Aerial Photogrammetric Survey Research Articles

Engineering and environmental assessment of soilbag-based slope stabilisation for sustainable landslide mitigation in mountainous area

Changes in land use significantly impact landslide occurrence, particularly in mountainous areas in northern Thailand, where human activities such as urbanization, deforestation, and slope modifications alter natural slope angles, increasing susceptibility to landslides. To address this issue, an appropriate method using soilbags has been widely used for slope stabilisation in northern Thailand, but their effectiveness and sustainability require assessment. This research highlights the need to evaluate the stability of the soilbag-based method. In this study, a case study was conducted in northern Thailand, focusing on an area characterised by high-risk landslide potential. This research focuses on numerical evaluation the slope stability of soilbag-reinforced structures and discusses environmental sustainability. The study includes site investigations using an unmanned aerial photogrammetric survey for slope geometry evaluation and employing the microtremor survey technique for subsurface investigation. Soil and soilbag material parameters are obtained from existing literatures. Modelling incorporates hydrological data, slope geometry, subsurface conditions, and material parameters. Afterwards, the pore-water pressure results and safety factors are analysed. Finally, the sustainability of soilbags is discussed based on the Sustainable Development Goals (SDGs). The results demonstrate that soilbags effectively mitigate pore-water pressures, improve stability, and align with several SDGs objectives. This study enhances understanding of soilbags in slope stabilisation and introduces a sustainable landslide mitigation approach for landslide-prone regions.

Недеструктивно археологическо проучване в местността „Долната чатма“ при село Велино, Шуменско

In the late autumn of 2022, a non-destructive archaeological survey was carried out in the territory of Velino village, Shumen municipality. The survey went through several stages: 1) collection of preliminary information on the names of localities and toponyms in the area of the survey; 2) conducting a field survey during which accumulations of large unprocessed stones and a relatively large concentration of fragmented Old Bulgarian household ceramics were registered; 3) aerial photogrammetric survey of the terrain, as a result of which a digital elevation model and an ortho-photo plan of the area designated for study were produced. The contours of linear structures of artificial origin were clearly visible; 4) geophysical survey in four zones, which confirmed the proposals for the presence of anomalous zones; 5) vertical electric sounding with the aim of studying the stratigraphy of the object during which it was established that the structures probably develop at a depth of 0.80-1.00 m from the contemporary terrain. The results of the non-destructive archaeological survey in Dolnata Chatma locality, near the village of Velino, Shumen region show that linear stone structures develop on the flat terrace east of the village, probably part of a presumed archaeological object. At this stage, its scope, chronology and character are not clarified, and this remains a task for the team in future exploratory and subsequently regular archaeological surveys.

Geological-technical study for the design of an underground variant of S.S. 52 “Carnica” in the Passo Mauria area (Carnic Alps)

This study aims to define a preliminary geological model of the Passo Mauria tunnel, designed as an alternative underground route to the current S.S.52 to ensure a safer connection over the top way Belluno (A27 Highway) Tolmezzo (A23 Highway), on which various tourist and economic activities revolve. The survey stage has allowed us to describe and represent the cartographic elements that describe the geology of the study area. The study has mainly focused on the investigation of the presumed entrances of the tunnel, characterized by specific geological and geomorphological conditions. The aerial photogrammetric survey supported the reconstruction of the geometry of discontinuities in the non- accessible areas. Besides, this study has allowed the definition of the possible behaviour of the rock mass subjected to the tunnel excavation and of sections with homogeneous mechanical properties. The drafting of a survey plan supplements the study to determine a geological and geotechnical model, for the subsequent investigation and design phases.

Unveiling Fernando de Noronha Island's photovoltaic potential with unmanned aerial survey and irradiation modeling

