Showing papers on "Photogrammetry published in 2023"

Trueness and precision of complete-arch photogrammetry implant scanning assessed with a coordinate-measuring machine

Abstract: Statement of problem Photogrammetry technology has been used for the digitalization of multiple dental implants, but its trueness and precision remain uncertain. Purpose The purpose of this in vitro investigation was to compare the accuracy (trueness and precision) of multisite implant recordings between the conventional method and a photogrammetry dental system. Material and methods A definitive cast of an edentulous maxilla with 6 implant abutment replicas was tested. Two different recording methods were compared, the conventional technique and a photogrammetry digital scan (n=10). For the conventional group, the impression copings were splinted to an additively manufactured cobalt-chromium metal with autopolymerizing acrylic resin, followed by recording the maxillary edentulous arch with an elastomeric impression using an additively manufactured open custom tray. For the photogrammetry group, a scan body was placed on each implant abutment replica, followed by the photogrammetry digital scan. A coordinate-measuring machine was selected to assess the linear, angular, and 3-dimensional discrepancies between the implant abutment replica positions of the reference cast and the specimens by using a computer-aided design program. The Shapiro-Wilk test showed that the data were not normally distributed. The Mann-Whitney U test was used to analyze the data (α=.05). Results The conventional group obtained an overall accuracy (trueness ±precision) value of 18.40 ±6.81 μm, whereas the photogrammetry group showed an overall scanning accuracy value of 20.15 ±25.41 μm. Significant differences on the discrepancies on the x axis (U=1380.00, P=.027), z axis (U=601.00, P<.001), XZ angle (U=869.00, P<.001), and YZ angle (U=788.00, P<.001) were observed when the measurements of the 2 groups were compared. Furthermore, significant 3-dimensional discrepancy for implant 1 (U=0.00, P<.001), implant 2 (U=0.00, P<.001), implant 3 (U=6.00, P<.001), and implant 6 (U=9.00, P<.001) were computed between the groups. Conclusions The conventional method obtained statistically significant higher overall accuracy values compared with the photogrammetry system tested, with a trueness difference of 1.8 μm and a precision difference of 18.6 μm between the systems. The conventional method transferred the implant abutment positions with a uniform 3-dimensional discrepancy, but the photogrammetry system obtained an uneven overall discrepancy among the implant abutment positions.

3D LiDAR and multi-technology collaboration for preservation of built heritage in China: A review

Abstract: In recent years, the technical application of 3D LiDAR has gradually expanded to the field of built heritage. 3D scanning, high-precision measurement, and reconstruction have enriched the methods of built heritage preservation and significantly improved the quality of heritage preservation in China. 3D LiDAR has broken through the limitations of a single technology application and played a greater role in the field of heritage preservation on different scales. Through the collaboration of multi-technology, such as 3D printing, digital mapping, internet of things, machine learning, intelligent sensors, close-range photogrammetry, infrared detection, stress wave tomography, material analysis, XR technology, reverse engineering, etc., 3D LiDAR shows its technological advantages on exploring the remote real-time monitoring and digitization of the built heritage, geological and environmental data collection, prediction of sedimentation, deformation monitoring, weather monitoring,system life cycle health detection, digital reproduction of built heritage for developing scientific problems and engineering practices such as building contour recognition, information feature matching, structural reinforcement and damaged component replacement. In addition, through the docking with GIS, HBIM, XR, and CIM, it provides fine digital models and high-precision data benchmarks which contribute to the heritage visual reproduction; and through the docking with 3Ds Max, SketchUp, and other modeling software, it has contributed to the renewal design of the built heritage, space optimization, and the scientificity and rationality of the heritage value evaluation. However, past technology applications also highlighted many problems such as limited recorded information, a large amount of data, high difficulty in collaboration, non-standardized and fragmented data, and difficulty in data mining and comprehensive utilization. There are still deficiencies in building a built heritage data backplane, and the development of a dynamic, three-dimensional, intelligent and refined heritage monitoring system, and further research is needed on these issues. This study reviews the previous academic progress and application of 3D LiDAR in the reconstruction of built heritage and multi-technology collaboration in the process of preservation, clarifies the current research hotspots and methods, the frontier issues of concern, and also clarifies the specific problems and challenges in the future.

