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Surveying and modelling the Main Spire of milan Cathedral using multiple data sources
Abstract
This paper presents a possible way of surveying and modelling very complex architecture, integrating different instrumentation and modelling methods. In particular, it aims to draw attention to a possible measurement and data processing procedure allowing the rapid collection and post-processing of data in order to extract classical architectural products such as sections and profiles, and to build complete, accurate 3D models. The need is to structure a multiple data source procedure within a five-year project (still in progress) to survey and model the main spire of Milan Cathedral three-dimensionally. The spire is a very complex object and, for this reason, provides a really useful, challenging field test for new 3D survey technologies and, in particular, for integrating a variety of modelling methodologies. The paper describes survey workflow and processing steps, focusing on problems and justifying key choices.
... Multi-platform data fusion can make up for the problems of incomplete data and excessive data errors that exist in a single platform. For example, Fassi et al. (2011) [82] proposed that in order to understand the global structure of complex artifacts (e.g., Milan Cathedral's main spire, Italy), together with its reconstruction accuracy, connections, and topological and geometrical logic, different instruments and modeling methods must be used and integrated. Achille et al. (2015) [83] constructed a 3D model of interior and exterior buildings with complex structures by integrating UAV photogrammetry and TLS data. ...
... Multi-platform data fusion can make up for the problems of incomplete data and excessive data errors that exist in a single platform. For example, Fassi et al. (2011) [82] proposed that in order to understand the global structure of complex artifacts (e.g., Milan Cathedral's main spire, Italy), together with its reconstruction accuracy, connections, and topological and geometrical logic, different instruments and modeling methods must be used and integrated. Achille et al. (2015) [83] constructed a 3D model of interior and exterior buildings with complex structures by integrating UAV photogrammetry and TLS data. ...
... Fassi et al. [82] UAV Photogrammetry (Canon ...
In the cultural heritage field, point clouds, as important raw data of geomatics, are not only three-dimensional (3D) spatial presentations of 3D objects but they also have the potential to gradually advance towards an intelligent data structure with scene understanding, autonomous cognition, and a decision-making ability. The approach of point cloud semantic segmentation as a preliminary stage can help to realize this advancement. With the demand for semantic comprehensibility of point cloud data and the widespread application of machine learning and deep learning approaches in point cloud semantic segmentation, there is a need for a comprehensive literature review covering the topics from the point cloud data acquisition to semantic segmentation algorithms with application strategies in cultural heritage. This paper first reviews the current trends of acquiring point cloud data of cultural heritage from a single platform with multiple sensors and multi-platform collaborative data fusion. Then, the point cloud semantic segmentation algorithms are discussed with their advantages, disadvantages, and specific applications in the cultural heritage field. These algorithms include region growing, model fitting, unsupervised clustering, supervised machine learning, and deep learning. In addition, we summarized the public benchmark point cloud datasets related to cultural heritage. Finally, the problems and constructive development trends of 3D point cloud semantic segmentation in the cultural heritage field are presented.
... It can be accomplished using several different techniques, including photogrammetry (Shao et al., 2015), depth camera (Henry et al., 2012) and laser scanning (Lee et al., 2013). While applications of virtual environments have been reported for several disciplines, for example, cultural heritage (Ogleby, 1999;Portales et al., 2009;Anderson et al., 2010), architecture and construction (Herwig and Paar, 2002;Fassi et al., 2011), the 3D models used have typically been produced by combining manual modelling techniques with 3D data (Fassi et al., 2011) or 3D reconstruction has been applied for producing partial models of larger targets (Portales et al.,2009;Virtanen et al., 2015). Specifically, we propose an application of Matterport (Schults et al. 2023) and Unity (Pernas-Álvarez and Crespo-Pereira, 2024) softwares to define dynamic representations of a portion of the online museum of our university. ...
... It can be accomplished using several different techniques, including photogrammetry (Shao et al., 2015), depth camera (Henry et al., 2012) and laser scanning (Lee et al., 2013). While applications of virtual environments have been reported for several disciplines, for example, cultural heritage (Ogleby, 1999;Portales et al., 2009;Anderson et al., 2010), architecture and construction (Herwig and Paar, 2002;Fassi et al., 2011), the 3D models used have typically been produced by combining manual modelling techniques with 3D data (Fassi et al., 2011) or 3D reconstruction has been applied for producing partial models of larger targets (Portales et al.,2009;Virtanen et al., 2015). Specifically, we propose an application of Matterport (Schults et al. 2023) and Unity (Pernas-Álvarez and Crespo-Pereira, 2024) softwares to define dynamic representations of a portion of the online museum of our university. ...
In recent years the digital visualisation techniques, including 3D digital models of indoor spaces, saw an exponential increase in their applications, both in the fields of Architecture, Engineering and Construction (AEC) and of Cultural Heritage (CH). This growth is mainly due to the increasing affordability of tools for the acquisition and elaboration of three-dimensional digital survey/data management and to their increasing ‘user friendliness’.The research proposes a further step on research started some years ago by our group about the exploration of indoor mapping for the creation of the 3D virtual museum of our Institution, starting with the realisation of a virtual model of the university’s spaces (departments and halls). At first, the virtual museum will host the Curioni Digital Collection, which consist of circa 140 wooden models of building details, bridges, tunnels, and vaults designed by prof. G. Curioni during the second half of the XIX century as teaching aids for the Construction and Structural Design classes. A comparison between two main tools to support management and diffusion of geometrical, alphanumerical, and topological data will be given (Matterport and Unity). The parallel approach considering two tools is to provide a digital twin of a real collection placed in a real space, and, on the other hand, to use a real historical university space, virtualized, to host a virtual collection.
... Spesso i rilievi fotogrammetrici sono una soluzione ottimale per eseguire il rilievo in modo economico e in tempi brevi con l'utilizzo di fotocamere digitali non metriche, accuratamente calibrate con algoritmi e procedure appropriate e specifi che. Sensori attivi come la scansione laser vengono utilizzati per indagare un oggetto o un sito, fornendo nuvole di punti 3D che possono essere unite con passaggi ben fi ssati (Fassi et al., 2011;Gilardoni, 2007;Guidi et al., 2009;Remondino, Campana, 2014). La fotogrammetria può essere defi nita come " the process of deriving (usually) metric information about an object through measurement made on photographs of the object" (Mikhail et al., 2001 p. 1). ...
... Often, photogrammetric surveys are an optimal solution to perform the survey in an economical way and in a short time with the use of digital non-metric cameras, carefully calibrated with appropriate and specifi c algorithms and procedures. Active sensors such as laser scanning are used to investigate an object or site, providing 3D point clouds that can be merged (Fassi et al., 2011;Gilardoni, 2007;Guidi et al., 2009;Remondino, Campana, 2014). Photogrammetry can be defi ned as "the process of deriving (usually) metric information about an object through measurement made on photographs of the object." ...
3D printing artefacts and monuments allows blind and visually impaired people to discover,understand and enjoy the beauty of Cultural Heritage. The reproduction of the artefactsusually starts with the 3D survey with reality-based techniques in order to obtain their metric,accurate digital copy. With a proper post-processing, the digital model is then set up ready forthe printing. The result is a physical model that can be touched and inspected, making the artvisible to everyone.This paper presents the pipeline followed for the 3D reproduction of the famous Michelangelo’sTomb of Giulio II, visible in San Pietro in Vincoli church in Rome. The photogrammetricsurvey is descripted and evaluated, and all the process followed to postprocess the 3D modelin order to make it countable for the 3D printing. A particular attention was given to theproblems occurred during the survey (lack of space, lights) and then the postprocessing relatedto the creation of different printed physical models. The fi nal models have been printed inaccomplish with the requests of the costumer, in order to make them suitable for blind people.
... They are used in the field of architectural heritage, where large buildings are documented, along with small scale details marking unique features, historic techniques and ongoing decay. Fassi et al. 14 show CRP and TLS are useful at scales similar to this study. The use of CRP in combination with other techniques has come a long way: Yilmaz et al. 15 track fire damage of a historic building by combining photogrammetry and basic measurements, while recent studies have focused on TLS integration 16 , combined drone-and terrestrial CRP 17 and specific downstream methods such as for construction sites and (H)BIM 16,18 . ...
... While in simple structures a small number of accurate data points can be collected (e.g. using tacheometry) to represent edges and corners onto which shape primaries are mapped, in complex structures (e.g. an irregular curve in a branch) simple curves and surfaces cannot be easily interpolated and edges and corners are not clear. This challenge is present, for example, in heritage documentation 14,25 . The shape primaries useful in mechanical and physiological tree models are typically 1D elements connected at branching and joining points. ...