The universalization of electricity still presents significant obstacles to achieving the United Nations Sustainable Development Goals. There are still many remote areas, such as oceanic islands and isolated communities disconnected from the grid, that depend on fossil fuels to make it viable. Fernando de Noronha, a tropical oceanic island in Brazil, is a typical case where replacing the diesel-based power plant for renewable energy is imperative, therefore, it served as a testbed for this investigation. This paper presents the implementation and results of a low-cost framework for assessing the photovoltaic potential of rooftops. Using a real case study, the objective is to explore how effective rooftop photovoltaic systems could be on Fernando de Noronha Island by applying low-cost aerophotogrammetry, geospatial analysis and scenario creation. The first approach was mapping buildings, open spaces and solar obstacles using unmanned aerial photogrammetric survey that delivered high-quality digital elevation surface. The 3D rooftop surfaces fed the solar irradiation models and enabled to compute the photovoltaic potential of suitable rooftops. Findings show that 83.3% of the total building rooftop area was deemed economically viable for photovoltaic installations. Furthermore, 80.0% and 60.0% of the rooftops receive annual irradiation levels >1600 kWh/m2 and 2000 kWh/m2, respectively, indicating high potential for exploiting solar resources on decentralized, highly irradiated rooftops. The scenario with the highest photovoltaic potential is three times higher than the lowest. The results indicate that the suitability of rooftops for various photovoltaic system sizes offers the possibility of deploying a combination of smaller and larger urban photovoltaic installations. Furthermore, the decentralized photovoltaic rooftops can compensate for between 66 and 199% of the estimated annual consumption of 31 GWh in 2031. The method is highly transferrable and limited solely by the availability of sources of geospatial data and coordination with stakeholders. The investigation meets the needs of the Brazilian Ministry of Mines and Energy, therefore meeting the environmental needs of the energy sector by promoting renewable energy for the island which is a UNESCO Natural World Heritage Site and Brazilian National Marine Park and Environmental Protected Area. The investigation demonstrated that creating photovoltaic potential scenarios that nurture informed decision-making processes is a crucial initial step in urban renewable energy planning. The pioneering 2000-ha unmanned aerial photogrammetric survey proved to be a cost-efficient method for producing accurate data for modeling the irradiation and photovoltaic potential in urban areas. The investigation fills the literature gap on modeling photovoltaic potential for remote islands by blending unmanned aerial vehicles and geospatial tools.

Geographic variation in external morphology of North Pacific and Southern Hemisphere blue whales (Balaenoptera musculus)

Geographic variations in size and proportions of blue whales (Balaenoptera musculus) were investigated using length data acquired from whaling records and aerial photogrammetric surveys. Results showed that blue whales found in the eastern Pacific off Central and North America are significantly shorter (by approximately 2m) than blue whales found at higher latitudes in the North Pacific. Results support the occurrence of a morphologically distinct eastern North Pacific (ENP) blue whale population which migrates in spring/summer from warm waters off Central America and Mexico to temperate feeding grounds along the west coast of North America. Southern Hemisphere blue whales sampled with vertical aerial photogrammetry off northern Peru and the Galapagos Islands were similar in size to the ENP blue whales. However, the population affinity of these southern blue whales remains uncertain. No length data were available for blue whales formerly captured off southern Japan and Korea. Nonetheless, a history of diminishing fishery catches and a lack of any recent sightings suggests that these whales were members of a geographic population that is now severely depleted or extinct. Based on comparisons of total length, length of rostrum and length of tail region, ENP blue whales were found to be morphologically similar to the ‘pygmy’ blue whale (B.m. brevicauda) described from the Kerguelen Island region of the southern Indian Ocean. ‘Antarctic’ blue whales (B.m. intermedia) from the Southern Ocean were found to be statistically significantly larger than their conspecifics at high latitudes in the North Pacific. These results support the hypotheses that blue whales that migrate from warm seas to cold feeding grounds in high latitudes are larger than those whose distributions are limited to low and mid-latitudes. Differences in morphology may reflect selective pressure on populations to adapt physiologically to energy demands associated with different migration, environmental and ecological regimes. As some of the results come from populations located far apart in different oceans, questions remain concerning the continuity of populations within and among ocean basins. Consequently, research using fishery data and approaches such as photogrammetry, telemetry, acoustics and molecular genetic analysis should be continued to better understand the worldwide blue whale population structure.

Rapid seismic risk assessment of bridges using UAV aerial photogrammetry

This paper proposes a framework for rapid seismic risk assessment of bridges using aerial photogrammetric surveys conducted by Unmanned Aerial Vehicles (UAVs). First, the data acquisition process for the photogrammetric 3D reconstruction of an asset and the subsequent procedure for computer-vision-based automatic extraction of visible geometric features are presented. Then, the extracted features are combined in the structural models to perform a seismic risk assessment in terms of capacity-to-demand ratios. Uncertainties are related to the material and geometric hidden variables. Monte Carlo simulation is performed, assuming uniform (uninformed) distributions for the input variables affected by epistemic uncertainty. The ranges of such distributions are estimated based on engineering judgment and knowledge of construction practices. The analysis provides an estimate of the epistemic uncertainties of the capacity-to-demand ratios, with limited available information obtained from UAV aerial photogrammetry. The feasibility and applicability of the proposed framework are demonstrated through a case study of a simply supported bridge in the Italian highway network. The 3D reconstruction process is validated by comparing the aerial survey with a laser scanner survey. The seismic risk of the selected bridge is assessed using the geometric information obtained from the UAV aerial photogrammetric survey. Finally, the paper discusses the applicability of the proposed methodology for bridge management purposes in an automated framework and at network scale.