Applying Geomatics Techniques for Documenting Heritage Buildings in Aswan Region, Egypt: A Case Study of the Temple of Abu Simbel

Abstract: It has recently become more popular to involve 3-D modeling and digital documentation in the conservation and restoration of heritage sites. The main objective of the current study is to develop a digital documentation process using laser scanning for Abu Simbel Temple, which is one of the most famous archaeological sites in Egypt. We focus on these techniques to replace traditional methods of building heritage documentation. To create the 3-D model with geographic coordinates and measure the rate of deformation, a precise geodetic network of five points was established around the temple. Then, 52 scans of the temple facade and its interior parts were taken using a Trimble TX6 laser scanner. This led to the creation of a 3-D digital model of the temple that includes geometric, structural, architectural, historical data, and non-engineering information (such as appearance, inscriptions, and material details). The 3-D point cloud model outputs exhibit a 6 mm spacing between the points with an error of 4 mm and a standard deviation of 5 mm. In addition, the temple’s virtual tour included 61 panoramic images. This virtual tour can help to increase heritage awareness, promote tourism, and aid in the future restoration of any parts vulnerable to damage.

The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy

Abstract: Abstract We provide a survey on the joint European research project “GeoMetre”, which explores novel technologies and their inclusion to existing surveying strategies to improve the traceability of geodetic reference frames to the SI definition of the metre. This work includes the development of novel distance meters with a range of up to 5 km, the realisation of optical multilateration systems for large structure monitoring at an operation distance of 50 m and beyond, and a novel strategy for GNSS-based distance determination. Different methods for refractivity compensation, based on classical sensors, on dispersion, on spectroscopic thermometry, and on the speed of sound to reduce the meteorological uncertainties in precise distance measurements, are developed further and characterised. These systems are validated at and applied to the novel European standard baseline EURO5000 at the Pieniny Kippen Belt, Poland, which was completely refurbished and intensely studied in this project. We use our novel instruments for a reduced uncertainty of the scale in the surveillance networks solutions for local tie measurements at space-geodetic co-location stations. We also investigate novel approaches like close-range photogrammetry to reference point determination of space-geodetic telescopes. Finally, we also investigate the inclusion of the local gravity field to consider the deviations of the vertical in the data analysis and to reduce the uncertainty of coordinate transformations in this complex problem.

A State-of-the-Practice Review of Three-Dimensional Laser Scanning Technology for Tunnel Distress Monitoring

Abstract: Tunnel distress occurs often. Tunnel leakage, segment dislocation, and section deformation seriously affect tunnel construction safety and normal operation. Currently, mainly the traditional monitoring technology is used in tunnel distress monitoring. This kind of technology has the problems of low monitoring efficiency, slow speed, inaccurate measuring points, and so on. With the development of science and technology, three-dimensional laser scanning monitoring technology (3D LSMT) has fast acquisition speed, a comprehensive monitoring range, and high acquisition accuracy. This review collected the world’s more advanced monitoring technologies, such as optical fiber sensing technology (OFST), photogrammetry (PT), and so on. Firstly, these technologies were introduced and compared with 3D LSMT. Then the theoretical basis of 3D LSMT was analyzed. Three-dimensional LSMT uses the captured high-density point cloud to extract the tunnel structure information and realizes the rapid processing of point cloud data through automated software. Finally, the use of 3D LSMT for segment dislocation, tunnel deformation, and seepage water was discussed and analyzed further to understand the status of 3D LSMT in tunnel monitoring and provide a reference for tunnel distress monitoring.

