1,720,963 research outputs found
A Comprehensive Understanding of Machine Learning and Deep Learning Methods for 3D Architectural Cultural Heritage Point Cloud Semantic Segmentation
No full textAs a result of the development of Artificial Intelligence (AI) techniques, in recent years, machine learning (ML) and deep learning (DL) approaches have been widely used to semantically enrich 3D architectural cultural heritage (ACH) point clouds. While existing approaches for analyzing and interpreting point clouds continue to improve, the generalizability of pre-trained ML and DL methods to various types of historic buildings remains uncertain. In this context, a comprehensive understanding of both methodologies can enable us to make more effective use of AI techniques in the ACH domain (e.g., data exploitation, model definition, analysis, and preservation). This work presents and compares two very different approaches for the 3D ACH semantic segmentation task. Specifically, we train and test a ML method based on the Random Forest (RF) classifier on the point cloud of three chapels part of the “Sacromonte Calvario di Domodossola” and on the two test scenes of the ArCH dataset. Then, we employ dynamic graph convolutional neural network (DGCNN) as our DL method, training on the ArCH dataset and testing on both the two unseen test scenes of the ArCH dataset and on the “Sacrimonti” chapel point clouds. We provide empirical experiments to illustrate the efficiency of applying ML and DL methodologies to ACH point clouds. Following that, the advantages and limitations of these two approaches are evaluated through a systematic study of the classification results. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG
Machines Learning for Mixed Reality
No full textIn 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
A Multilevel Multiresolution Machine Learning Classification Approach: A Generalization Test on Chinese Heritage Architecture
Full text linkIn recent years, the investigation and 3D documentation of architectural heritage has made an efficient digitalization process possible and allowed for artificial intelligence post-processing on point clouds. This article investigates the multilevel multiresolution methodology using machine learning classification algorithms on three point-cloud projects in China: Nanchan Ssu, Fokuang Ssu, and Kaiyuan Ssu. The performances obtained by extending the prediction to datasets other than those used to train the machine learning algorithm are compared against those obtained with a standard approach. Furthermore, the classification results obtained with an MLMR approach are compared against a standard single-pass classification. This work proves the reliability of the MLMR classification of heritage point clouds and its good generalizability across scenarios with similar geometrical characteristics. The pros and cons of the different approaches are highlighted
A Hierarchical Machine Learning Approach for Multi-Level and Multi-Resolution 3D Point Cloud Classification
Full text linkThe 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
VR for Cultural Heritage. A VR-WEB-BIM for the future maintenance of Milan’s Cathedral.
Full text linkThe work presented here is the final step of a multidisciplinary research project conducted on the Milan Cathedral for eight years (2008–2015). Three main topics, consequentially related, will be here addressed: (i) the survey of the structure, meant to update the old drawings; (ii) the construction of an accurate and detailed 3D model to be used to produce measurements at a 1:20–1:50 representation scale; (iii) the development of a Building Information System (BIM) to collect all the data relating to the restoration projects, as well as all information relating to past, current and future maintenance activities of the cathedral. The result of this research project is a complex and accurate digital 3D model of the main spire of the cathedral and of other parts of the building. This model can be visualized, navigated and used by the Veneranda Fabbrica technicians as an info-data catalogue, thanks to a common web browser connected with the remote BIM System Server and the modelling software where ad hoc I/O plugins are implemented. The last step of this long project was to take advantage of the nascent potential of immersive visualization techniques and to transpose the BIM system in a VR environment, thus obtaining two main results. The first was a high-appeal visualization system that allows a virtual visit of the Main Spire of the cathedral, the building’s highest part that has been closed to visitors since the beginning of the XX century. The second was the possibility to use this technology to virtually explore the cathedral from a technical point of view: by using an immersive visualization technology, operators can improve their understanding of the structure and obtain real-time information about the state of conservation, including current and past maintenance activities, in a sort of “augmented reality system in a virtual environment”
A HYBRID MODEL FOR THE REVERSE ENGINEERING OF THE MILAN CATHEDRAL. CHALLENGES AND LESSON LEARNT
Full text linkCultural 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
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Integrated Laser Scanner Techniques to Produce High-Resolution DTM of Vegetated Territory
Full text linkThe paper presents the first part of a research project concerning the creation of 3D terrain models useful to understand landslide movements. Thus, it illustrates the creation process of a multi-source high-resolution Digital Terrain Model (DTM) in very dense vegetated areas obtained by integrating 3D data coming from three sources, starting from long and medium-range Terrestrial Laser Scanner up to a Backpack Indoor Mobile Mapping System. The point clouds are georeferenced by means of RKT GNSS points and automatically filtered using a Cloth Simulation Filter algorithm to separate points belonging to the ground. Those points are interpolated to produce the DTMs which are then mosaicked to obtain a unique multi-resolution DTM that plays a crucial role in the detection and identification of specific geological features otherwise visible. Standard deviation of residuals of the DTM varies from 0.105 m to 0.176 m for Z coordinate, from 0.065 m to 0.300 m for X and from 0.034 m to 0.175 m for Y. The area under investigation belongs to the Municipality of Piuro (SO) and includes both the town and surrounding valley. It was affected by a dramatic landslide in 1618 that destroyed the entire village. Numerous challenges have been faced, caused both by the characteristics of the area and the processed data. The complexity of the case study turns out to be an excellent test bench for the employed technologies, providing the opportunity to precisely identify the needed direction to obtain future promising results
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