Determining the geodetic mass balance of the Znosko glacier (King George Island, Antarctica) using an unmanned aerial vehicle

ABSTRACT In the last decade, unmanned aerial vehicles (UAVs) have been used for scientific research specially for glaciological applications in Antarctica. In the study an UAV was used to detect changes in Znosko glacier surface, map the glacier contour, snow line and estimate the geodetic mass balance. Znosko glacier (ZG) located in King George Island (KGI), Antarctic Peninsula has an estimated total area of 1.77 km2 (January 2020), a length of 1.9 km and maximum elevation of 300 metres above sea level (m a.s.l.). The aerial photogrammetric survey was carried out in two field campaigns (austral summer 2019 and 2020) during the XXVI and XXVII Peruvian Antarctic Operation using a Quadcopter for image acquisition. Our findings reveal a negative geodetic mass balance for the periods 2019–2012, 2020–2019 and 2020–2012 with −15.25, −2.76 and −17.97 metre water equivalent (m w.e.) respectively. Analysis of these datasets confirm a mass loss with a heterogeneous pattern between accumulation and ablation zone. Furthermore, glacier outlines reveal that ZG front has lost approximately 3% of its area between 2012 and 2020 by calving effect.

Robustness evaluation of a steel bridge in the district of Potenza (Italy)

In the current paper the Pastorella bridge in Lauria (district of Potenza) has been investigated. Firstly, considering the inaccessibility of the bridge with the exclusion of the main deck as a walkaway, an aerial photogrammetric survey with a drone has been done for the acquisition of geometric data. Secondly, a three-dimensional modelling of the bridge in FEM environment has been carried out. Based on the corrosion level detected in the bridge structure, forecasts about the progress of the corrosion damage during the whole lifetime of the bridge have also been made considering appropriate thickness reduction of structural elements based on literature provisions. Therefore, other than studying the intact bridge, four different corrosion scenarios have been considered: 1) corroded upper deck elements, 2) corroded lower chord elements; 3) corroded main diagonals and 4) corroded vertical members. On these FEM models push-down and linear dynamic analyses have been performed, so to know the health state of the bridge in terms of robustness for different corrosion levels.

Similarity Analysis between Contour Lines by Remotely Piloted Aircraft and Topography Using Hausdorff Distance: Application on Contour Planting

Contour planting minimizes soil degradation, making agricultural production more sustainable. Currently, geotechnologies can provide more precise and fast data from relief than rudimentary data acquisition for agricultural management. Thus, the objective of this work was to analyze the similarities between contour lines from topography and Remotely Piloted Aircraft, using the Hausdorff distance algorithm. This study was carried out in the period between January 2020 and November 2021 in four localities in the State of Rio de Janeiro, Brazil: two areas located in the municipality of Bom Jardim and two areas in the municipality of Seropédica. Data were acquired through a conventional topographic survey and an aerial photogrammetric survey by Remotely Piloted Aircraft. From the acquired field data for the studied areas, the Digital Elevation Models were generated with a spatial resolution of 0.20 m and the contour lines with an equidistance of one meter. The contour lines obtained by both techniques were superimposed and their similarity was verified using the Hausdorff distance. The results show that there was a better similarity among the contour lines in areas with a very rugged relief than in a smooth relief. Also, the lowest altimetric differences observed in the Digital Elevation Models were associated with the smallest Hausdorff distance. These adjustments correspond, respectively, to the segments between the contour lines with the best and the worst individual similarity for each area. We observed that the similarity between the contour lines from topography and RPA yielded slope differences lower than 6.1% for at least 95% of all studied areas. The Hausdorff distance analysis allowed us to conclude that contour planting can be performed from data obtained via Remotely Piloted Aircraft, provided that vertical accuracy analysis controls the quality of the Digital Elevation Models.