An Overview on Image-Based and Scanner-Based 3D Modeling Technologies

Abstract: Advances in the scientific fields of photogrammetry and computer vision have led to the development of automated multi-image methods that solve the problem of 3D reconstruction. Simultaneously, 3D scanners have become a common source of data acquisition for 3D modeling of real objects/scenes/human bodies. This article presents a comprehensive overview of different 3D modeling technologies that may be used to generate 3D reconstructions of outer or inner surfaces of different kinds of targets. In this context, it covers the topics of 3D modeling using images via different methods, it provides a detailed classification of 3D scanners by additionally presenting the basic operating principles of each type of scanner, and it discusses the problem of generating 3D models from scans. Finally, it outlines some applications of 3D modeling, beyond well-established topographic ones.

Application of photogrammetric methods for locating and tracking cetacean movements at sea

Abstract: Accurate measurements of the locations of surfacing cetaceans are important data for behavioural studies and sightings surveys. A system for tracking cetacean movements based on photogrammetric analysis of digital images has been developed and tested at sea. Radial distances from the ship to surfacing whales were calculated from video images by measuring the angle of dip between the whale and the horizon. Bearings were either measured from still images of reference points on the ship, from a magnetic bearing compass or from the bearing ring of stand-mounted binoculars. The system uses readily available equipment and can be operated by one person. Calibration tests were conducted to assess the accuracy of the system. Errors in distance measurement increased approximately linearly with distance. Under typical survey conditions, from a large vessel with an eye height of 18m, distances to whales could be measured with a root mean square error of 3.5%. A model was developed to enable corrections to be made for atmospheric refraction. This has implications for other studies using reticle binoculars. If refraction is not corrected then distance estimates will be negatively biased. Field trials of the system were conducted from several different types and sizes of vessel during studies of a number of different species. Results of these trials demonstrated that the system is a practical tool for fine-scale tracking of cetacean movements and could also be used on line transect surveys. The limitations of the system are the need for a clear horizon and difficulties, for some species, in obtaining suitable quality images of all surfacings. There is also a moderate overhead in increased analysis time. Advances in digital imaging technology are likely to solve many of the image quality problems in the future.

Assessment of Accuracy in Unmanned Aerial Vehicle (UAV) Pose Estimation with the REAL-Time Kinematic (RTK) Method on the Example of DJI Matrice 300 RTK

Abstract: The growing possibilities offered by unmanned aerial vehicles (UAV) in many areas of life, in particular in automatic data acquisition, spur the search for new methods to improve the accuracy and effectiveness of the acquired information. This study was undertaken on the assumption that modern navigation receivers equipped with real-time kinematic positioning software and integrated with UAVs can considerably improve the accuracy of photogrammetric measurements. The research hypothesis was verified during field measurements with the use of a popular Enterprise series drone. The problems associated with accurate UAV pose estimation were identified. The main aim of the study was to perform a qualitative assessment of the pose estimation accuracy of a UAV equipped with a GNSS RTK receiver. A test procedure comprising three field experiments was designed to achieve the above research goal: an analysis of the stability of absolute pose estimation when the UAV is hovering over a point, and analyses of UAV pose estimation during flight along a predefined trajectory and during continuous flight without waypoints. The tests were conducted in a designated research area. The results were verified based on direct tachometric measurements. The qualitative assessment was performed with the use of statistical methods. The study demonstrated that in a state of apparent stability, horizontal deviations of around 0.02 m occurred at low altitudes and increased with a rise in altitude. Mission type significantly influences pose estimation accuracy over waypoints. The results were used to verify the accuracy of the UAV’s pose estimation and to identify factors that affect the pose estimation accuracy of an UAV equipped with a GNSS RTK receiver. The present findings provide valuable input for developing a new method to improve the accuracy of measurements performed with the use of UAVs.

