UAV Survey Research Articles

Application of integrated geodetic and UAV technologies for monitoring environmental changes due to the mining activities in Solotvyno salt mine, Ukraine

This paper covers the spatio-temporal evolution of land surface deformation in the Tisza River basin within the Transcarpathian region, analyzing geodetic observations obtained over the last decade. In the town of Solotvyno, in the western part of Ukraine, near the Romanian border, there is an abandoned salt deposit where salt was extracted in several mining operations. In 2010, the mine was closed, and mine chambers 7 and 8 were flooded with water, causing the collapse of this region. Since then, the extent of the damage has been increasing, with sinkholes steadily growing larger and larger, threatening not only the entire surface area around the quarry but especially the groundwater that connects the deposit to the Tisza River. Several research institutions have been involved in monitoring the shifts over time. We have monitored the karst by identifying the most dangerous areas of the earth's surface subject to vertical shifts - trench sinkholes by UAV survey and terrestrial measurements using precise levelling in 4 stages. The situation on the site is an emergency with a major ecological impact of salt contamination in the whole Upper Tisza Basin region and requires not only continuous geodetic, geological, and chemical monitoring but especially an urgent solution to reverse the state of damage to the region.

Characterizing the evolution of the Daguangbao landslide nearly 15 years after the 2008 Wenchuan earthquake by InSAR observations

The Daguangbao landslide (DGBL), the largest landslide triggered by the 2008 Ms 8.0 Wenchuan earthquake, has received much attention, but its long-term post-earthquake evolution and driving force of activity are still poorly understood. As the evolutionary behavior of the DGBL is complicated by the influence of mainshock, aftershocks and rainfall, it is of great significance to study the dynamics of the landslide. In this study, a systematic and comprehensive framework for assessing the long-term stability and risk of co-seismic landslides was proposed. Based on ALOS-1 and Sentinel-1 data, time-series InSAR technology was used to reveal the nearly 15-year post-seismic evolution characteristics of the DGBL at different stages, followed by the prediction of the stabilization time, the estimation of the landslide thickness and risk assessment. The first stage was identified as three years after the earthquake (2008–2011). During this stage, ALOS-1 results show that the deformation of DGBL was intense (300 mm/year) with uneven spatial distribution, and an aftershock (Ms 5.3), along with increased rainfall, triggered its acceleration in 2009. The second stage was the period from 2014 to 2022. For this stage, we used the mass conservation approach to invert the thickness of the DGBL, revealing that a new sliding surface and thickness center had formed following the co-seismic failure in 2008. Sentinel-1 time series results indicated that the DGBL remains active even 15 years after the Wenchuan earthquake, but the deformation of DGBL has significantly slowed down (50 mm/year). The stabilization time for different segments of DGBL was predicted to range from 2027 to 2040 according to an exponential model. Beyond the overall trend of recovery, seasonal movements (including localized acceleration in 2021) closely related to rainfall remained evident, but the impact of aftershocks on the DGBL was severely weakened over time. UAV and field survey results suggested that the risk of localized debris flows at DGBL still exists. Our study improves our understanding of the long-term evolutionary pattern of DGBL and provides an important reference for post-earthquake landslide risk assessment and disaster prevention.

A low-cost UAV survey can unravel Baird's Tapir (Tapirus bairdii) trail network dynamics in a neotropical highland forest

UAV technology has transformed spatial data collection and high-spatial resolution analysis of diverse environments around the world. Its role within geosciences, ecology, engineering, and other sciences has been increasing withing the last decade. In ecological and geomorphological aspects, it offers a powerful tool for studying landforms, surface processes, vegetation, and animal behavior globally. Our study employs high-resolution UAV surveys to analyze Tapirus bairdii trail networks and their connection to the landscape in a Costa Rican highland paramo-forest national park. Using a DJI Phantom 4 V.2 UAV, we conducted a photogrammetric flight over 3.19 ha, producing datasets with a spatial resolution of 2.99 cm/pixel. These datasets facilitated geostatistical analysis of Tapirus bairdii trails, revealing their complexity and hotspots near lagoons. We investigated lagoon characteristics, finding that finer sediments spatially correspond with higher trail activity. This suggests that sediment types in lagoons influence Tapirus bairdii navigation, impacting trail network composition. Our findings highlight UAV technology's role in advancing ecological and geomorphological research in protected areas, providing insights into Tapirus bairdii behavior within highland ecosystems. Overall, to the date this is the first high-resolution UAV survey of Tapirus bairdii within these types of highland tropical environments.