Living architecture, changing in structure with annual growth, requires precise, regular characterisation. However, its geometric irregularity and topological complexity make documentation using traditional methods difficult and presents challenges in creating useful models for mechanical and physiological analyses. Two kinds of living architecture are examined: historic living root bridges grown in Meghalaya, India, and contemporary ‘Baubotanik’ structures designed and grown in Germany. These structures exhibit common features, in particular network-like structures of varying complexity that result from inosculations between shoots or roots. As an answer to this modelling challenge, we present the first extensive documentation of living architecture using photogrammetry and a subsequent skeleton extraction workflow that solves two problems related to the anastomoses and varying nearby elements specific to living architecture. Photogrammetry was used as a low cost method, supplying detailed point clouds of the structures’ visible surfaces. A workflow based on voxel-thinning (using deletion templates and adjusted p-simplicity criteria) provides efficient, accurate skeletons. A volume reconstruction method is derived from the thinning process. The workflow is assessed on seven characteristics beneficial in representing living architecture in comparison with alternative skeleton extraction methods. The resulting models are ready for use in analytical tools, necessary for functional, responsible design.
... Lo svantaggio è la complessità della procedura per integrare i dati dei sensori attivi e passivi e la più complessa definizione di un flusso di lavoro efficiente. Il tema è sempre stato di interesse nel panorama di ricerca internazionale [Beraldin 2004;Fassi 2007;Fassi 2011] e sono state proposte diverse soluzioni [Adamopoulos 2017;Galli 2019;Luhmann 2019]. La ricerca presentata mira a definire una soluzione innovativa e una pipeline operativa per combinare nuvole di punti da più sensori (attivi e passivi). ...
... The disadvantage is the complexity of the procedure to integrate data from the active and passive sensors and the more complex definition of an efficient workflow. The well-known topic has always been of interest in the international research panorama [Beraldin 2004;Fassi 2007;Fassi 2011] and different solutions have been provided [Adamopoulos 2017;Galli 2019;Luhmann 2019]. This research aims to define an innovative solution and an operative pipeline to combine point clouds from several sensors (active and passive). ...
Digital technologies provided an opportunity for innovation and development in the graphic representation field during the pandemic when scientific communication was forced into digital communication channels.
The digital survey with the image-based and range-based techniques integration allows optimizing 3D measurements and the related technical representations. This study presents the analysis of an innovative pipeline to integrate the Terrestrial Laser Scanner (TLS) dataset directly into the photogrammetric pipeline within a single software environment. The main objective was to test different procedures for the alignment and integration of point clouds from active (TLS) and passive (close-range photogrammetry) sensors and provide a first metric evaluation.
In particular, three methods were analyzed: scale and roto-translation with Ground Control Points through the photogrammetric self-calibration bundle adjustment; integration of the spherical panoramas by the single laser stations into the photogrammetric workflow; Python script to align the photogrammetric dense cloud in the TLS reference system through an Iterative Closest Point (ICP) procedure. The study presents the first results applied to a small architectural scale case study: the Mulino del Cantone, a watermill along the Lambro river in the Park of Monza (MB). The mixed approach opens new opportunities to achieve an efficient 3D survey and a complete graphic representation.
... The appearance of massive data capture techniques has raised countless applications in very diverse disciplines, such as geomorphology [1], volcanology [2], prototyping [3], construction materials [4], and also cultural heritage [5], both architectural and archaeological. In these areas, we find numerous works based on surveys carried out mainly with a terrestrial laser scanner (TLS) [6,7], digital photogrammetry [8,9], or a combination of both [10,11]. The reliability and accuracy of these systems has been extensively tested and verified [12][13][14]. ...
... Geosciences 2020, 10 Publisher's Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. ...
The use of massive data capture techniques in architectural heritage has enhanced the development of new methodologies that have an important impact on their conservation and understanding. The research proposes the study of formal anomalies in the cloister of the Cathedral of Tarragona (c. 12th century). It is a relevant Gothic construction in Catalonia, with the special singularity that part of its structure is raised over an important pre-existing Roman wall. The investigation is based on a point cloud obtained with a terrestrial laser scanner (TLS) and the systematization of the 3D analysis methodology of the point cloud through different reference shapes. In general terms, the construction is in good condition, so the discrepancies between real construction and the shapes of reference are small, with some exceptions. Nevertheless, the different approximations used allowed us to identify some relevant features, such as the variability of the form of rib vaults, and the influence of the criteria used in the definition and location of reference forms.
... With the increasing demand for capturing 3D spatial data, there is a growing need for cost-effective and efficient methods for data acquisition. Traditional methods, such as photogrammetry and static Terrestrial Laser Scanning (TLS), provided highly accurate 3D spatial data for many years in heritage and architectural scenarios (El-Hakim et al., 2007;El-Hakim et al., 2008;Fassi et al., 2011;Remondino, 2011). Recently, Mobile Mapping Systems (MMS), either with LiDAR sensors, cameras (visual) or an integration of both sensors, offer a promising alternative combining affordability, flexibility and reduced acquisition times, making them versatile and suitable for a wide range of applications, even in complex scenarios (Nocerino et al., 2017;Di Stefano et al., 2021;Elhashash et al., 2022). ...
Traditional 3D surveying methods often fall short in complex spaces due to lack of mobility, time constraints and high risk. For this reason there is an actual demand for 3D data acquisition tools and methods, particularly suitable for complex and narrow environments, due to their capacity for efficiently capturing detailed and accurate spatial information, maybe also automatically. This study presents a novel approach for fusing 3D spatial data collected by two separate and independent mobile mapping systems: (1) ATOM-ANT3D and (2) MandEye. We propose an innovative fusion technique that combines visual and LiDAR data from asynchronous acquisitions, reducing the need for strict temporal and spatial synchronizations between the two systems. We compare the outputs of both systems before and after fusion, studying the individual limitations and highlighting the complementary benefits achieved by the proposed fusion framework. Results demonstrate improved accuracy of global alignment and spatial completeness of the final point clouds, proving the efficiency and flexibility of the proposed approach.
... Complex and irregular shapes are common in this type of constructions, which are frequently characterized by its large scale, making certain elements inaccessible. Numerous investigations have tested the technique's reliability to survey a building's geometry [1][2][3][4]. ...
... However, this paper does not explicitly focus on using different digital tools and their integrated use for surveying complex geometry. The reader is referred to several technical papers describing real case studies [7][8][9][10][11][12][13][14][15][16][17][18]. ...
Digital recording of historic buildings and sites in mountainous areas could be challenging. The paper considers and discusses the case of historical defensive structures in the Italian Alps, designed and built to be not accessible. Drone images and photogrammetric techniques for 3D modeling play a fundamental role in the digital documentation of fortified constructions with non-contact techniques. This manuscript describes the use of drones for reconstructing the external surfaces of some fortified structures using traditional photogrammetric/SfM solutions and novel methods based on NeRFs. The case of direct orientation based on PPK and traditional GCPs placed on the ground is also discussed, considering the difficulties in placing and measuring control points in such environments.
... Grussenmeyer et al. (2012) propose a CH documentation approach that involves using the two techniques and validating the goodness of fusion based on visual crosssection checks and quantitative checks using topographic * Corresponding author measurements. Fassi et al. (2011) present an approach aimed at three-dimensional modeling that integrates TLS survey with high-resolution close-range photogrammetry of decorated elements. Achille et al. (2015) present an approach that combines an interior TLS survey with an exterior Unmanned Aerial Vehicle (UAV) photogrammetric survey of a bell tower to obtain a complete 3D model; Achille et al. (2020) and Perfetti & Fassi (2022a) demonstrate the effectiveness of integrating indoor TLS, outdoor photogrammetry, and multi-camera surveys for narrow spaces. ...
Point clouds are nowadays a standard format of three-dimensional data. Various survey techniques are available, differing in characteristics, mode of use, and target applications, nevertheless producing point clouds that are similar, comparable, and combinable. According to recent literature, combining data from multiple sensors is an established practice for large surveying projects, particularly in Cultural Heritage, where the geometric complexity of buildings encourages the employment of many sensors. This paper presents a multi-sensor approach to surveying complex architectural spaces. The case study is the Cathedral of Aosta (AO) in Italy, which is interested in a conservation project that requires investigating the two bell towers of the cathedral. The survey aimed to produce a point cloud of 5 mm resolution and 1–2 cm accuracy compatible with the 1:50 scale of representation. The following survey techniques were employed: (i) laser scanning, (ii) terrestrial photogrammetry, (iii) UAV photogrammetry, and (iv) multi-camera fisheye photogrammetry. The distinctive feature of our approach lies in the multi-camera survey, conducted using a prototype composed of five fisheye cameras. The paper describes the data acquisition phase conducted with the different techniques, the mutual verification of the data performed by cross-sections check, the segmentation, and the final assembly of the various portions until a complete point cloud with homogeneous characteristics is obtained. All the data were then collected in a web platform (FlyVast) enriched with data and info made available to the professional to plan future interventions.
