Laser Scanning Survey Research Articles

Environmental Impact Assessment of Different Manufacturing Technologies Oriented to Architectonic Recovery and Conservation of Cultural Heritage

Our cultural society has made remarkable advancements in creating digital models that depict the built environment, landscape, and reality. The advent of technologies such as terrestrial laser scanning and drone-based photogrammetry, coupled with sophisticated software capable of processing hundreds of photographs to generate point clouds, has elevated the significance of three-dimensional surveying in documentation and restoration. Point cloud processing and modeling software enable the creation of precise digital replicas of the investigated architecture, which can be scaled down and transformed into physically identical models. Through the export of STL files and the utilization of both subtractive and additive 3D printing technologies, tactile models resembling traditional manually crafted plastics can be obtained. An exemplary study focuses on the Gothic church of Santa Maria Alemanna in Messina, Italy, where laser scanner surveys and 3D prints using various technologies were applied to different parts of the building. The models were produced using a CNC milling machine and a 3D printer for fused deposition modeling. The sustainability of these production technologies was assessed through a Life Cycle Assessment, demonstrating the environmental advantages of additive manufacturing, including the use of materials with high recyclability and lower energy consumption. Additionally, the additive approach helps reduce processing waste.

Trmun (north-eastern Italy): Multi-scale remote and ground-based sensing of a Bronze Age and post-Roman fortification

We have used multi-scale remote sensing to investigate a little known archaeological site in northern Istria (north-eastern Italy). Airborne Laser Scanning (ALS) and archaeological field surveys have allowed us to identify the position and extension of a large Protohistoric hillfort. Its highest and best-preserved sector, corresponding to a modest elevation at the eastern margin of the settlement, has been further investigated through thermal imaging, high-resolution ALS, drone Structure from Motion (SfM) photogrammetry and 3D Ground Penetrating Radar (GPR), leading to a detailed identification of unexpected buried features. An excavation campaign conducted in 2022 has confirmed the remote and ground-based sensing results. This excavation has led to the discovery of a Bronze Age fortification, partially reused and modified with the construction of 2 or 3 square towers during the post-Roman period. Our results demonstrate that the combined analysis of multi-scale remote and ground-based sensing is crucial to planning archaeological exploration in the field. Digital methods provide high-resolution topography and detect buried features that assist in monitoring and managing cultural heritage.

Restoration of the Church of St. Nicholas Fort Ricasoli: The Process of Conserving Our Heritage

Restoration programmes aid in preserving local building heritage for futuregenerations. Documentation of these restoration programmes is a fundamental taskin conserving and reserving significant cultural cultural buildings. Documenting anddeveloping a conservation strategy for a historical structure is quite a complex task andrequires not only planning the interventions required to conserve a building but also forfuture maintenance to enhance the effectiveness of such work. This paper is divided intofive sections. The first section, the introduction, gives a description and overview of thesubject being studied. In the second section, the existing literature study evaluates differentparadigms of protecting existing significant historic buildings. This is followed by anexplanation of the historical context and the history related to the subject studied. Finally,research on the documentation process is also reviewed. The third section describes themethodological approach that aided the analysis of this studys research questions in thefourth section. The fifth section gathers the primary and secondary data analysed and sumsup everything in accordance with the proposed research questions of this study. In order toconduct this research, the Church of St. Nicholas at Fort Ricasoli was used as the main casestudy. A detailed investigation of the church to identify the significance of conserving suchbuildings and an investigation of the existing conditions of the church were conducted. Thisaided in establishing the documentation process prior to the actual interventions on thefabric. In order to carry out such a process, different methods of documentation were used,such as laser scanning surveys, photogrammetry, and documentation of the existing stateof the building to aid in the process of deciding on future interventions. As a result of sucha process, considerations of appropriate uses of such methods and proposals were givenand, additionally, considerations of successful conservation after the actual conservation arehighlighted. The proposal for the conservation of the church of St. Nicholas at Fort Ricasolialso aims to set guidelines for other conservation programmes within the fort, amongstother local restoration projects. Conservation of abandoned structures will enhance thelocal context in various aspects. Finally, conservation programmes will give potentialbenefits to the Maltese islands. Giving back these historically significant monuments to thegeneral public will aid the Maltese islands economy.