Enhanced structural analysis through a hybrid analogue-digital mapping approach: Integrating field and UAV survey with microtomography to characterize metamorphic rocks

This study focused on collecting structural data orientations of a crustal-scale shear zone (Palmi Shear Zone, PSZ, southern Calabria, Italy) by integrating various analytical and field-based techniques. The PSZ consists of deformed metamorphic rocks (migmatitic biotitic paragneiss, marbles, and skarns) showing multiple folding phases, and Hercynian tonalites and pegmatites (306-290 Ma), crosscut by Late Hercynian leucocratic dykes (ca. 290 Ma). Multi-sized clasts composed of different lithologies are preserved on clean outcrop surfaces, and are sheared into both σ - and δ -type objects that collectively suggest opposing senses of shear. The study incorporates structural analysis of folds, field and aerial surveys (UAV), digital mapping, and microcomputed tomography. Various kinematic indicators were observed in the PSZ, indicating a mix of factors influencing the shear strain patterns (e.g. fold interference patterns, different rock types with high viscosity contrast). The findings suggest a clear consistency between structural data inferred from 3D VOM (Virtual Outcrop Model) and those collected directly in the field, confirming the occurrence of both sinistral and dextral shear in the PSZ, providing important insights into the tectonic evolution of the Calabrian-Peloritani Terrane.

UAV survey mapping of illegal deforestation in Madagascar

Societal Impact StatementUnmanned aerial vehicle (UAV) imagery highlights the extent of illegal deforestation in protected areas for the biodiverse humid forest of central Madagascar. The ultra‐high‐resolution (<10‐cm pixel) images enable the creation of detailed forest 3D base maps and provide the means to quantify forest stand losses. To help communities safeguard their forests, local non‐governmental organisations can use UAV maps in combination with weekly deforestation alerts to facilitate an immediate on‐ground response that significantly restricts illegal activity. Integrating ultra‐high‐resolution UAV mapping and coarse‐resolution freely available satellite imagery should have much wider applications in Madagascar and the humid tropics for community‐based conservation.Summary This study of the Ambohimahamasina humid forest shows that small UAVs offer a detailed (<10‐cm pixel), rapid and cost‐effective solution to provide maps of detailed deforestation patterns not visible in satellite imagery. Calculating forest extent and volume are valuable ways to rapidly assess forest losses and prioritise areas for ground patrols. The use of 3‐dimensional measurements for above ground carbon estimates indicate how, in the future, these metrics could be used to calculate carbon payments for conservation programs. By combining UAV and free satellite imagery, an effective alert system has been developed that supports community initiatives in the protection of their natural forest resources. The wealth of ultra‐high‐resolution UAV data collected in this study provides insights into forest dynamics, supports local community forest management, and has the potential to measure the value of the forest.

Inferring channel incision in gravel‐bed rivers: Integrating LiDAR data, historical aerial photographs and drone‐based SfM topo‐bathymetry

AbstractChannel incision is an evident trend for river evolution in many European rivers and notably the Western Carpathians, whose former braided and multichannel wandering river system is transforming into a single‐thread channel, but it is often difficult to separate drivers and determine if incision is finished or is still ongoing. To overpass these research gaps, this paper presents an innovative approach to assess the multidecadal incision of the Belá River in the Western Carpathians since 1949 by LiDAR‐based analyses of floodplain surfaces above the river channel dated from historical aerial images. Detailed analyses of ongoing incision were also calculated based on DEM of differences (DoD) using Structure‐from‐Motion (SfM) photogrammetry‐derived topo‐bathymetric models. The study applied the BACI (Before‐After‐Control‐Impact) approach that compared pre‐state (Before), post‐state (After) and reach (Control) that is not affected by potential external effects with degraded (impacted) reach to be able to distinguish the driver effects. Floodplain channel surface analyses indicate the maximum incision up to 4 m and incision rate of 5.7 cm/year that occurred in the most degraded reach. Moreover, cross‐section profiles point to accelerated incision of 24.5 cm/year in the last 10 years (2011–2021) by the propagation of incision upstream. Overall, the net changes from the UAV survey pointed to 22 759 m3 of gravel sediments, constituting outwash from the 1.6 km long channel system (2015–2022) by incision, whereas analyses of historical channel surfaces estimated erosion of 573 303 m3 from impacted reaches between 1949 and 2020. Incision evidence is only observed in the downstream part below the control section due to local drivers (channel regulation, comprising embankment and gravel mining that activated a backward erosion of the system with knickpoint migration upstream). This analysis shows the benefits of combining different sources of data to separate long‐term and ongoing channel responses and the BACI‐approach to better target cause–effect relationships in space and time.