... The other two typologies, on the other hand, seemed to have been applied in more specific contexts so far, with a few areas of science monopolising their implementation (Figure 4a,c). In fact, the disciplines showing a predilection for ground-based approaches are cultural heritage/archaeology (164), geosciences (87), and architecture/civil engineering (78) (Figure 4a), which benefited from the opportunity to monitor scenarios from a 3D perspective, a useful approach in terms of structure integrity assessments [65][66][67]. Concerning cultural heritage, photogrammetry also allowed for the possibility for the development of virtual repositories, an emerging tool in constant evolution thanks to its huge potential in terms of science transfer and education [68,69]. In the matter of underwater applications, Biology/Ecology (46) and Cultural Heritage/Archaeology (28) were the disciplines mostly exploiting the technique (Figure 4c). ...
The series of technological advances that occurred over the past two decades allowed photogrammetry-based approaches to achieve their actual potential, giving birth to one of the most popular and applied procedures: structure from motion (SfM). The technique expanded rapidly to different environments, from the early ground-based and aerial applications in terrestrial scenarios, to underground and underwater surveys. Nevertheless, the transfer through different media required a period of adaptation that could take anything from years to decades. Only recently, thanks to the emergence of low-cost versatile imaging systems, have airborne and underwater photogrammetry became approachable to a wide range of research budgets, resulting in a popular cost-effective solution for many disciplines. Although numerous review efforts have already been made to resume the current knowledge on photogrammetry, this review summarizes the evolution of the technique in both terrestrial and underwater environments, paying special attention to the transfer of methods and techniques between the two environments. The acquired information helped to identify trends during its development and to highlight the urgency to widen the range of its applications in aquatic habitats in order to fill the current gap of knowledge on their structure and species distribution, delaying the design of proper conservation strategies.
... This constraint in close-range photogrammetry means that data acquisition is not practical in a complex and heterogeneous forest situation. Despite this fact, close-range photogrammetry has the potential to generate more detail than laser scans, as has been showcased in other applications (Fassi et al., 2011;Menna et al., 2018). ...
This paper is an attempt to respond to the growing need and demand of 3D data in forestry, especially for 3D mapping. The use of terrestrial laser scanners (TLS) dominates contemporary literature for under-storey vegetation mapping as this technique provides precise and easy-to-use solutions for users. However, TLS requires substantial investments in terms of device acquisition and user training. The search for and development of low-cost alternatives is therefore an interesting field of inquiry. Here, we use low-cost 360° cameras combined with spherical photogrammetric principles for under-storey vegetation mapping. While we fully assume that this low-cost approach will not generate results on par with either TLS or classical close-range photogrammetry, its main aim is to investigate whether this alternative is sufficient to meet the requirements of forest mapping. In this regard, geometric analyses were conducted using both TLS and close-range photogrammetry as comparison points. The diameter at breast height (DBH), a parameter commonly used in forestry, was then computed from the 360° point cloud using three different methods to determine if a similar order of precision to the two reference datasets can be obtained. The results show that 360° cameras were able to generate point clouds with a similar geometric quality as the references despite their low density, albeit with a significantly higher amount of noise. The effect of the noise is also evident in the DBH computation, where it yielded an average error of 3.5 cm compared to both the TLS and close-range photogrammetry.
... In ecology and biology, soil geometry and conditions are investigated to infer the relationship with vegetation, animal life [19] and climate change [20]. In the architectural and cultural heritage domains, photogrammetry is employed to document the state of conservation of buildings and support maintenance and restoration interventions [21][22][23][24]. ...
Digital photogrammetry is a widespread surveying technique in different fields of application due to its flexibility, versatility and cost-effectiveness. Despite its increasing automation and simplicity, a proper image block design is crucial to ensure high standards of performance and accuracy. Studies on camera network design have been largely dealt with in the scientific literature with reference to image orientation process, while they are still poor on dense matching. This paper investigates the influence of different block geometry configurations on multi-image dense matching. Starting from the same orientation solution, dense matching was performed considering different combinations of number of images and base length distance between the first and the last image within a strip. The raster Digital Elevation Models (DEM) resulting from each sequence of images were compared with a reference DEM to assess accuracy and completeness. The tests were conducted using different cameras and at various test sites to assess different survey conditions and generalize the findings. The presented results provide some operational guidance on block geometry optimization to maximize the accuracy and completeness.
... Success in the registration process of separate scans may be influenced by the dimension and shape of canopy elements (e.g., understory, stems, branches) and the way they are displayed in the measured 3D space, creating uncertainty in the registration process. To minimize the uncertainty and for better orientation and registration of scans, it is necessary to include a number of survey control points within the forest scene (Fassi et al., 2011). Hence, reference spheres with known dimensions and reflectivity were placed in each forest stand within the scanner field of view and range, in such a way that they can be visible from all TLS positions and recognizable as specific objects within the point cloud. ...
... Since always professionals in building construction or conservation used to only work on "a two-dimensional world" and only used 3D models to convey particular concepts. Only recently have they begun to feel the need to use the threedimensional model more proficiently as a tool for collecting and sharing all data related to the building's life cycle, from design to maintenance (Fassi et al., 2011). As a result, the 3D virtual representation is now known as a "digital twin", emphasizing the fact that it is used to connect data, information that may define behaviour and even non-visible aspects of the thing. ...
Mixed reality provides on-the-spot and real-time data access capabilities by making virtual models and information more intuitive and accessible. Furthermore, allowing the operator to perceive 3D as holograms would allow for a more natural and straightforward manipulation of the perceived 3D content by permitting the augmentation of real objects with various levels of data. This can be accomplished by appropriately registering and superimposing the presented 3D models with the surrounding environment. This work aims to provide a quantitative evaluation of HoloLens 2 capabilities in registering virtual content inside monumental spaces. Two different methodologies are evaluated: Vuforia image targets and Microsoft World Locking Tools (WLTs). Tests have been performed inside Milan Cathedral's monumental spaces. Here, ambience dimensions, single architectural element repetition and non-uniform lighting conditions push out-of-the-box methods to their limits. Results show that WLTs with their space pins API can correctly reference virtual content keeping deviations in the order of 15 cm coping with the scale error produced from sensors’ drifts.
... They can work separately or by combining the two techniques; they can use data from land-based or UAV-mounted cameras (Vacca et al. 2018). The accuracy of terrestrial laser scanner (TLS) systems has been extensively tested and verified (Fassi, Fregonese 2011), (Grussenmeyer et al. 2008) and , while the image-based techniques and their integration with TLS are still the object of study (Pepe et al., 2016). The TLS technique has been used in the study of deformations of ancient structures, of which there are several examples (Bonali et al., 2013), (Pesci et al., 2012) and (De Catalunya et al., 2017). ...
The study presented aims a practical contribution to the use of the Terrestrial Laser Scanner and the Close Range Photogrammetry geomatic techniques and to their integration for the knowledge and development of the historical-architectural heritage, both in the step of planning a restorative conservation project, and in the subsequent step of the restoration works. In particular, these techniques and their integration were applied at the process of study, planning and execution of the restoration of the San Giovanni Battista church in Fonni (Sardinia, Italy), founded in the 16th century. The building, due to structural problems and humidity infiltrations, was subject to a serious intervention for consolidation and conservative restoration.In the first phase of the work, preliminary to the design, a TLS survey was made that allowed to obtain an accurate 3D model of the church. In a second phase, during the restoration work, CRP surveys were carried out and the accuracy of this technique was verified through a comparison with TLS surveys. The integration of the two techniques to improve the texture of point clouds detected with TLS was also tested.
... Several papers and textbooks describe both theoretical concepts and practical issues in digital documentation projects of three-dimensional objects carried out using images [2] and laser scans [3]. The reader is referred to [4][5][6][7][8] for some examples related to digital workflows using a combination of instruments and measuring techniques. This paper aims to show a relatively fast alternative solution that can be used with 360 • low-cost cameras available on the commercial market. ...