New Approach for Photogrammetric Rock Slope Premonitory Movements Monitoring

Abstract: An automated, fixed-location, continuous time-lapse camera system was developed to analyze the existence of rockfall precursory movements and quantify volume changes after detachments. It was implemented to monitor the basaltic formation on which Castellfollit de la Roca village is built. Due to the geometrical conditions of the area, the camera system consists of three digital cameras managed by a control unit that contains a Raspberry Pi 4 microprocessor. Images taken every day are sent to a server for processing. A workflow has been developed to work with a set of images with an irregular time interval to detect precursor movement. The first step consists of matching the images with a reference master image and filtering the vegetation to improve the process using a mask obtained by a green leaf index (GLI) index. Then, the adjusted images are used for a forward-backward correlation process carried out to detect movements. If movement is detected, a 3D model is built using structure from motion (SfM) to quantify the movements. The system has been working since September 2021. During this period, movements from 0.01 to 0.5 m and several rockfalls of a small volume have been detected.

A Simple Way to Reduce 3D Model Deformation in Smartphone Photogrammetry

Abstract: Recently, the term smartphone photogrammetry gained popularity. This suggests that photogrammetry may become a simple measurement tool by virtually every smartphone user. The research was undertaken to clarify whether it is appropriate to use the Structure from Motion—Multi Stereo View (SfM-MVS) procedure with self-calibration as it is done in Uncrewed Aerial Vehicle photogrammetry. First, the geometric stability of smartphone cameras was tested. Fourteen smartphones were calibrated on the checkerboard test field. The process was repeated multiple times. These observations were found: (1) most smartphone cameras have lower stability of the internal orientation parameters than a Digital Single-Lens Reflex (DSLR) camera, and (2) the principal distance and position of the principal point are constantly changing. Then, based on images from two selected smartphones, 3D models of a small sculpture were developed. The SfM-MVS method was used, with self-calibration and pre-calibration variants. By comparing the resultant models with the reference DSLR-created model it was shown that introducing calibration obtained in the test field instead of self-calibration improves the geometry of 3D models. In particular, deformations of local concavities and convexities decreased. In conclusion, there is real potential in smartphone photogrammetry, but it also has its limits.

Monitoring Mining Surface Subsidence with Multi-Temporal Three-Dimensional Unmanned Aerial Vehicle Point Cloud

Abstract: Long-term and high-intensity coal mining has led to the increasingly serious surface subsidence and environmental problems. Surface subsidence monitoring plays an important role in protecting the ecological environment of the mining area and the sustainable development of modern coal mines. The development of surveying technology has promoted the acquisition of high-resolution terrain data. The combination of an unmanned aerial vehicle (UAV) point cloud and the structure from motion (SfM) method has shown the potential of collecting multi-temporal high-resolution terrain data in complex or inaccessible environments. The difference of the DEM (DoD) is the main method to obtain the surface subsidence in mining areas. However, the obtained digital elevation model (DEM) needs to interpolate the point cloud into the grid, and this process may introduce errors in complex natural topographic environments. Therefore, a complete three-dimensional change analysis is required to quantify the surface change in complex natural terrain. In this study, we propose a quantitative analysis method of ground subsidence based on three-dimensional point cloud. Firstly, the Monte Carlo simulation statistical analysis was adopted to indirectly evaluate the performance of direct georeferencing photogrammetric products. After that, the operation of co-registration was carried out to register the multi-temporal UAV dense matching point cloud. Finally, the model-to-model cloud comparison (M3C2) algorithm was used to quantify the surface change and reveal the spatio-temporal characteristics of surface subsidence. In order to evaluate the proposed method, four periods of multi-temporal UAV photogrammetric data and a period of airborne LiDAR point cloud data were collected in the Yangquan mining area, China, from 2020 to 2022. The 3D precision map of a sparse point cloud generated by Monte Carlo simulation shows that the average precision in X, Y and Z directions is 44.80 mm, 45.22 and 63.60 mm, respectively. The standard deviation range of the M3C2 distance calculated by multi-temporal data in the stable area is 0.13–0.19, indicating the consistency of multi-temporal photogrammetric data of UAV. Compared with DoD, the dynamic moving basin obtained by the M3C2 algorithm based on the 3D point cloud obtained more real surface deformation distribution. This method has high potential in monitoring terrain change in remote areas, and can provide a reference for monitoring similar objects such as landslides.