Understanding the retreat of the Jurassic Cantabrian coast (N. Spain): Comprehensive monitoring and 4D evolution model of the Tazones Lighthouse landslide

Forecasting coastal dynamics and sea cliff retreat under different sea level rise scenarios requires a good understanding of the conditioning factors and their relative contribution to cliff stability. The so-called Jurassic Cantabrian Coast extends along 76 km of the coastline of the Asturias region (N Spain) and is well-known worldwide due to its paleontological heritage, in particular the presence of dinosaur remains and footprints. The abundance of stratigraphic, paleontological and tectonic studies contrasts with the scarcity of studies focused on the stability of this rocky coastline where cliffs predominate, sometimes exceeding 120 m in height. In fact, evidence of current and recent instability processes can be observed along the entire coastline. In this regard, continuous monitoring is crucial to understand ongoing instabilities in rocky coastlines, as in these settings some instabilities might initiate as slow movements that induce subtle topographic changes whose detection from either satellite or aerial imagery is problematic due to the spatial and temporal resolutions. This contribution presents a 4D evolution model of a key site, the Tazones Lighthouse landslide, located on the Cantabrian Coast of Asturias (N Spain), which affects subvertical rocky cliffs sculpted in the Jurassic bedrock made of alternating sandstone and marl. A high resolution multiapproach methodology was developed in order to understand its structure and kinematic characteristics, including: i) interpretation of aerial photographs and unmanned aerial photogrammetric surveys (UAV); ii) 22 monthly monitoring campaigns by total station; iii) 5 manual boreholes; iv) geomechanical characterization of the cliff bedrock; v) geomorphological evidence mapping; vi) analysis of landscape deformations obtained from UAV; and vii) precipitation, soil moisture and significant wave height (Hs) data analysis. The results show that the slope evolves by means of a complex-type mass movement, which combines translational and sliding mechanisms, and occupies tens of thousands of square meters. DTM and fieldwork analysis indicate that mass movement is mainly controlled by bedrock discontinuities (S0, 360/15-17; J1, 262/85; J2 166/75). The most important accelerations of slope movement correlate very well with rainfall, soil moisture and waves. Thus, the largest displacements occurring in January and October–November 2019, coincide with 2 periods of storms (maximum 24-h rainfall of 64.5 mm and 82.1 mm and maximum Hs of 6.54 and 9.09, respectively) and soil moisture values above 90%. Half of the markers moved more than 1 m and one of them exceeded 15 m. The 4D model obtained after the interpretation of the Tazones Lighthouse slope whole dataset, allows an understanding of how the surrounding cliffs have evolved in the past, fundamental to predicting their future behaviour.

Toppling of a Trona Pinnacles Spire following the Mw 5.5 Ridgecrest Aftershock of June 2020

AbstractThe 2019 Mw 7.1 Ridgecrest California earthquake rupture passed within 4 km of the Trona Pinnacles, a large group of tufa rock pillars. Reconnaissance following the Ridgecrest mainshock documented fresh damage to several of the Pinnacles. Repeated aerial photogrammetric surveys also documented damage during subsequent aftershocks. Here, we describe the photogrammetric data with emphasis on a specific rock spire that toppled during an Mw 5.5 aftershock. We calculate the volumes of the intact spire and of its subsequent debris. To explore the utility of the pinnacles as fragile geologic features for constraining past earthquake shaking intensity, we calculate the quasi static, horizontal acceleration required to break the spire at its base. We also examine the response of this feature to observed shaking using a dynamic model of the spire. In this case, we find that the quasi-static estimate provides a conservative maximum constraint on fragility. The dynamic model of the spire suggests that shaking during the Mw 7.1 mainshock likely generated tensile stresses in excess of the spire’s bulk strength, thereby making it vulnerable to collapse in subsequent aftershocks.

ПРИМЕНЕНИЕ БЕСПИЛОТНЫХ ЛЕТАТЕЛЬНЫХ АППАРАТОВ ПРИ МАРКШЕЙДЕРСКОМ ОБЕСПЕЧЕНИИ СЪЕМКИ ЛЕСНОГО ФОНДА

Nowadays, the surveyor has at its disposal a wide range of instrument park, which allows you to achieve the engineering goals set in the survey support of mining facilities. Unmanned technologies are gaining an increasing sphere of surveying measurements, which lead to minimal participation of a specialist in field work, but require a more classified approach to off-site processing. However, it is worth noting that each mining enterprise, for example, such as a quarry, having an exclusive boundary of work, called a license area, in its contour may have a forest area, which is an object that causes cer-tain difficulties for surveying support. This article tells about the possibility of using a short-range un-manned UAVs for surveying the forest area, as well as analyzing the result obtained and determining its compliance with engineering requirements when obtaining an up-to-date topographic plan of the area. To determine the possibility of using unmanned technology in mine surveying of a forest, theo-retical and experimental research methods will be used, including a significant set of empiricals, the mathematical processing of which will help to reveal the correlation dependences of aerial photo-grammetric survey parameters for the optimal use of a geodetic quadcopter. The result of the study given in this article will be a provision on the possibility of using unmanned technologies for aerial photogrammetric survey of a forest land, correlation dependences of flight parameters and their results will be determined, the derivatives of which will be topographic plans, the comparison of which will be carried out with plans, created by the classical method.

