted H and the maximum DBH of pollarded trees explained a notable part of the variation in maximum DBH (R2 = 0.56), and more complex and well-known nonlinear allometries were also evaluated, for which the accuracies were in the same range as the linear model. This relationship proved to be stable across oak species, and the pollarding stage had a notable effect on the DBH~H relationship. This finding is relevant for future attempts to inventory biomass using remote sensing approaches across larger areas in northern Zagros, as well as for general DBH estimations within stands dominated by pollarded, multi-stem coppice structures. [ABSTRACT FROM AUTHOR]

In recent years, unmanned aerial vehicles (UAVs) have become increasingly important as a tool for quickly collecting high-resolution (spatial and spectral) imagery of the Earth's surface. The final products are highly dependent on the choice of values for various parameters in flight planning, the type of sensors, and the processing of the data. In this paper ground control points (GCPs) were first measured using the Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) method, and then due to the low height accuracy of the GNSS RTK method all points were measured using a detailed leveling method. This study aims to provide a basic assessment of quality, including four main aspects: (1) the difference between an RGB sensor and a five-band multispectral sensor on accuracy and the amount of data, (2) the impact of the number of GCPs on the accuracy of the final products, (3) the impact of different altitudes and cross flight strips, and (4) the accuracy analysis of multi-altitude models. The results suggest that the type of sensor, flight configuration, and GCP setup strongly affect the quality and quantity of the final product data while creating a multialtitude model does not result in the expected quality of data. With its unique combination of sensors and parameters, the results and recommendations presented in this paper can assist professionals and researchers in their future work. [ABSTRACT FROM AUTHOR]

The reliable in situ quantification of rock mass fracturing and engineering quality is critical for slope stability, surface mining and rock engineering applications, yet it remains difficult due to the heterogeneous nature of fracture networks. We propose a method to quantify and map the slope-scale geomechanical quality of fractured rock masses using infrared thermography (IRT). We use the Mt. Gorsa quarry (Trentino, Italy) as a field laboratory to upscale a physics-based approach, which was developed in the laboratory, to in situ conditions, including the effects of fracture heterogeneity, environmental conditions and IRT limitations. We reconstructed the slope in 3D using UAV photogrammetry, characterized the rock mass quality in the field at selected outcrops in terms of the Geological Strength Index (GSI) and measured their cooling behavior through 18h time-lapse IRT surveys. With ad hoc field experiments, we developed a novel procedure to correct IRT data in outdoor environments with complex topography. This allowed for a spatially distributed quantification of the rock mass surface cooling behavior in terms of a Curve Shape Parameter (CSP). Using non-linear regression, we established a quantitative CSP-GSI relationship, which allowed for the CSP to be translated into GSI maps. Our results demonstrate the possibility of applying infrared thermography to the slope-scale mapping of rock mass fracturing based on a physics-based experimental methodology. [ABSTRACT FROM AUTHOR]

Rockfall event is common on rocky terrain, and it threatens people. Recent advances in remote sensing technologies allow us to model the terrain with high accuracy and resolution. In this study, we show the application of modeling a rockfall site in three-dimensional (3D) using an unmanned aerial vehicle. The acquisition of information about discontinuities in the rock masses using 3D point clouds is vital to characterize rockfall dynamics. We obtained 3D spatial information and point clouds of a rocky slope from acquired images. We extracted 10 discontinuity sets from the 3D model as they have significant effects on the failure mechanism. Details in mapping discontinuities have improved significantly with the help of point clouds. The results are beneficial for modeling the terrain of inaccessible areas with high resolution and obtaining information from those areas. This paper shows how can point cloud analysis be applied to characterize discontinuity sets. [ABSTRACT FROM AUTHOR]

Copyright of Remote Sensing for Natural Resources is the property of Remote Sensing for Natural Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of unmanned aerial vehicles (UAVs) for photogrammetry allows the rapid acquisition of high-resolution images of geological masses in complex landforms. However, effective analysis of the acquired image information remains a key research issue. At K158 + 837 on the Chongqing-Huaihua Railway, Baima jointed rock masses were reconstructed with high accuracy using UAV close-range photogrammetry technology, and rock discontinuities were extracted from the projected image. The proposed modeling algorithm for jointed rock masses enables the preprocessing of two-dimensional jointed rock mass slopes. Numerical simulations using the disk-based discontinuous deformation analysis method show that the discontinuity network formed by initial cutting significantly affects the subsequent crack development. Meanwhile, simulation results under different scenarios indicate the importance of the pre-reinforcement measures applied to unstable rock masses. The workflow developed based on these results can serve as a reference for the comprehensive acquisition, recognition and numerical modeling analysis of similar jointed rock masses.

Abstract The construction of the St. Adalbert Church in Gdansk dates to 1310. It is a church of rich history and great historical value, and its care is challenging. In this study, the combination of unmanned aerial vehicle (UAV) photogrammetry and terrestrial laser scanning (TLS) was used to accurately build a 3D model of the church. Together with the collected historical inventory documentation, the historic building information model (HBIM) was generated. The Autodesk-Revit® tool was used for this purpose. On the basis of the generated model, the reflection properties of the laser scanner beam and red–green–blue (RGB) images, a methodology was proposed for analysing the degradation of the church’s components. The main hypothesis of this study is based on the analysis of sunlight outside the church. In addition to the importance of the method for determining the risks of church degradation, a high-quality method for model visualization combining two photogrammetric techniques (TLS + UAV) is presented.