Using UAS-Aided Photogrammetry to Monitor and Quantify the Geomorphic Effects of Extreme Weather Events in Tectonically Active Mass Waste-Prone Areas: The Case of Medicane Ianos

Abstract: Extreme weather events can trigger various hydrogeomorphic phenomena and processes including slope failures. These shallow instabilities are difficult to monitor and measure due to the spatial and temporal scales in which they occur. New technologies such as unmanned aerial systems (UAS), photogrammetry and the structure-from-motion (SfM) technique have recently demonstrated capabilities useful in performing accurate terrain observations that have the potential to provide insights into these geomorphic processes. This study explores the use of UAS-aided photogrammetry and change detection, using specialized techniques such as the digital elevation model (DEM) of differences (DoD) and cloud-to-cloud distance (C2C) to monitor and quantify geomorphic changes before and after an extreme medicane event in Myrtos, a highly visited touristic site on Cephalonia Island, Greece. The application demonstrates that the combination of UAS with photogrammetry allows accurate delineation of instabilities, volumetric estimates of morphometric changes, insights into erosion and deposition processes and the delineation of higher-risk areas in a rapid, safe and practical way. Overall, the study illustrates that the combination of tools facilitates continuous monitoring and provides key insights into geomorphic processes that are otherwise difficult to observe. Through this deeper understanding, this approach can be a stepping stone to risk management of this type of highly-visited sites, which in turn is a key ingredient to sustainable development in high-risk areas.

Visiting Heritage Sites in AR and VR

Abstract: Advances in digitization technologies have made possible the digitization of entire archaeological sites through a combination of technologies, including aerial photogrammetry, terrestrial photogrammetry, and terrestrial laser scanning. At the same time, the evolution of computer algorithms for data processing and the increased processing power made possible the combination of data from multiple scans to create a synthetic representation of large-scale sites. Finally, post-processing techniques and the evolution of computer and mobile GPUs and game engines have made possible the exploitation of digitization outcomes to further scientific study and historical preservation. This route was opened by the gaming industry. In terms of research, the exploitation of these new assets in conjunction with new visual rendering technologies, such as virtual and augmented reality, can create new dimensions for education and leisure. In this paper, we explore the usage of large-scale digitization of a heritage site to create a unique virtual visiting experience that can be accessed offline in VR and AR and on-site when visiting the archaeological site.

Helicopter-borne RGB orthomosaics and photogrammetric digital elevation models from the MOSAiC Expedition

Abstract: Abstract The Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition took place between October 2019 and September 2020 giving the rare opportunity to monitor sea-ice properties over a full annual cycle. Here we present 24 high-resolution orthomosaics and 14 photogrammetric digital elevation models of the sea-ice surface around the icebreaker RV Polarstern between March and September 2020. The dataset is based on >34.000 images acquired by a helicopter-borne optical camera system with survey flights covering areas between 1.8 and 96.5 km 2 around the vessel. Depending on the flight pattern and altitude of the helicopter, ground resolutions of the orthomosaics range between 0.03 and 0.5 m. By combining the photogrammetric products with contemporaneously acquired airborne laser scanner reflectance measurements selected orthomosaics could be corrected for cloud shadows which facilitates their usage for sea-ice and melt pond classification algorithms. The presented dataset is a valuable data source for the interdisciplinary MOSAiC community building a temporal and spatially resolved baseline to accompany various remote sensing and in situ research projects.

Combination of terrestrial laser scanning and UAV photogrammetry for 3D modelling and degradation assessment of heritage building based on a lighting analysis: case study—St. Adalbert Church in Gdansk, Poland

Abstract: 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.