This paper describes a method for metric recording based on spherical images, which are rectified to document planar surfaces. The proposed method is a multistep workflow in which multiple rectilinear images are (i) extracted from a single spherical projection and (ii) used to recover metric properties. The workflow is suitable for documenting buildings with small and narrow rooms, i.e., documentation projects where the acquisition of 360 images is faster than the traditional acquisition of several photographs. Two different rectification procedures were integrated into the current implementation: (i) an analytical method based on control points and (ii) a geometric procedure based on two sets of parallel lines. Constraints based on line parallelism can be coupled with the focal length of the rectified image to estimate the rectifying transformation. The calculation of the focal length does not require specific calibrations projects. It can be derived from the spherical image used during the documentation project, obtaining a rectified image with just an overall scale ambiguity. Examples and accuracy evaluation are illustrated and discussed to show the pros and cons of the proposed method.
... The construction of the Ming and the Qing Dynasties' official-style architecture followed certain rules which resulted in the distribution of roof components of buildings in the Ming and Qing Dynasties also obeying some arrangement laws. Hence, in addition to the regular geometric features, which were widely used in other works [17,19,31], the features that came from the construction regulation are also designed in this section. ...
Point cloud semantic segmentation has played an important role in the scan-to-BIM process of the Ming and Qing Dynasties’ official-style architecture roof. To overcome the complexity of roof components’ shape and the scale differences between different roof component types, a point cloud semantic segmentation method for the MQDOAs roof considering the construction regulations is proposed in this paper. This method is composed of two stages. In the first stage, the features from the construction rules of MQDOAs, including the normalized symmetrical distance (NSD), relative height (RH) and local height difference (LHD), are extracted alongside the regular geometric features. To lower the influence of scale differences, a multi-scale feature connection strategy is also applied to construct the feature classification vector. In the second stage, RF method is applied to classify the point cloud. To verify the efficiency of the proposed method, we took the Hall of Complete Harmony as the study case. The experiments showed that our method achieved segmentation result in overall classification accuracy and reached 96.8%.
... These raises the possibility of developing new assessment methodologies based on the 3D documentation [1] [2]. Numerous investigations have tested the techniques' reliability [3], [4] and proved their effectiveness and compatibility to obtain high precision topographical documentation in architectural heritage [5], [6]. ...
Current massive data capture techniques (MDCT), such as terrestrial laser scanning and digital photogrammetry, have become widespread during the last decade, and raises the possibility of developing new assessment methodologies based on the 3D documentation. The paper exposes de results of using simple, non-invasive procedures for the assessment of the shape of a masonry building from a point clouds registered with a terrestrial laser scanner. The case study selected is the church of Sant Miquel of Batea (eighteenth century), located in the province of Tarragona (Spain). The methodology used combines 2D and 3D processes for assessment of the geometry. The results of the investigation have confirmed the good condition of the building. It presents dimensional variations, most of which can be related to the construction process, while some displacements identified provide information about the accommodation process of the masonry structure.
... The authors present the production of accurate and high-resolution 3D models of a cave with engravings dating back to the Upper Palaeolithic era in Spain. A further multiple data source documentation method was implemented by Fassi et al., (2011) to survey the main spire of Milan Cathedral. The authors describe the survey workflow and processing steps, focusing on problems and key choices. ...
In 1985, the World Heritage Committee inscribed the site “Painted Churches in the Troodos Region” of the Republic of Cyprus on the UNESCO World Heritage List. The latter included nine Byzantine and Post Byzantine Churches to which a tenth church was added in 2001. In the framework of the IH-AT project, all the churches and the premises in their proximities were analysed using a wide array of non-destructive digital methodologies coupled with more traditional art-historical studies. Image- and Range-based techniques were used to document all the morphological features of the buildings with the final goal of understanding their humble architecture. Additionally, a Ground Penetrating Radar (GPR) was performed to investigate the presence of buried structures that, according to historical sources, were once surrounding the religious sites.For the exploitation and visualization of the extensive database by the scientific community and the public at large, a web portal comprised of reliable and efficient technology-ready tools have been developed.The proposed methodology was implemented to provide new insights on the churches’ architectural features; confirm the presence or absence of buried remains of archaeological interest; and help heritage professionals, with lack or minimal programming skills, to customize online visualizations of 3D interactive models.
... These raises the possibility of developing new assessment methodologies based on the 3D documentation [1] [2]. Numerous investigations have tested the techniques' reliability [3], [4] and proved their effectiveness and compatibility to obtain high precision topographical documentation in architectural heritage [5], [6]. ...
... While the modelling process is generally easy and straightforward with simple objects or indoor scenarios, it becomes nearly impossible, time-consuming and uneconomic with CH scenarios. In fact, in the CH field, even repetitive objects are different from others when scale and metric accuracy must be retained (Fassi et al., 2011). Furthermore, the modelling phase introduces an unsupervised degree of subjectivity and a reduction in geometric detail that can lower the metric quality intrinsic to the surveyed point cloud. ...
In recent years, Artificial Intelligence (AI) methods for 3D point cloud classification has assumed an essential role in the heritage field. The association of semantic information to 3D representations became a valuable instrument for measurement, analysis, education or maintenance, in particular in the Cultural Heritage (CH) sector. Moreover, the recent availability and reliability of head-mounted displays and glasses are allowing extraordinary immersive virtual experiences. This paper presents an end-to-end framework to handle large and complex 3D point clouds, from acquisition to semantic segmentation and final access in a Mixed Reality (MR) environment. Three completely different heritage scenarios are considered: the Temple of Neptune in Paestum, the Milan Cathedral and a large portion of Bologna’s porticoes. Mixed Reality experiences are described and shown based on the Microsoft HoloLens 2 device. A video of the results is available at https://youtu.be/Kd_3s0tIX04.
... In order to ensure data registration, artificial targets were used in the field. The inclusion of these targets, which are considered as control points within the studied area, minimizes uncertainty by optimizing the orientation in the recording of scans (Fassi et al., 2011). These targets were made up of circular boards (spheres) and checkerboards, which were distributed in the field around the scanning platform in each one of the scans. ...
The adoption of 3D survey techniques is essential to promote efficient and timely information acquisition on constructed buildings. This article addresses terrestrial LiDAR (TLS) and close-range photogrammetric data fusion for the 3D modeling of a building in Level of Detail (LoD) 3. The selected building presents challenging elements for modeling, such as extended curved slabs, external glass walls, recessed facades and diverse roof pitches. It is located on the campus of the Federal University of Paraná (UFPR) in Curitiba, Brazil. The accuracy of the data integration was obtained through the analysis of deviations between the clouds of primary points. The accuracy of the point cloud model was verified by comparing its dimensions with the real dimensions of the building, obtained by means of a handheld laser distance meter (EDM). The results demonstrate that there was a correspondence between the EDM measures and the model, with a satisfactory statistical agreement between the estimated and reference values and a general maximum absolute error of 4.5 cm. The article focuses on the accuracy of point cloud models for the cadastral updating of buildings, providing information for decision making in projects documentation and interventions.
... The aim of this work is to conduct a preliminary test on the possibility of using the digital tools belonging to the manufacturing industry field for the digitisation of Cultural Heritage and as a support to the maintenance practices, taking a further step in the informative modelling process for Milan Cathedral, started in 2011 with the realisation of the Main Spire model (Fassi, Achille, & Fregonese, 2011). ...
Cultural Heritage (CH) 3D digitisation is getting increasing attention and importance. Advanced survey techniques provide as output a 3D point cloud, wholly and accurately describing even the most complex architectural geometry with a priori established accuracy. These 3D point models are generally used as the base for the realisation of 2D technical drawings and 3D advanced representations. During the last 12 years, the 3DSurveyGroup (3DSG, Politecnico di Milano) conduced an omni-comprehensive, multi-technique survey, obtaining the full point cloud of Milan Cathedral, from which were produced the 2D technical drawings and the 3D model of the Main Spire used by the Veneranda Fabbrica del Duomo di Milano (VF) to plan its periodic maintenance and inspection activities on the Cathedral. Using the survey product directly to plan VF activities would help to skip a long-lasting, uneconomical and manual process of 2D and 3D technical elaboration extraction. In order to do so, the unstructured point cloud data must be enriched with semantics, providing a hierarchical structure that can communicate with a powerful, flexible information system able to effectively manage both point clouds and 3D geometries as hybrid models. For this purpose, the point cloud was segmented using a machine-learning algorithm with multi-level multi-resolution (MLMR) approach in order to obtain a manageable, reliable and repeatable dataset. This reverse engineering process allowed to identify directly on the point cloud the main architectonic elements that are then re-organised in a logical structure inserted inside the informative system built inside the 3DExperience environment, developed by Dassault Systémes.