COMPARATIVE ANALYSIS OF POINT CLOUDS ACQUIRED FROM A TLS SURVEY AND A 3D VIRTUAL TOUR FOR HBIM DEVELOPMENT

Abstract. This paper presents a comparative analysis of point clouds acquired from a terrestrial laser scanner (TLS) survey and a 3D virtual tour using Matterport technology for heritage building information modeling (HBIM) development. The study uses the Cloister of the Royal College of Corpus Christi Seminary, an important cultural heritage site in Valencia, Spain, as a case study. The point clouds from the TLS survey and Matterport scans were compared both quantitively in CloudCompare software and visually to assess their accuracy and quality. The Matterport point cloud data was found to be slightly lower in quality and accuracy compared to the TLS data, but still sufficient for developing some low-tolerance geometry in the HBIM model. The study shows that Matterport point cloud data has potential to supplement TLS scans, particularly in areas missed during the TLS survey due to range limitations. Matterport technology is accessible, affordable, and easy to use, making it a feasible option for heritage sites with limited resources. Moreover, Matterport technology captures high-quality visual data, including color and texture, providing a detailed representation of the heritage site. Thus, Matterport technology can be a valuable contribution to cultural heritage documentation and preservation, particularly for sites requiring a quick and efficient surveying process. The findings of this research offer insights into the relative advantages and limitations of these two reality capture techniques for cultural heritage documentation and preservation, and could potentially inform decision-making processes for future heritage preservation projects.

Integration, harmonization, and processing of geomatic data for bridge health assessment: the Lastra a Signa case study

A visual inspection, which entails field surveying, such as photodocumentation and footage, is the first step of a multi-level approach to bridge health assessment. Furthermore, the use of surface models, CAD drawings, and orthophotos, guarantees complete and accurate documentation, thus allowing for a better understanding of the environment, the anthropic structures, and their relationships. All the georeferenced surveys’ outputs are especially advisable within a prespective of periodical monitoring, as forseen by national legislation. The work is aimed to study two adjacent bridges over the Arno River in Lastra a Signa, Italy. One of the bridges, Ponte nuovo sull’Arno, is an overpass for motor vehicles. The other one, which is called Passarella sull’Arno, is a pedestrian viaduct. A topographic reference network has been settled using the GNSS survey technique. 3D point clouds of the bridges have been acquired by performing a Laser Scanning survey. A bathymetric survey has been carried out to acquire a 3D point cloud of submerged bridges’ parts and the riverbed. Through a Photogrammetric survey from RPAS, an orthophoto of the area has been built. Finally, evidence of historical submerged bridge structures has been identified thanks to the multi beam survey. The work’s objective is to integrate surveying geomatics techniques to create a reliable survey of the bridges, the surrounding area, and the riverbed, as support to the most common structural health assessment methods.

Out of steady state: Tracking canopy gap dynamics across Brazilian Amazon

AbstractCanopy gaps are evidence of disturbances on forest landscapes. A forest stand is in constant flux, with long stretches of biomass accumulation punctuated by episodic disturbances. We used multitemporal airborne laser scanning data to compare the gap dynamics of four Amazon forest sites. We assessed gap dynamics over 1.9–3.8 years between 2017 and 2020 at sites in the central, central eastern, southeastern, and northeastern regions of the Brazilian Amazon, over areas ranging from 590 to 1205 ha at each site. Gap size ranged from a minimum of 10 m2 to a maximum of about 10,000 m2. We analyzed four stages of gap dynamics: formation, expansion, persistence, and recovery based on two consecutive airborne laser scanning surveys. The gap fraction at our study sites varied between 1.26% and 7.84%. All the sites have similar proportion of gaps among gap size classes. What notably differed among sites was not the gap size‐distribution, but the relative importance of stages of gap dynamics. Expansion and persistence rates ranged from 12 to 118 m2 ha−1. The gap formation rate (formation + expansion) was lower than the recovery rate for three of the four study sites. In contrast, the southeastern site has 1.44 times more area in formation and expansion compared to gap recovery. Over the 2–4 years interval of our study, no site was close to steady state. Multitemporal analyses of large areas over many years are needed to improve our understanding of tropical forest dynamics.

