GLOBE BASED 3D GIS SOLUTIONS FOR VIRTUAL HERITAGE

During the last years, many solutions have been proposed for 3D Virtual Heritage representations. Recently, also new technologies for online gaming evolved, based on javascript libraries (WebGL), used to create and publish virtual interactive environments. They are based on recent Web browser’s functionalities, surpassing some limitations of VRML technologies. On the side of geospatial information, technology has evolved from desktop GIS to 2D WebGIS and globe applications. The use of globe applications is, today, very diffused due to its immediate and at the same time impressive representation of the earth surface and territories. These technologies have been, also, applied to Virtual Heritage 3D reconstructions, to improve the fruition of Cultural Heritage (CH), with the achievement of interesting results. The topic of this paper is the experimentation on the fusion between globe based and gaming technologies (in our case WebGL) that allow achieving a more user-centric and powerful solution useful for publishing 3D geospatial information of CH on Web. This choice allows obtaining GIS oriented 3D models, typical of globe applications, and, at the same time, a more immersive exploration of CH and its surrounding environment. In particular, it also gives complementary text and multimedia information on the history, architectural features of each cultural good, based on querying of semantic information. The test field of the research is the construction of the 3D GIS virtual globe model of the Manfredonic Castle of Mussomeli (Sicily-Italy), developed for PON-NEPTIS EU Project, to compare open-source technologies and commercial proprietary applications

3D Spatial Data Infrastructures for web-based Visualization

In this thesis, concepts for developing Spatial Data Infrastructures with an emphasis on visualizing 3D landscape and city models in distributed environments are discussed. Spatial Data Infrastructures are important for public authorities in order to perform tasks on a daily basis, and serve as research topic in geo-informatics. Joint initiatives at national and international level exist for harmonizing procedures and technologies. Interoperability is an important aspect in this context - as enabling technology for sharing, distributing, and connecting geospatial data and services. The Open Geospatial Consortium is the main driver for developing international standards in this sector and includes government agencies, universities and private companies in a consensus process. 3D city models are becoming increasingly popular not only in desktop Virtual Reality applications but also for being used in professional purposes by public authorities. Spatial Data Infrastructures focus so far on the storage and exchange of 3D building and elevation data. For efficient streaming and visualization of spatial 3D data in distributed network environments such as the internet, concepts from the area of real time 3D Computer Graphics must be applied and combined with Geographic Information Systems (GIS). For example, scene graph data structures are commonly used for creating complex and dynamic 3D environments for computer games and Virtual Reality applications, but have not been introduced in GIS so far. In this thesis, several aspects of how to create interoperable and service-based environments for 3D spatial data are addressed. These aspects are covered by publications in journals and conference proceedings. The introductory chapter provides a logic succession from geometrical operations for processing raw data, to data integration patterns, to system designs of single components, to service interface descriptions and workflows, and finally to an architecture of a complete distributed service network. Digital Elevation Models are very important in 3D geo-visualization systems. Data structures, methods and processes are described for making them available in service based infrastructures. A specific mesh reduction method is used for generating lower levels of detail from very large point data sets. An integration technique is presented that allows the combination with 2D GIS data such as roads and land use areas. This approach allows using another optimization technique that greatly improves the usability for immersive 3D applications such as pedestrian navigation: flattening road and water surfaces. It is a geometric operation, which uses data structures and algorithms found in numerical simulation software implementing Finite Element Methods. 3D Routing is presented as a typical application scenario for detailed 3D city models. Specific problems such as bridges, overpasses and multilevel networks are addressed and possible solutions described. The integration of routing capabilities in service infrastructures can be accomplished with standards of the Open Geospatial Consortium. An additional service is described for creating 3D networks and for generating 3D routes on the fly. Visualization of indoor routes requires different representation techniques. As server interface for providing access to all 3D data, the Web 3D Service has been used and further developed. Integrating and handling scene graph data is described in order to create rich virtual environments. Coordinate transformations of scene graphs are described in detail, which is an important aspect for ensuring interoperability between systems using different spatial reference systems. The Web 3D Service plays a central part in nearly all experiments that have been carried out. It does not only provide the means for interactive web-visualizations, but also for performing further analyses, accessing detailed feature information, and for automatic content discovery. OpenStreetMap and other worldwide available datasets are used for developing a complete architecture demonstrating the scalability of 3D Spatial Data Infrastructures. Its suitability for creating 3D city models is analyzed, according to requirements set by international standards. A full virtual globe system has been developed based on OpenStreetMap including data processing, database storage, web streaming and a visualization client. Results are discussed and compared to similar approaches within geo-informatics research, clarifying in which application scenarios and under which requirements the approaches in this thesis can be applied