Створення тривимірної моделі культової споруди за даними комбінованих геодезичних знімань

The purpose of the research is to test algorithms for creating a three-dimensional model of an object based on point clouds obtained from combined geodetic surveys (UAV survey and ground laser scanning). The methodology is based on the collection of a cloud of points by ground laser scanning and the acquisition of a cloud of points on the same object by the photogrammetric method based on data taken from a UAV. The formation of the resulting three-dimensional model is performed according to the most reliable data from the point of view of geometric accuracy. The results. Each of the point cloud acquisition methods (UAV or laser scanning) has its advantages for certain parts of the building. Thus, the modeling of the upper part of the building, sloping and complex roofs is best performed based on the data taken from the UAV, vertical walls and the elements placed in them (windows, decoration elements, etc.) – based on point clouds obtained from laser scanning. Scientific novelty and practical significance. The method of processing point clouds obtained from various sources on the basis of free software was tested. The approach discussed in the article has significant potential for use in many branches of the national economy. The performer can combine measurement data from various sources on the basis of free software and prepare them for further export to the necessary software for creating a model.

Contrasting Changes of Debris-Free Glacier and Debris-Covered Glacier in Southeastern Tibetan Plateau

Debris-free and debris-covered glaciers are both extensively present in the southeastern Tibetan Plateau. High-precision and rigorous comparative observational studies on different types of glaciers help us to accurately understand the overall state of water resource variability and the underlying mechanisms. In this study, we used multi-temporal simultaneous UAV surveys to systematically explore the surface elevation change, surface velocity, and surface mass balance of two representative glaciers. Our findings indicate that the thinning rate in the debris-free Parlung No. 4 glacier UAV survey area was consistently higher than that in the debris-covered 24K glacier in 2020–2021 (−1.16 ± 0.03 cm/d vs. −0.36 ± 0.02 cm/d) and 2021–2022 (−0.69 ± 0.03 cm/d vs. −0.26 ± 0.03 cm/d). Moreover, the surface velocity of the Parlung No. 4 glacier was also consistently higher than that of the 24K glacier across the survey period, suggesting a more dynamic glacial state. The surface mass balance of the Parlung No. 4 glacier (2020–2021: −1.82 ± 0.09 cm/d; 2021–2022: −1.30 ± 0.09 cm/d) likewise outpaced that of the 24K glacier (2020–2021: −0.81 ± 0.07 cm/d; 2021–2022: −0.70 ± 0.07 cm/d) throughout the observation period, which indicates that the debris cover slowed the glacier’s melting. Additionally, we extracted the melt contribution of the ice cliff area in the 24K glacier and found that the melt ratio of this ‘hotspot’ area ranged from 10.4% to 11.6% from 2020 to 2022. This comparative analysis of two representative glaciers provides evidence to support the critical role of debris cover in controlling surface elevation changes, glacier dynamics, and surface mass balance.

Пространственное моделирование органического вещества почвы опытных делянок на основе данных с БПЛА

The article presents the results of spatial geostatistical and regression modeling of soil organic matter in a section of an experimental field on the territory of the Educational, Scientific and Experimental Field of the Perm State AgroTechnical University. The purpose of the research is to model the spatial distribution of soil organic matter in the experimental plot using UAV survey data. The research area covers an area consisting of 20 plots of one of the experimental fields with an area of 0.34 hectares, on which a UAV survey was carried out on September 12, 2023 and the content of organic matter was analyzed. Spatial modeling was carried out using geostatistical and regression methods based on 20 points representing the centroids of experimental plots. As a result of the research, an average relationship between the content of organic matter and elevation and distance to watercourses was established. With regression modeling, the range of values of the distribution of organic matter is narrowed by approximately 0.5% from the minimum and maximum compared to the geostatistical model. Keywords: UAV, GEOINFORMATIONAL MAPPING, SOIL ORGANIC MATTER