... Other works carried out 3-D digital virtual models of ancient heritage monuments from onsite data, developing photogrammetry and especially focusing on data acquisition techniques and color processing methods (Remondino, 2011;Barazzetti, 2010). Some authors obtained a very efficient results integrating various "real-based" modeling methodologies (Fassi, 2011). In modeling, interesting approaches address to produce a digital document that combines metric and photographic data and historical data in a 3D textured model becoming a theoretical model (Lo Buglio, 2012 or 3D models that recognise the rules of construction becoming access point to architectural criticism (De Luca et al., 2011;. ...
... Thus, integrated methods are proposed in order to overcome the limitations [16][17][18]. In [19], two types of Milan Cathedral's main spire structure were individually reconstructed using different methods. The first type are mostly regular shapes, they were reconstructed by a model-driven method. ...
The ancient roof decorative components of the official-style architectures from the Ming and Qing dynasties in China hold both physical and symbolic significance. These roof structures are the essential objects in three-dimensional (3D) modeling of ancient architectures for traditional Chinese cultural preservation. Although ancient architectures can be surveyed by a 3D laser scanner, the complex geometry and diverse pattern of their roof decorative components make the 3D point cloud reconstruction challenging, or at some points, nearly impossible in a fully automated manner. In this paper, we propose a method to ensure that the 3D shape of each roof decorative component is accurately modeled. First, we establish a decorative components template library (or “template library” in short hereafter), which is the first of its kind for the roofs of Ming and Qing official-style architectures. The process of establishing the decorative components template library begins with a remote collection of survey data using a terrestrial laser scanner and digital camera. The next stage involves the design and construction of different 3D decorative components in the template library with reference to the manuscripts written in the Ming and Qing dynasties’ architectural pattern books. With the point cloud data collected on any Ming and Qing official-style architecture, we further propose a geo-registration mechanism to search for an optimal fitting of the decorative components from the template library on the collected point cloud automatically. Based on the experimental results, the accuracy of point cloud registration yields less than 0.02 m, which meets the accuracy of the 3D model at LoD 300 level. Time consumption is less than 5s and stable, for large volume computing capacity has good robustness. The proposed strategy provides a new way for the 3D modeling of large and clustered historical architectures, particularly with complex structures.
... In light of the necessity to create a complete 3D model of a heritage building, it is interesting to combine heterogeneous point clouds generated by these dierent sensors of the building's exterior and interior [Fassi et al., 2011]. Also in the interest of keeping the geometric quality, it is also important to devise a method of quality control for the resulting registered point cloud. ...
The documentation of built heritage has seen a significant development these past few decades due to advancements in new 3D sensors and 3D recording techniques. 3D data serve as reliable and tangible archive for historical sites and monuments. Since 3D data have such importance in the field of heritage documentation, quality control is paramount and must be performed before any point cloud processing is even planned to be conducted. The thesis is therefore divided into two parts. The first part concerned mainly the data acquisition and quality control of the point cloud data using the two techniques most commonly used, i.e. photogrammetry and laser scanning. A particular emphasis was also put on the integration of photogrammetry and laser scanning within the context of a multi-scalar documentation of a heritage site. The second part will address the processing of the resulting point cloud, particularly its segmentation and classification. The multi-scalar approach proposed in this thesis is an important point to note, as in many cases a historical building of interest is located in a historical neighbourhood; thus
the requirement for a multi-scalar segmentation. By combining these two parts, the thesis had attempted to address the 3D workflow of heritage sites in a holistic manner, from the 3D data acquisition up to the resulting point clouds' segmentation and classi cation into individual entities in various scale steps.
... The surveys created using these two techniques (especially TLS with the addition of data derived from CRP) are used for gathering information necessary for the preservation of cultural heritage, architectural and archaeological studies and analyses [23], and historical context analysis [24]. Documentation projects with data fusion are commonly described as case studies in cultural heritage projects, especially when large or complex scenarios are documented [16], [25]- [28]. Obviously, there are some limitations of the TLS and CRP techniques, but in fact, these methods are very complementary [29], [30]. ...
... The surveys created using these two techniques (especially TLS with the addition of data derived from CRP) are used for gathering information necessary for the preservation of cultural heritage, architectural and archaeological studies and analyses [23], and historical context analysis [24]. Documentation projects with data fusion are commonly described as case studies in cultural heritage projects, especially when large or complex scenarios are documented [16], [25]- [28]. Obviously, there are some limitations of the TLS and CRP techniques, but in fact, these methods are very complementary [29], [30]. ...
... Traditionally, manual modeling techniques have been necessary to produce models with sufficient accuracy and completeness [19]. Manual modeling requires significant time and labor resources, particularly if using data from multiple sources [20], and the automatic modeling of the built environment has been widely explored as an alternative approach [9,12,21,22]. Approaches for the automatic generation of indoor models include surface-based methods [23], primarily for visualization purposes, fitting volumetric primitives to the measurement data, or constructing the room based on a shape grammar [24]. ...
The automated 3D modeling of indoor spaces is a rapidly advancing field, in which recent developments have made the modeling process more accessible to consumers by lowering the cost of instruments and offering a highly automated service for 3D model creation. We compared the performance of three low-cost sensor systems; one RGB-D camera, one low-end terrestrial laser scanner (TLS), and one panoramic camera, using a cloud-based processing service to automatically create mesh models and point clouds, evaluating the accuracy of the results against a reference point cloud from a higher-end TLS. While adequately accurate results could be obtained with all three sensor systems, the TLS performed the best both in terms of reconstructing the overall room geometry and smaller details, with the panoramic camera clearly trailing the other systems and the RGB-D offering a middle ground in terms of both cost and quality. The results demonstrate the attractiveness of fully automatic cloud-based indoor 3D modeling for low-cost sensor systems, with the latter providing better model accuracy and completeness, and with all systems offering a rapid rate of data acquisition through an easy-to-use interface.
... To support the exceptional maintenance activities, a number of focussed survey operations were conducted in the last 10 years, producing 3D data and 2D classical representation at a 1:50 scale for the Main Spire, the altars of the transept, and the Dome Cladding [42]. More recently, detailed point clouds of the entire Cathedral at an average and uniform resolution of 5 mm ( Figure 2 and Table 1) were produced using Terrestrial Laser Scanning (TLS) for the interior spaces [43], photogrammetry for the exteriors [44] and integrating both techniques in narrow service spaces [45,46]. ...
The recent years saw an extensive use of 3D point cloud data for heritage documentation, valorisation and visualisation. Although rich in metric quality, these 3D data lack structured information such as semantics and hierarchy between parts. In this context, the introduction of point cloud classification methods can play an essential role for better data usage, model definition, analysis and conservation. The paper aims to extend a machine learning (ML) classification method with a multi-level and multi-resolution (MLMR) approach. The proposed MLMR approach improves the learning process and optimises 3D classification results through a hierarchical concept. The MLMR procedure is tested and evaluated on two large-scale and complex datasets: the Pomposa Abbey (Italy) and the Milan Cathedral (Italy). Classification results show the reliability and replicability of the developed method, allowing the identification of the necessary architectural classes at each geometric resolution.
... Of course, we must also remember that the use of photogrammetric methods has been a core component of some of the most genuinely groundbreaking technical research undertaken within the field of heritage surveying. For example, work undertaken by the 3D Survey Group in Milan (Fassi, Achille & Fregonese, 2011) has embraced the notion of there being numerous tools and techniques open to the practitioner, and where the choice of technique for any particular project or task needs to be driven by a combination of practicalities, access, cost and the anticipated purpose of the data once collected. Indeed, research undertaken pertaining to photogrammetry, and particularly within a heritage setting, has been able to establish that the method, when undertaken under controlled conditions, is capable of producing models and results of sufficient accuracy to be used within building maintenance planning, heritage recording and for communication to a wide audience. ...
Modelling and visualisation of the built heritage has become an area where digital tools and techniques have become pervasive. This extends across all stages and aspects of heritage projects, and has come to include the culture of data pertaining to physical objects and environments, the subsequent uses to which that data may be put, and the manner in which stakeholder groups engage in debate, discussion and participatory decision-making. This paper provides a critical discussion of the implications of these developments and the associated technologies, and argues that what might appear to be ‘stages’ of a project should be regarded as a cycle, which embeds social and qualitative aspects of the built heritage as key components. The paper aims to contribute to the debate regarding how we can embrace developing technologies within heritage study, and how application of the technology can help to foster deeper engagement in heritage, and across society.