Interactive web-based visualization

The visualization of large amounts of data, which cannot be easily copied for processing on a user’s local machine, is not yet a fully solved problem. Remote visualization represents one possible solution approach to the problem, and has long been an important research topic. Depending on the device used, modern hardware, such as high-performance GPUs, is sometimes not available. This is another reason for the use of remote visualization. Additionally, due to the growing global networking and collaboration among research groups, collaborative remote visualization solutions are becoming more important. The additional use of collaborative visualization solutions is eventually due to the growing global networking and collaboration among research groups. The attractiveness of web-based remote visualization is greatly increased by the wide availability of web browsers on almost all devices; these are available today on all systems - from desktop computers to smartphones. In order to ensure interactivity, network bandwidth and latency are the biggest challenges that web-based visualization algorithms have to solve. Despite the steady improvements in available bandwidth, these improvements are still significantly slower than, for example, processor performance, resulting in increasing the impact of this bottleneck. For example, visualization of large dynamic data in low-bandwidth environments can be challenging because it requires continuous data transfer. However, bandwidth improvement alone cannot improve the latency because it is also affected by factors such as the distance between server and client and network utilization. To overcome these challenges, a combination of techniques is needed to customize the individual processing steps of the visualization pipeline, from efficient data representation to hardware-accelerated rendering on the client side. This thesis first deals with related work in the field of remote visualization with a particular focus on interactive web-based visualization and then presents techniques for interactive visualization in the browser using modern web standards such as WebGL and HTML5. These techniques enable the visualization of dynamic molecular data sets with more than one million atoms at interactive frame rates using GPU-based ray casting. Due to the limitations which exist in a browser-based environment, the concrete implementation of the GPU-based ray casting had to be customized. Evaluation of the resulting performance shows that GPU-based techniques enable the interactive rendering of large data sets and achieve higher image quality compared to polygon-based techniques. In order to reduce data transfer times and network latency, and improve rendering speed, efficient approaches for data representation and transmission are used. Furthermore, this thesis introduces a GPU-based volume-ray marching technique based on WebGL 2.0, which uses progressive brick-wise data transfer, as well as multiple levels of detail in order to achieve interactive volume rendering of datasets stored on a server. The concepts and results presented in this thesis contribute to the further spread of interactive web-based visualization. The algorithmic and technological advances that have been achieved form a basis for further development of interactive browser-based visualization applications. At the same time, this approach has the potential for enabling future collaborative visualization in the cloud.Die Visualisierung großer Datenmengen, welche nicht ohne Weiteres zur Verarbeitung auf den lokalen Rechner des Anwenders kopiert werden können, ist ein bisher nicht zufriedenstellend