EXPLORING VERY HIGH-RESOLUTION REMOTE SENSING FOR ASSESSING LAND SURFACE TEMPERATURE OF DIFFERENT URBAN LAND COVER PATTERNS

Abstract. Very-high-resolution thermal infrared data has a good potential to detect and monitor LST variations in urban areas. In this work, an attempt was made to estimate Land Surface Temperature (LST) from very high resolution (VHR) data using machine learning technics in an area of Botanical garden of Yerevan, Armenia; UAV-derived and in-situ measured high precision LST of various land cover (LC) patterns were then compared for September and October. The main purpose of this study was to explore the capabilities of UAV imagery (multispectral/TIR) in assessing LST of the different LC patterns. For this purpose, a UAV survey was performed, and VHR data were collected using multispectral and TIR thermal camera while in-situ measurements of temperature and surveying of the different LC patterns were performed. A significant correlation was detected between LSTs in situ measured and detected by UAV in 06 September (r=0.758; p-value <0.01) and in 27 October (r=0.686; p-value <0.01). When comparing the LSTs of separate land-cover patterns the best results were received for Bare soils (r=0.591; p-value <0.05) and Concrete (r=0.927; p-value <0.01) when the survey and measurements was done in September. Despite its limitations, it can be stated that UAV thermal survey has a good potential to detect and monitor LST variations in urban areas.

Building 3D CityGML models of mining industrial structures using integrated UAV and TLS point clouds

Mining industrial areas with anthropogenic engineering structures are one of the most distinctive features of the real world. 3D models of the real world have been increasingly popular with numerous applications, such as digital twins and smart factory management. In this study, 3D models of mining engineering structures were built based on the CityGML standard. For collecting spatial data, the two most popular geospatial technologies, namely UAV-SfM and TLS were employed. The accuracy of the UAV survey was at the centimeter level, and it satisfied the absolute positional accuracy requirement of creating all levels of detail (LoD) according to the CityGML standard. Therefore, the UAV-SfM point cloud dataset was used to build LoD 2 models. In addition, the comparison between the UAV-SfM and TLS sub-clouds of facades and roofs indicates that the UAV-SfM and TLS point clouds of these objects are highly consistent, therefore, point clouds with a higher level of detail and accuracy provided by the integration of UAV-SfM and TLS were used to build LoD 3 models. The resulting 3D CityGML models include 39 buildings at LoD 2, and two mine shafts with hoistrooms, headframes, and sheave wheels at LoD 3.

Influence of quantity, quality, horizontal and vertical distribution of ground control points on the positional accuracy of UAV survey

Influence of quantity, quality, horizontal and vertical distribution of ground control points on the positional accuracy of UAV survey

Web Mapping for Farm Management Information Systems: A Review and Australian Orchard Case Study

A web mapping XYZ Tile Layer Service, such as Google Earth (GE), provides an amazing resource for the visualization of spatial data against aerial and satellite imagery with global coverage, typically at a resolution finer than 5 m. However, the increasing requirement on spatial accuracy in farm information requires a greater appreciation of the issues involved in the use of such services. Position errors can be created in the georeferencing and orthorectification of images, transformation between reference frames (datums) in map projection, e.g., using a spheroid as compared to an ellipsoid earth model, and tectonic shifts. A review is provided of these issues, and a case study is provided of the horizontal positional accuracy of web map imagery for Australian mango orchards. Positional accuracies varied from 1.804 to 6.131 m across four farms using GE 2021 imagery, between 1.556 and 3.365 m in one farm for the most recent imagery available from each of four web map providers, and from 0.806 m (in 2016) to 10.634 m (in 2003) in one farm for the period of 2003 and 2021 using the historical GE imagery resource. A procedure involving the estimation of four transformation parameters was demonstrated for the alignment of GNSS data with GE imagery. However, as the scale factor was unity and the rotational value was near zero, the use of a simple horizontal mean shift vector was recommended. Further recommendations are provided on (i) the use of web mapping services, with a comparison of the use of UAV survey imagery, and (ii) the need for metadata, particularly the date of collection, on collected position data, in the context of use in farm management information systems.