... Starting in 2010, the 3D survey group of the Politecnico di Milano developed a prototype of an HBIM (Building Information Model for Cultural Heritage) system for the maintenance of the Veneranda Fabbrica del Duomo di Milano (Fassi et al. 2011). This experiment worked as a pilot project to develop a more general information system (BIM3DSG), to be proposed as a standard fruition and valorization procedure in the world of cultural heritage, using 3D as the basis of informative systems (Rechichi et al. 2016). ...
This open access book explores key issues and presents recent case studies in areas of importance for the transition to a circular model of development in emerging African countries that will minimize resource consumption and waste production. The topics covered include the development of sustainable housing models, energy and environmental issues in building design and technical systems, recycling for a sustainable future, models for humanitarian emergencies, and low-cost and web-based digital tools with applications in architecture and archaeology.
The aim is to contribute to a necessary paradigm shift with respect to urban planning and usage of territories, moving from a linear urban metabolism based on the “take, make, dispose” approach to a circular metabolism. Such a change requires a focus on the relationship between the architectural, urban, and physical aspects of new developments, climate, and energy demand, as well as the identification and integration of strategies and infrastructures to achieve a high level of efficiency and self-sufficiency. The book will appeal to all with an interest in sustainable development in the African context.
The integration of 3D laser scanning and digital photogrammetry in the architecture, engineering, and construction (AEC) industry has facilitated high-quality architectural surveys. However, the processes remains constrained by significant costs, extensive manual labor, and accuracy issues associated with manual data processing. This article addresses these operational challenges by introducing automated Building Information Modeling (BIM) techniques that minimize manual input through the use of Dynamo for Autodesk Revit. We developed algorithms that efficiently convert point cloud data into accurate BIM models, enhancing productivity and reducing the potential for errors. The application of these algorithms is analyzed in a case study of the Old Lifeguard Station of Fuseta, showcasing notable reductions in modeling time and improvements in accuracy. The findings suggest that automated scan-to-BIM methods could provide a viable solution for enhancing BIM workflows across the industry, with the potential for wider adoption given their impact on efficiency and model quality.
Conservation of Cultural Heritage is a key topic and structural changes and damages can affect the structural behaviour of Cultural Heritage artefacts and buildings. Considering that the application of technologies can help in preserving, conserving and restoring ancient structures, it is mandatory to find the best pipeline to produce the correct analysis that can be provided with the use of Finite Element Analysis, a well-known technique used in modelling stress behaviour of objects and structures. The necessary workflow invests and involves design experts enabled to mathematically master the potential of models that pass from interpretation to design control. Following the principles of good experimental practice, the typical workflow involves the use of CAD 3D models made by Non-Uniform Rational B-splines (NURBS) surfaces, representing the ideal shape of the object to be simulated. Conversely, when applied to 3D models of Cultural Heritage, often altered by the time passed since their original creation, the representation with a schematic CAD model may introduce an excessive level of approximation leading to wrong simulation results. The focus of this work is to present a method based on retopology, hence on quadrangular element instead of triangles. Such process aims at generating the most accurate 3D representation of a real artefact from highly accurate 3D models derived from image-based and range—based techniques, maintaining the accuracy of the high—resolution polygonal models in the solid ones to be created for FEA. A proper pipeline can help to carry out the necessary interventions and perform virtual restoration prior to the physical one.
It is likely that Autonomous Vehicles (AVs) will have significant social, cultural, spatial and environmental implications and the interaction between humans, automated vehicles and physical environment will provide an array of challenges. This paper aims to explore use of innovative visualisation approaches, to communicate and foster discussion to anticipate possible scenarios involving AVs. It is argued that such an approach might be used to help conceptualise human experiences with the potential to enhance public engagement and understanding of the complex human-machine associations and open a dialogue with potential end users.
Presenting the journeys from different perspectives and reconceptualising the context through the eyes of AVs emphasised the nuances of experience between the machines, urban space and human bodies. Unexpected user-technology interactions and experiences will emerge as humans are not always sensible and passive followers and can be apprehensive when it comes to accepting such a novel technology as self-driving vehicles on the roads.
The focus applied in the methodology and data capture was on inclusivity of data, and an aspiration to capture not only movement but also noise and human experience of a space. The integration of AVs on public roads will rely on technical innovation to ensure that vehicles can safely operate in a practical sense yet, the study of the perceptual and ethical effects of new technology and potential influences on society via engaging the general public in the process will help to manage expectations and create platforms for mutual learning.
Built cultural heritage is under constant threat due to environmental pressures, anthropogenic damages, and interventions. Understanding the preservation state of monuments and historical structures, and the factors that alter their architectural and structural characteristics through time, is crucial for ensuring their protection. Therefore, inspection and monitoring techniques are essential for heritage preservation, as they enable knowledge about the altering factors that put built cultural heritage at risk, by recording their immediate effects on monuments and historic structures. Nondestructive evaluations with close-range sensing techniques play a crucial role in monitoring. However, data recorded by different sensors are frequently processed separately, which hinders integrated use, visualization, and interpretation. This article’s aim is twofold: i) to present an overview of close-range sensing techniques frequently applied to evaluate built heritage conditions, and ii) to review the progress made regarding the fusion of multi-sensor data recorded by them. Particular emphasis is given to the integration of data from metric surveying and from recording techniques that are traditionally non-metric. The article attempts to shed light on the problems of the individual and integrated use of image-based modeling, laser scanning, thermography, multispectral imaging, ground penetrating radar, and ultrasonic testing, giving heritage practitioners a point of reference for the successful implementation of multidisciplinary approaches for built cultural heritage scientific investigations.
p class="VARKeywords">The accurate graphic survey of an archaeological site is fundamental for its analysis and research. Furthermore, if this site is to be covered by a building and will not be accessible or visible, its documentation is essential, not only to continue with the research, but also to disseminate and enhance the discoveries. An example of this is the " Hoya de los Molinos " archaeological site in Caravaca de la Cruz (Region of Murcia, Spain). This is where the first mark of the wheel of a Roman vertical watermill in the Iberian Peninsula has been found. This fact is crucial because remains of Roman vertical-wheeled watermills have been found across the Mediterranean but not in the Iberian Peninsula. Moreover, the fact that this watermill still has all its structural elements makes this archaeological site in Caravaca de la Cruz very interesting. Due to these facts, it is essential to disseminate this discovery, so that it can be recognized and considered as archaeological and cultural heritage. To that end, the researchers have carried out a three-dimensional (3D) reconstruction of the most characteristic elements, such as the vertical wheel, the gears that allowed grinding the grain, and the building protecting them. A virtual recreation was carried out, based on the historical and building research, which is displayed in an explanatory video. Furthermore, two reproductions were created: one made to scale of the archaeological site with a 3D printer and another one of the hypothetical structure of the Roman watermill. To achieve this result, historians, archaeologists and engineers have collaborated, thus enabling not only its adequate dissemination, but also its accurate documentation, in an inclusive manner. Thanks to all the work that this paper describes, the Roman watermill found in Caravaca de la Cruz can be known, studied and assessed.
Highlights:
The first Roman watermill in the Iberian Peninsula has been found with all its structural elements, from the imprints left in the stone by the wheel.
Virtual reconstruction of the first vertical wheel watermill discovered in Hispania has been made.
An animated video of the hydraulic watermill gears performance has been created for documentation and dissemination.
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In recent years, a complete 3D mapping of the Cultural Heritage (CH) has become fundamental before every other action could follow. Different survey techniques outputs could be combined in a 3D point cloud, completely describing the geometry of even the most complex object. These data very rich in metric quality can be used to extract 2D technical elaborations and advanced 3D representations to support conservation interventions and maintenance planning. The case of Milan Cathedral is outstanding. In the last 12 years, a multi-technique omni-comprehensive survey has been carried out to extract the technical representations that are used by the Veneranda Fabbrica (VF) del Duomo di Milano to plan its maintenance and conservation activities. Nevertheless, point cloud data lack structured information such as semantics and hierarchy among parts, fundamentals for 3D model interaction and database (DB) retrieval. In this context, the introduction of point cloud classification methods could improve data usage, model definition and analysis. In this paper, a Multi-level Multi-resolution (MLMR) classification approach is presented and tested on the large dataset of Milan Cathedral. The 3D point model, so structured, for the first time, is used directly in a Mixed Reality (MR) environment to develop an application that could benefit professional works, allowing to use 3D survey data on-site, supporting VF activities.
Purpose
– This paper aims to present a systematic approach for building information modelling (BIM) implementation for architectural SMEs at the organizational level
Design/methodology/approach
– The research is undertaken through a knowledge transfer partnership (KTP) project between the University of Salford and John McCall Architects (JMA) a SME based in Liverpool. The overall aim of the KTP is to develop lean design practice through BIM adoption. The BIM implementation approach uses a socio‐technical view, which does not only consider the implementation of technology but also considers the socio‐cultural environment that provides the context for its implementation. The action research oriented qualitative and quantitative research is used for discovery, comparison, and experimentation as it provides “learning by doing”.