A co-learning method to utilize optical images and photogrammetric point clouds for building extraction

Abstract: Although deep learning techniques have brought unprecedented accuracy to automatic building extraction, several main issues still constitute an obstacle to effective and practical applications. The industry is eager for higher accuracy and more flexible data usage. In this paper, we present a co-learning framework applicable to building extraction from optical images and photogrammetric point clouds, which can take the advantage of 2D/3D multimodality data. Instead of direct information fusion, our co-learning framework adaptively exploits knowledge from another modality during the training phase with a soft connection, via a predefined loss function. Compared to conventional data fusion, this method is more flexible, as it is not mandatory to provide multimodality data in the test phase. We propose two types of co-learning: a standard version and an enhanced version, depending on whether unlabeled training data are employed. Experimental results from two data sets show that the methods we present can enhance the performance of both image and point cloud networks in few-shot tasks, as well as image networks when applying fully labeled training data sets.

Noncontact Sensing Techniques for AI-Aided Structural Health Monitoring: A Systematic Review

Abstract: Engineering structures and infrastructure continue to be used despite approaching or having reached their design lifetime. While contact-based measurement techniques are challenging to implement at a large scale and provide information at discrete locations only, noncontact methods are more user-friendly and offer accurate, robust, and continuous spatial information to quantify the structural conditions of the targeted systems. Advancements in optical sensors and image-processing algorithms increased the applicability of image-based noncontact techniques, such as photogrammetry, infrared thermography, and laser imaging for structural health monitoring (SHM). In addition, with the incorporation of artificial intelligence (AI) algorithms, the assessment process is expedited and made more efficient. This article summarizes the efforts made in the last five years to leverage AI-aided noncontact sensing techniques for applications in SHM with an emphasis on image-based methods. Future directions to advance AI-aided image-based sensing techniques for SHM of engineering structures are also discussed.

Fft-based filtering approach to fuse photogrammetry and photometric stereo 3d data

Abstract: Abstract. Image-based 3D reconstruction has been successfully employed for micro-measurements and industrial quality control purposes. However, obtaining a highly-detailed and reliable 3D reconstruction and inspection of non-collaborative surfaces is still an open issue. Photometric stereo (PS) offers the high spatial frequencies of the surface, but the low frequency is erroneous due to the mathematical model's assumptions and simplifications on how light interacts with the object surface. Photogrammetry, on the other hand, gives precise low-frequency information but fails to utilize high frequencies. As a result, in this research, we present a fusion strategy in Fourier domain to replace the low spatial frequencies of PS with the corresponding photogrammetric frequencies in order to have correct low frequencies while maintaining high frequencies from PS. The proposed method was tested on three different objects. Different cloud-to-cloud comparisons were provided between reference data and the 3D points derived from the proposed method to evaluate high and low frequency information. The obtained 3D findings demonstrated how the proposed methodology generates a high-detail 3D reconstruction of the surface topography (below 20 µm) while maintaining low-frequency information (0.09 µm on average for three different testing objects) by fusing photogrammetric and PS depth data with the proposed FFT-based method.

Relief Modeling in the Restoration of Extractive Activities Using Drone Imagery

Abstract: In the field of mine engineering, a cross-section topographic survey is usually carried out to perform volumetric calculations of earth movement in order to restore areas affected by extractive activities. Nowadays, Remote Sensing and Geographical Information System (GIS) technologies make it possible to perform the same work by using indirect methods such as images obtained by photogrammetric flights. In this context, Unmanned Aerial Systems (UAS) are considered a very convenient option to develop mapping projects in short periods of time and to provide quality geospatial information such as Digital Elevation Models (DEM) and orthophotos of centimetric spatial resolution. In the present study, this approach has been applied in a gravel extraction area to obtain data for estimating the filling volume of material required for the restoration of the relief (DEM(r)). The estimation of the DEM(r) is later used to calculate a difference of height values (DEM(r)-DEM) that will serve as a variable in the basic operation of volume calculation. The novelty of the presented method is the simulation of a relief adapted to the surrounding morphology, including the derived channel network and the visibility impact, improving what would be a simple clogging. Likewise, the generation of 3D models allows visualizing a new morphological structure of the relief. The proposed approach, based on GIS tools, allows analyzing water flow connectivity integration of the DEM(r) with the environment and estimating potential landscape impacts from the main focuses of a visual basin, both of which are key aspects of restoration modeling that are not always properly addressed.