gelöstes Problem. Remote-Visualisierung stellt einen möglichen Lösungsansatz dar und ist deshalb seit langem ein relevantes Forschungsthema. Abhängig vom verwendeten Endgerät ist moderne Hardware, wie etwa performante GPUs, teilweise nicht verfügbar. Dies ist ein weiterer Grund für den Einsatz von Remote-Visualisierung. Durch die zunehmende globale Vernetzung und Kollaboration von Forschungsgruppen gewinnt kollaborative Remote-Visualisierung zusätzlich an Bedeutung. Die Attraktivität web-basierter Remote-Visualisierung wird durch die weitreichende Verfügbarkeit von Web-Browsern auf nahezu allen Endgeräten enorm gesteigert; diese sind heutzutage auf allen Systemen - vom Desktop-Computer bis zum Smartphone - vorhanden. Bei der Gewährleistung der Interaktivität sind Bandbreite und Latenz der Netzwerkverbindung die größten Herausforderungen, welche von web-basierten Visualisierungs-Algorithmen gelöst werden müssen. Trotz der stetigen Verbesserungen hinsichtlich der verfügbaren Bandbreite steigt diese signifikant langsamer als beispielsweise die Prozessorleistung, wodurch sich die Auswirkung dieses Flaschenhalses immer weiter verstärkt. So kann beispielsweise die Visualisierung großer dynamischer Daten in Umgebungen mit geringer Bandbreite eine Herausforderung darstellen, da kontinuierlicher Datentransfer benötigt wird. Dennoch kann die alleinige Verbesserung der Bandbreite keine entsprechende Verbesserung der Latenz bewirken, da diese zudem von Faktoren wie der Distanz zwischen Server und Client sowie der Netzwerkauslastung beeinflusst wird. Um diese Herausforderungen zu bewältigen, wird eine Kombination verschiedener Techniken für die Anpassung der einzelnen Verarbeitungsschritte der Visualisierungspipeline benötigt, angefangen bei effizienter Datenrepräsentation bis hin zu hardware-beschleunigtem Rendering auf der Client-Seite. Diese Doktorarbeit befasst sich zunächst mit verwandten Arbeiten auf dem Gebiet der Remote-Visualisierung mit besonderem Fokus auf interaktiver web-basierter Visualisierung und präsentiert danach Techniken für die interaktive Visualisierung im Browser mit Hilfe moderner Web-Standards wie WebGL und HTML5. Diese Techniken ermöglichen die Visualisierung dynamischer molekularer Datensätze mit mehr als einer Million Atomen bei interaktiven Frameraten durch die Verwendung GPU-basierten Raycastings. Aufgrund der Einschränkungen, welche in einer Browser-basierten Umgebung vorliegen, musste die konkrete Implementierung des GPU-basierten Raycastings angepasst werden. Die Evaluation der daraus resultierenden Performanz zeigt, dass GPU-basierte Techniken das interaktive Rendering von großen Datensätzen ermöglichen und eine im Vergleich zu Polygon-basierten Techniken höhere Bildqualität erreichen. Zur Verringerung der Übertragungszeiten, Reduktion der Latenz und Verbesserung der Darstellungsgeschwindigkeit werden effiziente Ansätze zur Datenrepräsentation und übertragung verwendet. Des Weiteren wird in dieser Doktorarbeit eine GPU-basierte Volumen-Ray-Marching-Technik auf Basis von WebGL 2.0 eingeführt, welche progressive blockweise Datenübertragung verwendet, sowie verschiedene Detailgrade, um ein interaktives Volumenrendering von auf dem Server gespeicherten Datensätzen zu erreichen. Die in dieser Doktorarbeit präsentierten Konzepte und Resultate tragen zur weiteren Verbreitung von interaktiver web-basierter Visualisierung bei. Die erzielten algorithmischen und technologischen Fortschritte bilden eine Grundlage für weiterführende Entwicklungen von interaktiven Visualisierungsanwendungen auf Browser-Basis. Gleichzeitig hat dieser Ansatz das Potential, zukünftig kollaborative Visualisierung in der Cloud zu ermöglichen