UAV and field survey observations on the November 26th 2022 Celario flowslide, Ischia Island (Southern Italy)

ABSTRACT On 26th November 2022, a heavy cloudburst affected Ischia Island (Southern Italy) causing a flash flood and triggering several flowslides. The most affected municipality was Casamicciola Terme, where this event produced 12 casualties, more than 200 people evacuated and several damages to the buildings and the road network. The largest flowslide involved Celario watershed, which started as a small slide (around 10 m3) on the top of Mt. Epomeo at 703 m a.s.l. of height and impacted downward at 645 m a.s.l., successively channelising in the catchment. This study summarises the geological and geomorphological evidence collected during the field investigation of the Celario flowslide and analyses the remotely sensed UAV data to reconstruct the occurred scenario. Finally, some considerations on the relationships between the occurred damage and the flowslide impact are discussed.

Research on Blended Teaching Design of UAV Survey Course

In this paper, a hybrid teaching model for this course has been designed by analyzing the current situation of drone survey course construction, combined with the classification and characteristics analysis of online teaching resources. The application of blended learning can enhance students' initiative in learning, stimulate innovation awareness, and improve the quality of course teaching.

Some new knowledge brought by 3D digitizations of the chapel of Kerfons (Brittany)

A few kilometers upstream from Lannion in Brittany, we can find the chapel of Kerfons. It was built on the lands of the ancient fief of Coatfrec, and the ruins of the castle are located further north on the western bank of the Léguer river. The chapel’s architecture is a mix of two styles: the flamboyant Gothic in the nave and northern chapel, and the first Breton Renaissance in the southern arm. Recognized as a Historic Monument since 1910, it boasts a remarkable flamboyant Gothic rood screen made of polychrome wood. Recently, a company conducted a voluntary 3D scanning campaign using two laser scanners to capture the chapel’s exterior and interior. From this data, we extracted unpublished plans and orthophotographs, and conducted initial investigations to answer archaeological questions about the positioning of the rood screen and the edges of the Kerfon chapel’s roof, which were previously unexplained. To address other questions about the higher exterior parts, we also conducted an UAV survey around the sculpted statues of the bell tower, the elements above the Renaissance stained glass window, and the stone under Christ’s feet of the calvary. Despite the lack of dedicated funding, these new archaeological findings contribute to the preservation and enhancement of the chapel, as well as encouraging the application of this approach to other buildings that may not have a dedicated budget for their digitization.

RATES OF MODERN DENUDATION OF A SMALL CATCHMENT IN THE MIDDLE MOUNTAIN BELT OF THE GREATER CAUCASUS (CASE STUDY OF THE GITCHE-GIZHGIT CATCHMENT)

The volumes of loose-clastic material moved by modern earth surface processes were quantified for a small mid-mountain catchment area ( F = 1,86 km2), located in the Baksan River basin using a number of independent methods (modeling of erosion and geomorphologic mapping). The total volume of removed material was estimated through the assessment of the thickness of bottom sediments accumulated in a reservoir located in the outlet section of the catchment area. The rates of linear and rill erosion have been found using the results of repeated UAV surveys and the pin method. The rates of rockfall processes are estimated on the basis of repeated ground-based laser scanning. Additionally, published data on the rates of earth surface processes in the mountains were used. Based on the results of field mapping and interpretation of space images, a map of the spatial pattern of leading earth surface processes was compiled. A digital terrain model of the catchment was constructed on the basis of detailed UAV survey. The volume of loose clastic material delivered to the reservoir was estimated using data on the average annual rates of leading earth surface processes, a map of their distribution over the catchment area, and the connectivity index. It has been established that the average annual denudation rate within the catchment area is 0,16 mm/year. At the same time, only about 3-10% of the products of denudation are delivered to the reservoir. The sediment yield, calculated on the basis of the volume of sediments in the reservoir, is 514 t/km2 per year. It is comparable to the sediment yield of small rivers draining the mid-mountain belt of the Alps with similar bedrock lithology, which was calculated using the results of long-term observations of water and sediment discharge at gauging stations.