Evaluating Characteristics of an Active Coastal Spreading Area Combining Geophysical Data with Satellite, Aerial, and Unmanned Aerial Vehicles Images

Abstract: The northern region of the Maltese archipelago is experiencing lateral spreading landslide processes. This region is characterized by cliffs with a hard coralline limestone outcropping layer sitting on a thick layer of clay. Such a geological configuration causes coastal instability that results in lateral spreading which predispose to rockfalls and topplings all over the cliff slopes. The aim of this research was to develop a methodology for evaluating cliff erosion/retreat using the integration of geomatics and geophysical techniques. Starting from a 3D digital model of the Selmun promontory, generated by unmanned aerial vehicle (UAV) photogrammetry, it was possible to map the fractures and conduct geophysical measurements such as electrical resistivity tomography and ground penetrating radar for the identification and mapping of vertical fractures affecting the hard coralline limestone plateau, and to create a 3D geological model of the study area. In addition to this, high-accuracy orthophotos from UAV that were captured between 1957 and 2021 were georeferenced into a GIS and compared to aerial and satellite images. The movement and evolution of boulders and cracks in rocks were then vectorized to highlight, track and quantify the phenomenon through time. The results were used to derive a qualitative assessment of the coastal variations in the geometric properties of the exposed discontinuity surfaces to evaluate the volumes and the stop points of the observed rockfalls. The outcomes of this research were finally imported in a GIS which offers an easy approach for the collection and processing of coastal monitoring data. In principle, such a system could help local authorities to address social, economic and environmental issues of pressing importance as well as facilitate effective planning in view of a risk mitigation strategy.

Digital Twins and Cultural Heritage Preservation: A Case Study of Best Practices and Reproducibility in Chiesa dei SS Apostoli e Biagio

Abstract: The use of digital twin technologies to preserve cultural heritage has become increasingly common over the past two decades. Evolving from the use of virtual environments (VE) and digital reconstructions that required multiple phases of workflow and multiple software applications and various hardware to output a useable experience to the immediacy of 3D artificial intelligence (AI) generative content and the latest generation of photogrammetric scanning, non-specialists are now able to more easily create digital twins. At the same time, the destruction of cultural heritage has accelerated due to geopolitical instability, seen in examples such as the invasion of Ukraine by Russia (2022). Even with advances in user-friendly and commercially available technologies, digital art history and the digital humanities are in a race against time to train and equip enough individuals onsite to create digital twins before more irreplaceable cultural artifacts and sites are lost to natural disasters, accelerated by climate change, or through armed conflict. However, there remain no international standards for methodological reproducibility and the techniques used currently by many scholars include specialized training and knowledge. As such, this paper presents a case study that addresses reproducibility and explainability in the digital humanities through a detailed workflow of the creation of a digital twin of Chiesa dei SS Apostoli e Biagio in Florence, Italy. A model is presented that is scalable and leverages widely available, user-friendly 360 cameras and photogrammetry with LiDAR to capture cultural heritage sites with best practices on how to quickly and effectively train non-specialists to create site-specific digital twins of a variety of cultural heritage structures.