Findings
– The strategic approach to BIM adoption incorporated people, process and technology equally and led to capacity building through the improvements in process, technological infrastructure and upskilling of JMA staff to attain efficiency gains and competitive advantages.
Originality/value
– The paper introduces a systematic approach for BIM adoption based on the action research philosophy and demonstrates a roadmap for BIM adoption at the operational level for SME companies.
URL: http://vsmm2008.euromed2010.eu/vsmm2008/e_Proceedings/papers/projectpapers.pdf#page=57
The article reports about a multi-resolution approach developed for the 3D modeling of the entire Roman Forum in Pompei, Italy. The archaeological area, approximately 150 x 80 m, contains more than 350 finds spread all over the forum as well as larger mural structures of previous buildings and temples. The interdisciplinary 3D modeling work consists of a multi-scale image- and range-based digital documentation method developed to fulfill all the surveying and archaeological needs and exploit all the potentialities of the actual 3D modeling techniques. Data’s resolution spans from few decimeters down to few millimeters. The employed surveying methodologies have pros and cons which will be addressed and discussed. The preliminary results of the integration of the different 3D data in seamlessly textured 3D model, will be presented.
In this paper we would like to present a possible operating way to survey and model a very complex architecture, integrating different kinds of instrumentation and modeling methods. In particular we would like to convoy the attention on a possible measure and data elaboration procedure that allows collecting and post-elaborating data in a short time in order to both extract classical architectural products, such as sections and profiles, and to build complete and accurate 3D models. The necessity is to structure multi-data source procedure buds inside a five years project (still in progress) with the goal to survey and three-dimensionally model the Main Spire of Milan Cathedral. It is a very complex "object" and, for this reason, it can be considered a very challanging and useful test field for the new 3D survey technologies and, in particular, for the various "real-based" modeling methodologies. In the paper are described the survey workflow and the relative elaboration steps, focusing on the problems and justifying the key choices.
This paper describes a structure from motion and recognition paradigm for generating 3D models from 2D sets of images. In particular we consider the domain of architectural photographs. A model based approach is adopted with the architectural model built from a "Lego kit" of parameterised parts. The approach taken is different from tradi-tional stereo or shape from X approaches in that identification of the parameterised components (such as windows, doors, buttresses etc) from one image is combined with parallax information in order to generate the 3D model. This model based approach has two main benefits: first, it allows the inference of shape and texture where the evidence from the images is weak; and second, it recovers not only geometry and texture but also an interpretation of the model, which can be used for automatic enhancement techniques such as the application of reflective textures to windows.
Camera calibration has always been an essential component of photogrammetric measurement, with self-calibration nowadays being an integral and routinely applied operation within photogrammetric triangulation, especially in high-accuracy close-range measurement. With the very rapid growth in adoption of off-the-shelf digital cameras for a host of new 3D measurement applications, however, there are many situations where the geometry of the image network will not support robust recovery of camera parameters via on-the-job calibration. For this reason, stand-alone camera calibration has again emerged as an important issue in close-range photogrammetry, and it also remains a topic of research interest in computer vision. This paper overviews the current approaches adopted for camera calibration in close-range photogrammetry and computer vision, and discusses operational aspects for self-calibration. Also, the results of camera calibrations using different algorithms are summarized. Finally, the impact of chromatic aberration on modelled radial distortion is touched upon to highlight the fact that there are still issues of research interest in the photogrammetric calibration of consumer-grade digital cameras.
The importance of cultural and natural heritage documentation is well recognized at international level, and there is an increasing
pressure to document and preserve heritage also digitally. The continuous development of new sensors, data capture methodologies,
and multi-resolution 3D representations and the improvement of existing ones can contribute significantly to the 3D documentation,
conservation, and digital presentation of heritages and to the growth of the research in this field. The article reviews some
important documentation requirements and specifications, the actual 3D surveying and modeling techniques and methodologies
with their limitations and potentialities as well some visualization issues involved in the heritage field. Some examples
of world heritage sites 3D documentation are reported and discussed.
KeywordsPhotogrammetry-Laser scanning-Multi-resolution-Multi-sensor-Heritage sites
The advent of high-resolution digital cameras and sophisticated multi-view stereo algorithms offers the promise of unprecedented
geometric fidelity in image-based modeling tasks, but it also puts unprecedented demands on camera calibration to fulfill
these promises. This paper presents a novel approach to camera calibration where top-down information from rough camera parameter
estimates and the output of a multi-view-stereo system on scaled-down input images is used to effectively guide the search
for additional image correspondences and significantly improve camera calibration parameters using a standard bundle adjustment
algorithm (Lourakis and Argyros 2008). The proposed method has been tested on six real datasets including objects without salient features for which image correspondences
cannot be found in a purely bottom-up fashion, and objects with high curvature and thin structures that are lost in visual
hull construction even with small errors in camera parameters. Three different methods have been used to qualitatively assess
the improvements of the camera parameters. The implementation of the proposed algorithm is publicly available at Furukawa
and Ponce (2008b).
This paper proposes a novel algorithm for calibrated multi-view stereopsis that outputs a (quasi) dense set of rectan- gular patches covering the surfaces visible in the input images. This algorithm does not require any initialization in the form of a bounding volume, and it detects and discards automatically out- liers and obstacles. It does not perform any smoothing across nearby features, yet is currently the top performer in terms of both coverage and accuracy for four of the six benchmarkdatasets pre- sented in (20). The keys to its performance are effective tech- niques for enforcing local photometric consistency and global visibility constraints. Stereopsis is implemented as a match, ex- pand, and filter procedure, starting from a sparse set of matched keypoints, and repeatedly expanding these to nearby pixel corre- spondences before using visibility constraints to filter away false matches. A simple but effective method for turning the resulting patch model into a mesh appropriate for image-based modeling is also presented. The proposed approach is demonstrated on vari- ous datasets including objects with fine surface details, deep con- cavities, and thin structures, outdoor scenes observed from a re- stricted set of viewpoints, and "crowded" scenes where moving obstacles appear in different places in multiple images of a static structure of interest.
This paper introduces an approach for enabling existing multi-view stereo methods to operate on extremely large unstructured photo collections. The main idea is to decompose the collection into a set of overlapping sets of photos that can be processed in parallel, and to merge the resulting reconstructions. This overlapping clustering problem is formulated as a constrained optimization and solved iteratively. The merging algorithm, designed to be parallel and out-of-core, incorporates robust filtering steps to eliminate low-quality reconstructions and enforce global visibility constraints. The approach has been tested on several large datasets downloaded from Flickr.com, including one with over ten thousand images, yielding a 3D reconstruction with nearly thirty million points.
Contemporarily some firms in the construction industry are attempting to adopt a BIM method of working. Each of these attempts reflects a varying BIM adoption philosophy and inevitably different BIM technologies, implementation strategies and roadmaps. On the other hand, all these attempts are often motivated to attain competitive advantages for product delivery in the market place. The question of what the best method of adopting BIM has not been answered yet. That is to say, it is required to identify a standard method that will benchmark the different BIM adoption cases by comparing the efficiency gains in these cases: a standard benchmarking method can help the stakeholders to decide on the most appropriate strategies for themselves.
This paper explains the live experience of BIM adoption in a KTP (Knowledge Transfer Partnership) project, undertaken between the University of Salford and John McCall Architects practicing in the housing and regeneration fields, with a particular focus on a set of KPIs that have been developed and tested through the action research strategy in the project. Weighting of these KPI’s has been developed from an architectural business perspective
This paper proposes a novel algorithm for multiview stereopsis that outputs a dense set of small rectangular patches covering the surfaces visible in the images. Stereopsis is implemented as a match, expand, and filter procedure, starting from a sparse set of matched keypoints, and repeatedly expanding these before using visibility constraints to filter away false matches. The keys to the performance of the proposed algorithm are effective techniques for enforcing local photometric consistency and global visibility constraints. Simple but effective methods are also proposed to turn the resulting patch model into a mesh which can be further refined by an algorithm that enforces both photometric consistency and regularization constraints. The proposed approach automatically detects and discards outliers and obstacles and does not require any initialization in the form of a visual hull, a bounding box, or valid depth ranges. We have tested our algorithm on various data sets including objects with fine surface details, deep concavities, and thin structures, outdoor scenes observed from a restricted set of viewpoints, and "crowded" scenes where moving obstacles appear in front of a static structure of interest. A quantitative evaluation on the Middlebury benchmark shows that the proposed method outperforms all others submitted so far for four out of the six data sets.