Geological-geotechnical risk mapping of gravitational mass movements in an urban area in Colombo, Brazil

This work presents a geological-geotechnical risk map of gravitational mass movements and a susceptibility map to shallow translational slides to Vila Nova community, located in the municipality of Colombo, Brazil. The first map was created through a qualitative mapping methodology and the second one was elaborated using a deterministic method of slope stability. An aerial photogrammetric survey with UAV technology was performed, as well as field reconnaissance, laboratory testing, and geoprocessing techniques. Seven slope failures were identified as well as a range of other evidences of instability associated with the predisposition of the terrain to erosive and gravitational movements linked to human intervention without urban planning and engineering techniques. Moreover, the qualitative and quantitative analyses pointed out that 13% to 9% of the study area, respectively, are in a very high-risk condition for landslides. Thus, the resulting cartographic products are presented as an important technical contribution for landslide risk management as well as land use planning for reducing the geotechnical problems faced on site.

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

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.

Extraction of Roof Planes from Different Point Clouds Using RANSAC Algorithm

Solar energy is a renewable energy source directly from sunlight and its production depends on roof characteristics such as roof type and size. In solar potential analysis, the main purpose is to determine the suitable roofs for the placement of solar panels. Hence, roof plane detection plays a crucial role in solar energy assessment. In this study, a detailed comparison was presented between aerial photogrammetry data and LIDAR data for roof plane recognition applying RANSAC (Random Sample Consensus) algorithm. RANSAC algorithm was performed to 3D-point clouds obtained by both LIDAR (Laser Ranging and Detection) and aerial photogrammetric survey. In this regard, solar energy assessment from the results can be applied. It is shown that, the RANSAC algorithm detects building roofs better on the point cloud data acquired from airborne LIDAR regarding completeness within model, since aerial photogrammetric survey provides noisy data in spite of its high-density data. This noise in the source data leads to deformations in roof plane detection. The study area of the project is the campus of Istanbul Technical University. Accuracy information of the roof extraction of three different buildings are presented in tables.

LIDAR AND PHOTOGRAMMETRIC DATASETS INTEGRATION USING SUB-BLOCK OF IMAGES

Abstract. Imagery and Lidar datasets have been used frequently to extract geoinformation. Datasets in the same mapping or geodetic frame is a fundamental condition for this application. Nowadays, Direct Sensor Orientation (DSO) can be considered as a mandatory technology to be used in the aerial photogrammetric survey. Although the DSO provides a high degree of automation process due to the GNSS/INS technologies, the accuracies of the obtained results from the imagery and Lidar surveys are dependent on the quality of a group of parameters that models accurately the user conditions of the system at the moment the job is performed. This paper shows the study that was performed to improve the tridimensional accuracies of the aerial imagery and Lidar datasets integration using the 3D photogrammetric intersection of single models (pairs of images) with Exterior Orientation Parameters (EOP) estimated from DSO. A Bundle Adjustment with additional parameters (BBA) of a small sub-block of images is used to refine the Interior Orientation Parameters (IOP) and EOP in the job condition. In the 3D photogrammetric intersection experiments using the proposed approach, the horizontal and vertical accuracies, estimated by the Root Mean Square Error (RMSE) of the 3D discrepancies from the Lidar checkpoints, increased around of 25% and 75% respectively.