A critical comparison of interpolation techniques for digital terrain modelling in mining

Abstract: Digital modelling of a surface is crucial for Earth science and mining applications for many reasons. These days, high-tech digital representations are used to produce a high-fidelity topographic surface in the form of a digital terrain model (DTM). DTMs are created from 2D data-points collected by a variety of techniques such as traditional ground surveying, image processing, LiDAR, radar, and global positioning systems. At the points for which data is not available, the heights need to be interpolated or extrapolated from the points with measured elevations. There are several interpolation/extrapolation techniques available, which may be categorized based on criteria such as area size, accuracy or exactness of the surface, smoothness, continuity, and preciseness. In this paper we examine these DTM production methods and highlight their distinctive characteristics. Real data from a mine site is used, as a case study, to create DTMs using various interpolation techniques in Surfer® software. The significant variation in the resulting DTMs demonstrates that developing a DTM is not straightforward and it is important to choose the method carefully because the outcomes depend on the interpolation techniques used. In mining instances, where volume estimations are based on the produced DTM, this can have a significant impact. For our data-set, the natural neighbour interpolation method made the best predictions (R2 = 0.969, β = 0.98, P < 0.0001).

Review of Photogrammetric and Lidar Applications of UAV

Abstract: Using Unmanned Aerial Vehicles (UAVs) combined with various sensors brings the benefits associated with fast, automatic, and contactless spatial data collection with high resolution and accuracy. The most frequent application is the possibility of effectively creating spatial models based on photogrammetric and lidar data. This review analyzes the current possibilities of UAVs. It provides an overview of the current state of the art and research on selected parameters regarding their history and development, classification, regulation, and application in surveying with creating spatial models. Classification and regulation are based on national sources. The importance and usability of this review are also carried out by analyzing the UAV application with selected photogrammetric and lidar sensors. The study explores and discusses results achieved by many authors in recent years, synthesizing essential facts. By analyzing the network of co-occurring High-Frequency Words, in addition, we visualized the importance of the primary keyword UAV in the context of other keywords in the literary sources processed.

The Ribadeo I Wreck—Multi-Year Photogrammetric Survey of a Spanish Galleon of the Second Armada

Abstract: There are multiple approaches to bridging the gap between the relatively new world of three-dimensional survey and so-called reality-capture with traditional recording conventions and archaeological interpretative processes, challenges that have been encountered during the various fieldwork campaigns undertaken on the Ribadeo I wreck. Questions discussed in this paper include: does every team member need to be a 3D expert? Does a 3D specialist need to be an archaeologist? Is it enough to have a specialist 3D ‘navigator’, someone who can drive the software through the data and act as a guide to a wider team to deliver their own interpretation of the evidence? When conventional outputs are required, including plans, sections, profiles and other nautical-specific views, how can these be efficiently generated from the available photogrammetry and presented to provide comparable information to those who speak and require this type of visual language? This paper does not provide simple or definitive answers to these questions. However, the work undertaken so far on Ribadeo I can offer some contributions to current discussions and consider the challenges within the context of an internationally important shipwreck and work that is necessarily limited by available time and funds.

Photogrammetry as a Digital Tool for Joining Heritage Documentation in Architectural Education and Professional Practice

Abstract: Given the accelerated technological advance in all fields, vast knowledge of digital tools becomes mandatory for future interior designers and architects. Thus, experimenting with as many such methods and technologies must become a priority for the teaching process. Noticing a high demand for digitalization during the COVID-19 pandemic, the Polytechnic University of Timisoara has decided to encourage the implementation of digital teaching throughout disciplines, preparing students for their future careers. Photogrammetry as a study method, among others, has the potential to outrank traditional documentation techniques currently applied in architectural education and practice. The presented research was divided into two main phases: an educational, experimental workshop and a project restoration application. After learning, testing, and refining the close-range photogrammetry workflow, the authors and students took the best practices and applied them to an ongoing facade restoration project in Timisoara, scanning original and restored plaster ornaments and finally 3D printing one of the models. The article aims to show that, unlike traditional teaching methods, using photogrammetry as a documentation process creates a coherent link between theoretical education and restoration practice. Consequently, the exercise brings students closer to the applicable side of their careers through a contemporary digital technique.