Can the Perception Data of Autonomous Vehicles Be Used to Replace Mobile Mapping Surveys?—A Case Study Surveying Roadside City Trees

The continuous flow of autonomous vehicle-based data could revolutionize current map updating procedures and allow completely new types of mapping applications. Therefore, in this article, we demonstrate the feasibility of using perception data of autonomous vehicles to replace traditionally conducted mobile mapping surveys with a case study focusing on updating a register of roadside city trees. In our experiment, we drove along a 1.3-km-long road in Helsinki to collect laser scanner data using our autonomous car platform ARVO, which is based on a Ford Mondeo hybrid passenger vehicle equipped with a Velodyne VLS-128 Alpha Prime scanner and other high-grade sensors for autonomous perception. For comparison, laser scanner data from the same region were also collected with a specially-planned high-grade mobile mapping laser scanning system. Based on our results, the diameter at breast height, one of the key parameters of city tree registers, could be estimated with a lower root-mean-square error from the perception data of the autonomous car than from the specially-planned mobile laser scanning survey, provided that time-based filtering was included in the post-processing of the autonomous perception data to mitigate distortions in the obtained point cloud. Therefore, appropriately performed post-processing of the autonomous perception data can be regarded as a viable option for keeping maps updated in road environments. However, point cloud-processing algorithms may need to be adapted for the post-processing of autonomous perception data due to the differences in the sensors and their arrangements compared to designated mobile mapping systems. We also emphasize that time-based filtering may be required in the post-processing of autonomous perception data due to point cloud distortions around objects seen at multiple times. This highlights the importance of saving the time stamp for each data point in the autonomous perception data or saving the temporal order of the data points.

Combined use of deformation and structural analysis for the structural damage assessment of heritage buildings: A case study in the Liguria region (Italy)

Cultural heritage buildings as they appear today are the result of continuous transformations occurred over the centuries. For this reason, their structural assessment should integrate structural analysis with a deep knowledge of the building history, actual geometry, damage, past alterations, and actions undergone over time. This paper presents the structural damage assessment of San Carlo Borromeo church, a historic masonry building located in the Liguria region (Italy) in a slow-moving landslide-affected area. To assess the effect of the landslide and identify the causes of the damage and deformations observed in the building, structural analysis was combined with historical research, on-site inspections, laser scanner survey and deformation analysis. A finite element model of the entire church in its geometric undeformed configuration was prepared by removing all the deformations identified through the deformation analysis from the actual deformed geometry obtained from the laser scanner survey. Nonlinear static analyses were then performed by applying at the base of the model a set of displacement fields obtained from the deformation analysis and representing the displacements experienced by the building due to the landslide and further phenomena that were found to have occurred. The damage and deformations predicted numerically were compared with those detected in the church. The good agreement proved that the deformation analysis is an effective tool to support structural analysis and assess the actual deformations and displacements experienced by historic masonry constructions.

H-BIM and Artificial Intelligence: Classification of Architectural Heritage for Semi-Automatic Scan-to-BIM Reconstruction

We propose a semi-automatic Scan-to-BIM reconstruction approach, making the most of Artificial Intelligence (AI) techniques, for the classification of digital architectural heritage data. Nowadays, Heritage- or Historic-Building Information Modeling (H-BIM) reconstruction from laser scanning or photogrammetric surveys is a manual, time-consuming, overly subjective process, but the emergence of AI techniques, applied to the realm of existing architectural heritage, is offering new ways to interpret, process and elaborate raw digital surveying data, as point clouds. The proposed methodological approach for higher-level automation in Scan-to-BIM reconstruction is threaded as follows: (i) semantic segmentation via Random Forest and import of annotated data in 3D modeling environment, broken down class by class; (ii) reconstruction of template geometries of classes of architectural elements; (iii) propagation of template reconstructed geometries to all elements belonging to a typological class. Visual Programming Languages (VPLs) and reference to architectural treatises are leveraged for the Scan-to-BIM reconstruction. The approach is tested on several significant heritage sites in the Tuscan territory, including charterhouses and museums. The results suggest the replicability of the approach to other case studies, built in different periods, with different construction techniques or under different states of conservation.

Исследование точности построения цифровой модели рельефа в зависимости от плотности наземного лазерного сканирования

The authors discuss the course of processing the terrestrial laser scanning survey data (TLS). The aim of the study is to assess the accuracy of creating digital elevation models (DEMs) depending on the scanning step. As initial data, a stitched and oriented cloud of points of the surveyed surface in the territory of the industrial site was taken; it was subsequently used to create digital elevation models using the TIN method. At the next stage of the study, 6 surveys with different scanning steps (from 0,3 m to 5 m) were artificially simulated in the Cyclone software; after that a comparative analysis of the obtained DEMs building accuracy was carried out. The main indicator of model precision is the root-mean-square deviation (RMSD). In the course of the study, the quality of making a digital elevation models was assessed and the dependence of the surface construction error on the increase in the scanning step was determined.