This paper describes a structure from motion and recognition paradigm for generating 3D models from 2D sets of images. In particular we consider the domain of architectural photographs. A model based approach is adopted with the architectural model built from a “Lego kit” of parameterised parts. The approach taken is different from traditional stereo or shape from X approaches in that identification of the parameterised components (such as windows, doors, buttresses etc) from one image is combined with parallax information in order to generate the 3D model. This model based approach has two main benefits: first, it allows the inference of shape and texture where the evidence from the images is weak; and second, it recovers not only geometry and texture but also an interpretation of the model, which can be used for automatic enhancement techniques such as the application of reflective textures to windows
Provides an overview of image matching techniques. Image matching is inherently an ill-posed problem, and additional assumptions and constraints have to be introduced to make it well-posed. The individual modules of some existing matching algorithms are described and analyzed in detail. The matching strategy plays a decisive role for the success of any particular algorithm. A hierarchical approach combined with epipolar geometry and a highly redundant set of conjugate primitives is found to be very important in order to control the computational complexity and to ensure a high reliability for the results.
This work is part of the project "Development of Geographic Information Systems at the Acropolis of Athens". Within this project one of the aims is the generation of a textured, high-resolution, accurate D model of the Erechtheion and a realistic computer animation. For most parts, we used a medium-range time-of-flight (TOF) phase-based laser scanner with minimum lateral data spacing of 1 mm and depth uncertainty of 0.2 mm. We also used high-resolution digital images for image-based reconstruction on some parts and for texture mapping. We present data capture, processing, and model generation techniques with emphasis on the encountered problems and solutions when dealing with a large complex structure, huge datasets, and field work under time constraints and challenging conditions. The experience gained, and the tools adapted for some tasks, will be valuable for other large-scale D modelling projects.
An approach is described for automatic relative orientation of a stereopair of digital aerial images. The concept and the implementation are based on practical conditions with respect to available a priori knowledge, speed of computation, and obtainable accuracy. Feature-based image matching using point features extracted with a modified version of the Moravec operator and a coarse-to-fine strategy are incorporated into the approach. In higher image pyramid levels, where images are small in size and of low resolution, the entire model area is searched for interest points. In lower levels, window tracking is carried out in order to speed up the entire procedure and to stabilize the final results. In all levels, matching is based on geometric as well as radiometric constraints. The approach was developed as one of the automation-oriented software components of a digital photogrammetric workstation. Results obtained from ten aerial image pairs with scales ranging from 1:3,000 to 1:34,000 and scanned with a pixel size of 15 μm, thus yielding some 235 Megabytes per image, are presented. In each case, more than 150 well distributed points were extracted. The obtained root-mean-square standard deviations of the image coordinates consistently lie between 3.2 and 3.6 μm or 0.21 and 0.24 pixels. A human operator checked the resulting models on an analytical plot ter. The models were found to be free of y-parallax. The elapsed computing time was approximately 4 minutes per image pair on a Silicon Graphics Iris Indigo workstation with R4000 processor. This means that the procedure runs as fast as, if not faster than, a human operator can carry out the relative orientation while yielding the same level of accuracy. Thus, it could be shown that the presented method for automatic relative orientation is operational for practical applications.
An automatic aerotriangulation system is described. Its design and development have been made to possibly meet every requirement from photogrammetric practice. The system consists of five components, i.e. block preparation, fully automatic tie point determination, semi-automatic control point measurement, interface to diverse block adjustment programs and block post-processing. A relational data base takes care of communications among individual components. The fully automatic tie point determination plays a key role in the whole system. Its realization follows the principle of image connection and thus exhausts the technical potential to reach the highest level of automation. Intensive operational tests were carried out using diverse image blocks with various configurations from photogrammetric practice. Different terrain types and ground covering as well as various camera focal lengths and image scales were considered. On average 200–500 tie points were determined per image. The achieved standard deviation of image coordinates amounts to 0.2–0.5 pixel. The computation time for the tie point determination is about 5 min per image. It was proven that automatic aerotriangulation provides higher reliability of results and much more economy to the photogrammetric practice than ever before. The system is now in daily operation in practice.
We present a model that allows to directly integrate X3D nodes into HTML5 DOM content. This model tries to fulfill the promise of the HTML5 specification, which references X3D for declarative 3D scenes but does not define a specific integration mode. The goal of this model is to ease the integration of X3D in modern web applications by directly mapping and synchronizing live DOM elements to a X3D scene model. This is a very similar approach to the current SVG integration model for 2D graphics. Furthermore, we propose a framework that includes a new X3D Profile for the DOM integration. This profile should make implementation simple, but in addition we show that the current X3D runtime model still scales well. A detailed discussion includes DOM integration issues like events, namespaces and scripting. We finally propose an implementation framework that should work with multiple browser frontends (e.g. Firefox and WebKit) and different X3D runtime backends. We hope to connect the technologies and the X3D/ W3C communities with this proposal and outline a model, how an integration without plugins could work. Moreover, we hope to inspire further work, which could lead to a native X3D implementation in browsers similar to the SVG implementations today.
is that these approaches will one day allow virtual tourism of the world's interesting and important sites. We present a system for interactively browsing and exploring large unstructured collections of photographs of a scene using a novel 3D interface. Our system consists of an image-based modeling front end that automatically computes the viewpoint of each photo-graph as well as a sparse D model of the scene and image to model correspondences. Our photo explorer uses image-based rendering techniques to smoothly transition between photographs, while also enabling full D navigation and exploration of the set of images and world geometry, along with auxiliary information such as overhead maps. Our system also makes it easy to construct photo tours of scenic or historic locations, and to annotate image details, which are automatically transferred to other relevant images. We demon-strate our system on several large personal photo collections as well as images gathered from Internet photo sharing sites. CR Categories: H. 5.1 [Information Interfaces and Presentation]: Multimedia Information Systems, Arti cial, augmented, and vir-tual realities I. 2.10 [Arti cial Intelligence]: Vision and Scene Understanding, Modeling and recovery of physical attributes Keywords: image-based rendering, image-based modeling, photo browsing, structure from motion
An important application of laser range sensing is found in the 3D scanning and modelling of heritage collections, and of sculptures in particular. Since a significant proportion of the statues in the world's museums is composed of marble, the optical properties of this material under laser range sensing need to be understood. Marble's translucency and heterogeneous structure produce significant bias and increased noise in the geometric measurement. Experiments on a sample of Carrara Statuario marble highlight the relationship between the laser spot diameter and the estimated noise levels in the geometric measurements. A bias in the depth measurement is also observed. These phenomena are believed to result from scattering on the surface of small crystals at or near the surface. La télémétrie laser comporte d'importantes applications dans le domaine de la modélisation et de la numérisation 3D des collections patrimoniales en général, et des sculptures en particulier. Comme une partie importante des statues qui sont exposées dans les musées un peu partout dans le monde sont faites de marbre, il est nécessaire de comprendre les propriétés optiques de ce matériau dans le contexte de la télémétrie laser. La translucidité du marbre et sa structure hétérogène donnent lieu à des parasites et à des distorsions importantes lors des mesures géométriques. Les expériences qui ont été effectuées sur des statues en marbre de Carrare mettent en évidence la relation qui existe entre le diamètre du faisceau laser et le niveau estimé des parasites dans les mesures géométriques. On constate également une erreur systématique dans les mesures de profondeur. On croit que ces phénomènes résultent de la diffusion superficielle de petits cristaux présents sur la surface du matériau ou à proximité de cette dernière.
this paper we report the results from the comparison between digital photogrammetry and laser scanning techniques applied to the survey of the outside of the ancient church of Pozzoveggiani, located in the sourrounding of Padua (Italy)
Integration of traditional and innovative technologies of survey and modelling of cultural heritage
- F Fassi
Photogrammetry and ground-based laser scanning: assessment of metric accuracy of the 3D model of Pozzoveggiani Church. FIG Working Week, The Olympic Spirit in Surveying
- A Guarnieri
- A Vettore
- F Remondino
Il modello fisico come forma di rappresentazione
- G Guidi
Multiple data source for survey and modelling of very complex architecture. International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences
- F Fassi
- C Achille
- L Fregonese
- C Monti
Digital camera calibration methods: consideration and comparisons. International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences
- F Remondino
- C Fraser
Applicazioni di rilievo multi‐sensore per il restauro della guglia Maggiore del Duomo di Milano
- Gaudio F.