CNN SEMANTIC SEGMENTATION TO RETRIEVE PAST LAND COVER OUT OF HISTORICAL ORTHOIMAGES AND DSM: FIRST EXPERIMENTS

Abstract. Images from archival aerial photogrammetric surveys are a unique and relatively unexplored means to chronicle 3D land-cover changes occurred since the mid 20th century. They provide a relatively dense temporal sampling of the territories with a very high spatial resolution. Thus, they offer time series data which can answer a large variety of long-term environmental monitoring studies. Besides, they are generally stereoscopic surveys, making it possible to derive 3D information (Digital Surface Models). In recent years, they have often been digitized, making them more suitable to be considered in automatic analyses processes. Some photogrammetric softwares make it possible to retrieve their geometry (pose and camera calibration) and to generate corresponding DSM and orthophotomosaic. Thus, archival aerial photogrammetric surveys appear as being a powerful remote sensing data source to study land use/cover evolution over the last century. However, several difficulties have to be faced to be able to use them in automatic analysis processes. Indeed, surveys available on a study area can exhibit very different characteristics: survey pattern, focal, spatial resolution, modality (panchromatic, colour, infrared…). Planimetric and altimetric accuracies of derived products strongly depend on these characteristics. Thus, analysis processes have to cope with these uncertainties. Another important gap states in the lack of training data. Deep learning methods and especially Convolutional Neural Networks (CNN) are at present the most efficient semantic segmentation methods as long as a sufficient training dataset is available. However, temporal gaps can be very important between existing available databases and archival data. In this study, two custom variants of simple yet effective U-net - Deconv-Net inspired DL architectures are developed to process ortho-image and DSM based information. They are then trained out of a groundtruth derived out of a recent database to process archival datasets.

A 54-year record of changes at Chalaati and Zopkhito glaciers, Georgian Caucasus, observed from archival maps, satellite imagery, drone survey and ground-based investigation

Individual glacier changes are still poorly documented in the Georgian Caucasus. In this paper, the change of Chalaati and Zopkhito glaciers in Georgian Caucasus has been studied between 1960 and 2014. Glacier geometries are reconstructed from archival topographic maps, Corona and Landsat images, along with modern field surveys. For the first time in the Georgian Caucasus aerial photogrammetric survey of both glacier termini was performed (2014) using a drone or Unmanned Aerial Vehicle, where high-resolution orthomosaics and digital elevation models were produced. We show that both glaciers have experienced area loss since 1960: 16.2±4.9 per cent for Chalaati Glacier and 14.6±5.1 per cent for Zopkhito Glacier with corresponding respective terminus retreat by ~675 m and ~720 m. These were accompanied by a rise in the equilibrium line altitudes of ~35 m and ~30 m, respectively. The glacier changes are a response to regional warming in surface air temperature over the last half century. We used a long-term temperature record from the town of Mestia and short-term meteorological observations at Chalaati and Zopkhito glaciers to estimate a longer-term air temperature record for both glaciers. This analysis suggests an increase in the duration of the melt season over the 54-year period, indicating the importance of summertime air temperature trends in controlling glacier loss in the Georgian Caucasus. We also observed supra-glacial debris cover increase for both glaciers over the last half century: from 6.16±6.9 per cent to 8.01±6.8 per cent for Chalaati Glacier and from 2.80±6.3 per cent to 8.53±5.7 per cent for Zopkhito Glacier.

Comparative evaluation of wearable devices for measuring elevation gain in mountain physical activities

The aim of this article is to examine the validity of elevation gain measures in mountain activities, such as hiking and mountain running, using different wearable devices and post-processing procedures. In particular, a total of 202 efforts were recorded and evaluated using three standard devices: GPS watch, GPS watch with barometric altimeter, and smartphone. A benchmark was based on orthorectified aerial photogrammetric survey conducted by the Chilean Air Force. All devices presented considerable elevation gain measuring errors, where the barometric device consistently overestimated elevation gain, while the GPS devices consistently underestimated elevation gain. The incorporation of secondary information in the post-processing can substantially improve the elevation gain measuring accuracy independently of the device and altitude measuring technology, reducing the error from −5% to −1%. These results could help coaches and athletes correct elevation gain estimations using the proposed technique, which would serve as better estimates of physical workload in mountain physical activities.

UAV photogrammetry, infrared thermography and GPR for enhancing structural and material degradation evaluation of the Roman masonry bridge of Ponte Lucano in Italy

This paper presents a case study regarding the cooperative use of non-destructive contactless diagnostic investigations as a tool to aid and assist the degradation evaluation of an iconic Roman masonry bridge: Ponte Lucano in Tivoli, Italy. Specifically, unmanned aerial photogrammetric surveys are considered to perform detailed visual inspections and obtain a geometrical 3D model; infrared thermography analyses are carried out to characterize the thermal surface map of the structure detecting anomalies related to material degradation, such as the presence of humidity; ground penetrating radar investigations are performed to improve knowledge of the bridge subsurface structure. The results of the analyses demonstrate that the integration of mentioned diagnostic tools provides information regarding the degradation state of the stones and its causes, as well as regarding the evolution of the structure from its construction up to the present configurations.