Accurate deformation analysis based on point position uncertainty estimation and adaptive projection point cloud comparison

The accuracy of the scanning scene representation and corresponding points extraction are key factors in deformation analysis based on point cloud. Still, little is known about the influence of terrestrial laser scanner (TLS) survey properties on point cloud. In our study, an accurate deformation analysis method based on point position uncertainty estimation and adaptive projection point cloud comparison is proposed, which consists of two parts: (1) Evaluating the influence of scanning geometry on point cloud quality to gain high accuracy points; (2) an adaptive projection radius and depth point cloud comparison algorithm is constructed for acquiring corresponding points and calculating the deformation. A regular geometry and a landslide point cloud are selected. Results show that the mean error and mean absolute deviation of the distance between corresponding points are –0.3 mm and 16.2 mm, which demonstrates the method can provide an effective solution for the deformation analysis of complex topography.

Il complesso termale Tettuccio a Montecatini Terme. Un patrimonio da svelare

Montecatini Terme, emblematic city for the close combination between thermal baths and urban structure, has been recently enrolled in the list of the Unesco Heritage. It becames particularly urgent to deepen the knowledge, in an appropriate way, of the building ensemble that can be considered the key features in the enrollement, for the purposes of their protection and safeguard. Among these, the Tettuccio bath assumes a particular relevance with regard to the complex architectural articulation, the richness of the decorative characteristics and the variety of the materials used. For this purpose, a laser scanner survey combined with photogrammetry was carried out, thus obtaining a high level of instrumental data, integrated by accurate in-place information. This approach highlighted the materials, traditional and modern, and the decay of the building, founded by the grand duke Pietro Leopoldo and almost completely refashioned about a century ago.

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.

Seismic vulnerability analysis and structural rehabilitation of a historical masonry tower

This paper presents the results of the structural performance assessment of an existing masonry tower and the subsequent repair and strengthening intervention. The study deals with an Italian architectural heritage building in the Cilento National Park (Southern Italy): the bell tower in Torre Orsaia. The tower has been the subject of on-site diagnostic investigations including geometrical surveys, laser scanning surveys, flat jack tests, endoscopic tests, sonic pulse velocity tests, geognostic surveys, and tie-rods tests. The multilevel assessment path proposed by the Italian Guidelines for the assessment and mitigation of the seismic risk of the cultural heritage is followed and the corresponding results are discussed. The global inelastic behavior of the masonry tower is studied through a macro-model approach using the nonlinear static (pushover) analysis. The local collapse mechanisms are studied through a kinematic limit analysis based on rigid block rotation. The repair and strengthening interventions have shown their effectiveness to close the existing cracks, preventing damage to the belfry, and improving the seismic performance of the tower. Both the compatibility, durability, and reversibility of the interventions and their reliability and monitoring are finally highlighted since the bell tower of Torre Orsaia is a historical heritage building.

Landslide Analysis combining Laser Scanning and Photogrammetry

After a sequence of weeks of heavy raining, a catastrophic mass movement occurred in the parish of Palmeira de Faro, Esposende (N Portugal) on November 23, 2022. The collapsed slope presented a maximum height of about 21 m and a length of 45 m. In order to document and analyse this case from the geotechnical perspective, a general survey was devised including the use of aerial photography, laser scanning and conventional topographic survey methods. The results obtained showed that these techniques provide very accurate and abundant information that is essential to support a comprehensive documentation of the features and variables of the slope. The mechanisms involved in this catastrophic collapse are still under investigation, and causes such as the excessive rainfall in the previous months or geologic conditions are still being considered, although currently the existing information seems to indicate for a combination of debris flow / rock slide driven event.

Digitizing an Excavation: A Laser Scanning Database of Maya Architectural Remains

Excavating an ancient Maya city requires a long-term archaeological project that entails adequate documentation procedures for the unearthed remains, frequently of monumental scale and with difficult preservation conditions. A digital laser scanner survey methodology was designed and implemented to document the exposed architecture and to follow-up the archaeological excavation of the Maya site of La Blanca (Peten, Guatemala). All scans collected during the different field seasons were stored and aligned in a common reference system. Thus, an accurate digital three-dimensional database was obtained, including all the architectural remains found, some of which had to be reburied to ensure their preservation. The resulting database is a helpful repository that facilitates to extract all the graphic outputs required for: planning the next excavation campaigns, monitoring the preservation of the buildings, studying the architecture and construction technology in detail, and disseminating the excavation results. This paper describes the methodology and procedures used to build-up this database.