MULTI-SENSOR ANALYSIS FOR EXPERIMENTAL DIAGNOSTIC AND MONITORING TECHNIQUES AT SAN BEVIGNATE TEMPLAR CHURCH IN PERUGIA

Abstract. In the contemporary world, human and natural calamities are challenging our capabilities to preserve heritage and develop innovative safeguard strategies that also address the requirement of sustainability for restoration purposes, still considering the connection between tradition and innovation. This work introduces non-invasive diagnostic practices that offer a new insight of the built environment by studying two different elements of the same architecture of San Bevignate Templar church: a thermographic mapping obtained with special post-processing procedures provided interesting information about the hidden wall pattern, while a prototypal laser scanner, called RGB-ITR, and a UAV survey supplied new insights on the precious paintings. The assessment of the masonry quality constitutes an a priori condition for a reliable estimation of its seismic vulnerability and for the planning of effective yet conservative interventions. The access keys to 'sustainability' therefore consist in the improvement of these contactless investigations, which can be performed both in passive conditions, in the case of thermography surveys, and in active ones, such as for the RGB-ITR scanner, as necessary substitutes for destructive or partial-destructive tests. The research achieved promising results for the characterisation of the architectural structure and the paintings, with the aim of a long-term monitoring of the structure and the decorative apparatus of a monumental heritage located in an area vulnerable to seismic and environmental events.

How Many Reindeer? UAV Surveys as an Alternative to Helicopter or Ground Surveys for Estimating Population Abundance in Open Landscapes

Conservation of wildlife depends on precise and unbiased knowledge on the abundance and distribution of species. It is challenging to choose appropriate methods to obtain a sufficiently high detectability and spatial coverage matching the species characteristics and spatiotemporal use of the landscape. In remote regions, such as in the Arctic, monitoring efforts are often resource-intensive and there is a need for cheap and precise alternative methods. Here, we compare an uncrewed aerial vehicle (UAV; quadcopter) pilot survey of the non-gregarious Svalbard reindeer to traditional population abundance surveys from ground and helicopter to investigate whether UAVs can be an efficient alternative technology. We found that the UAV survey underestimated reindeer abundance compared to the traditional abundance surveys when used at management relevant spatial scales. Observer variation in reindeer detection on UAV imagery was influenced by the RGB greenness index and mean blue channel. In future studies, we suggest testing long-range fixed-wing UAVs to increase the sample size of reindeer and area coverage and incorporate detection probability in animal density models from UAV imagery. In addition, we encourage focus on more efficient post-processing techniques, including automatic animal object identification with machine learning and analytical methods that account for uncertainties.

Soil loss through fissures and its responses to rainfall based on drip water monitoring in karst caves

Owing to the binary geologic structure, soil loss in the karst region is characterized as a combination of surface erosion and underground soil loss. However, we know little about the process and amount of underground soil loss by now due to the difficulty in observation and identification. To predict soil loss accurately and control rocky desertification effectively, it is urgent to collect data of underground soil loss directly by new ways. In this study, 137Cs tracer technique, high frequency online monitoring and UAV survey were used to investigate soil loss through fissures. The soil samples were collected in five karst caves of Guizhou Province for determining 137Cs activity. In two of these caves, the improved monitoring devices were adopted to monitor drip water online, and the sediment content in drip water was measured once a month. Furthermore, depending on 5 exposed karst sections, the distribution density of fissures was surveyed with UAV to calculate the average underground soil loss modulus in the watershed. The results showed that (1) the soil materials deposited in caves were mainly transported by runoff from the cave entrance, rather than through fissures above the caves. (2) The initial response time and duration of drip water in caves to rainfall were controlled by surface land coverage and the process of precipitation. And the variation of sediment content in drip water kept almost constant with rainfall except at the beginning of the rainy season. (3) The directly measured underground soil loss rate monitored through the fissure above a cave with high bedrock exposure rate and a cave with high vegetation coverage was 2.42 g·yr−1 and 0.36 g·yr−1, respectively. (4) The average underground soil loss modulus in the area with high bedrock exposure rate and with high vegetation coverage was 0.35 t·km−2·yr−1 and 0.05 t·km−2·yr−1, respectively. This study is helpful for understanding the process and intensity of underground soil loss.