From direct to digital survey. The Abbey of San Giovanni Battista in Lucoli (L’Aquila)

Lucoli is a scattered municipality in the area of L’Aquila, in the Italian region of Abruzzo. In this place between the mountains of the conca Aquilana stands the Abbey of San Giovanni Battista, an important historic and religious site. Despite the damage suffered caused during the 2009 earthquake, the local people still use it and look at it as a symbol of community. With the aim of analyse and so mitigate the seismic vulnerability, the abbey has been the subject of an architectural survey with direct method in a first step, and then of digital laser scanning survey at a later stage, to integrate and verify the first.

Morphology, flow dynamics and evolution of englacial conduits in cold ice

AbstractMeltwater routing through ice masses exerts a fundamental control over glacier dynamics and mass balance, and proglacial hydrology. However, despite recent advances in mapping drainage systems in cold, Arctic glaciers, direct observations of englacial channels and their flow conditions remain sparse. Here, using terrestrial laser scanning (TLS) surveys of the main englacial channel of cold‐based Austre Brøggerbreen (Svalbard), we map and compare an entrance moulin reach (122 m long) and exit portal reach (273 m long). Analysis of channel planforms, longitudinal profiles, cross‐sections and morphological features reveals evidence of spatial variations in water flow conditions and channel incision mechanisms, and the presence of vadose, epiphreatic and phreatic conditions. The entrance reach, located at the base of a perennial moulin, was characterized by vadose, uniform, channel lowering at annual timescales, evidenced by longitudinal grooves, whereas the exit portal reach showed both epiphreatic and vadose conditions, along with upstream knickpoint migration at intra‐annual timescales. Fine‐scale features, including grooves and scallops, were readily quantified from the TLS point cloud, highlighting the capacity of the technique to inform palaeoflow conditions, and reveal how pulses of meltwater from rainfall events may adjust englacial conduit behaviour. With forecasts of increasing Arctic precipitation in the coming decades, and a progressively greater proportion of glaciers comprising cold ice, augmenting the current knowledge of englacial channel morphology is essential to constrain future glacier hydrological system change.

La digitalizzazione del patrimonio come strumento per la conoscenza, un’esperienza sull’architettura ferroviaria siciliana

The process of digitisation of the artistic and cultural heritage has enriched the possibilitiesof representation and communication of architecture, increasing the modes of reproduction,fruition as well as the possibilities of protection and preservation. The study of this researchdraws attention on the continuous progress of technology in the cultural fi eld and highlightsthe important collaboration that exists between digital and analog representation, identifying,with this synergy, a virtuous path that allows, through the use of different methodologies, tobe able to know and analyze the historical phases of a building. In particular, the attentionwas directed to the Caltanissetta Centrale station, a signifi cant junction of the Sicilian railwaynetwork both for the connection of the island and for the sulfur trade. With its late modernism,the station under study is part of the story of Art Nouveau stations in Sicily, and it becomes awitness to economic and social changes in the region, thus making itself an asset to be protectedand disseminated. Through the study of iconographic documents, historical photos, and graphicanalysis it was possible to retrace, through a backward process from the laser scanning survey tothe study of photographic restitution, the main historical phases that characterised the evolutionand extension of the factory. Through such 3D graphic representations, it was also possible toreproduce the characteristics of the building and highlight the changes that occurred over timeand the evident divergences that existed between the building and the original design idea.

Study of Point Cloud Integration between UAV-based Dataset and Aerial LiDAR Survey

The migration of Photogrammetry from the analog medium to the digital medium changed how photogrammetric surveys were carried out and how data are processed, allowing the automation of several steps used in the photogrammetric design workflow. There is extensive research in cartographic and geodetic sciences, involving the acquisition of data through photogrammetry, and through techniques such as Structure from Motion (SfM) and Laser Scanner survey. Such research and work involve the use of point clouds from Unmanned Aerial Vehicle (UAV) photogrammetric surveys and Terrestrial Laser Scanner (TLS) surveys, as well as the fusion of these point clouds. This work aims to study the integration of an aerial LiDAR point cloud with a Photogrammetric Point Cloud (PPC) from the UAV survey to minimize occlusion failures and building edges, densify the point cloud, and reduce spurious points. Statistical analyses were performed for the refinement, adjustment, and integration between the point clouds. The results showed that the correction map generated for integrating the clouds reached the objective proposed in this work. The integration of clouds increased from 7 pts/m² of the cloud coming from LiDAR to 140 pts/m² in the final.