Browsing and Experiencing Repositories of Spatially Oriented Historic Photographic Images

Many institutions archive historical images of architecture in urban areas and make them available to scholars and the general public through online platforms. Users can explore these often huge repositories by faceted browsing or keyword-based searching. Metadata that enable these kinds of investigations, however, are often incomplete, imprecise, or even wrong. Thus, retrieving images of interest can be a cumbersome task for users such as art and architectural historians trying to answer their research questions. Many of these images, often containing historic buildings and landscapes, can be oriented spatially using automatic methods such as “structure from motion” (SfM). Providing spatially and temporally oriented images of urban architecture, in combination with advanced searching and exploration techniques, offers new potential in supporting historians in their research. We are developing a 3D web environment useful to historians enabling them to search and access historic photographic images in a spatial context. Related projects use 2D maps, showing only a planar view of the current urban situation. In this paper, we present an approach to create interactive views of 4D city models, i.e., 3D spatial models that show changes over time, to provide a better understanding of the urban building situation regarding the photographer’s position and surroundings. A major feature of the application is to make it possible to spatially align 3D reconstruction models to photogrammetric digitized models based on historical photographs. At the same time, this mixed methods approach is used for validation of the 3D reconstructions

Adaptivity of 3D web content in web-based virtual museums : a quality of service and quality of experience perspective

The 3D Web emerged as an agglomeration of technologies that brought the third dimension to the World Wide Web. Its forms spanned from being systems with limited 3D capabilities to complete and complex Web-Based Virtual Worlds. The advent of the 3D Web provided great opportunities to museums by giving them an innovative medium to disseminate collections' information and associated interpretations in the form of digital artefacts, and virtual reconstructions thus leading to a new revolutionary way in cultural heritage curation, preservation and dissemination thereby reaching a wider audience. This audience consumes 3D Web material on a myriad of devices (mobile devices, tablets and personal computers) and network regimes (WiFi, 4G, 3G, etc.). Choreographing and presenting 3D Web components across all these heterogeneous platforms and network regimes present a significant challenge yet to overcome. The challenge is to achieve a good user Quality of Experience (QoE) across all these platforms. This means that different levels of fidelity of media may be appropriate. Therefore, servers hosting those media types need to adapt to the capabilities of a wide range of networks and devices. To achieve this, the research contributes the design and implementation of Hannibal, an adaptive QoS & QoE-aware engine that allows Web-Based Virtual Museums to deliver the best possible user experience across those platforms. In order to ensure effective adaptivity of 3D content, this research furthers the understanding of the 3D web in terms of Quality of Service (QoS) through empirical investigations studying how 3D Web components perform and what are their bottlenecks and in terms of QoE studying the subjective perception of fidelity of 3D Digital Heritage artefacts. Results of these experiments lead to the design and implementation of Hannibal

Multi feature-rich synthetic colour to improve human visual perception of point clouds

Although point features have shown their usefulness in classification with Machine Learning, point cloud visualization enhancement methods focus mainly on lighting. The visualization of point features helps to improve the perception of the 3D environment. This paper proposes Multi Feature-Rich Synthetic Colour (MFRSC) as an alternative non-photorealistic colour approach of natural-coloured point clouds. The method is based on the selection of nine features (reflectance, return number, inclination, depth, height, point density, linearity, planarity, and scattering) associated with five human perception descriptors (edges, texture, shape, size, depth, orientation). The features are reduced to fit the RGB display channels. All feature permutations are analysed according to colour distance with the natural-coloured point cloud and Image Quality Assessment. As a result, the selected feature permutations allow a clear visualization of the scene's rendering objects, highlighting edges, planes, and volumetric objects. MFRSC effectively replaces natural colour, even with less distorted visualization according to BRISQUE, NIQUE and PIQE. In addition, the assignment of features in RGB channels enables the use of MFRSC in software that does not support colorization based on point attributes (most commercially available software). MFRSC can be combined with other non-photorealistic techniques such as Eye-Dome Lighting or Ambient Occlusion.Xunta de Galicia | Ref. ED481B-2019-061Xunta de Galicia | Ref. ED431F 2022/08Agencia Estatal de Investigación | Ref. PID2019-105221RB-C43Universidade de Vigo/CISU

A heterogeneous data-based proposal for procedural 3D cities visualization and generalization

Ce projet de thèse est né d'un projet de collaboration entre l'équipe de recherche VORTEX/ Objets visuels: de la réalité à l'expression (maintenant REVA: Réel Expression Vie Artificielle) à l'IRIT : Institut de Recherche en Informatique de Toulouse d'une part et de professionnels de l'éducation, entreprises et entités publiques d'autre part. Le projet de collaboration SCOLA est essentiellement une plate-forme d'apprentissage en ligne basée sur l'utilisation des jeux sérieux dans les écoles. Il aide les utilisateurs à acquérir et à repérer des compétences prédéfinies. Cette plate-forme offre aux enseignants un nouvel outil flexible qui crée des scénarios liés à la pédagogie et personnalise les dossiers des élèves. Plusieurs contributions ont été attribuées à l'IRIT. L'une d'elles consiste à suggérer une solution pour la création automatique d'environnements 3D, à intégrer au scénario du jeu. Cette solution vise à empêcher les infographistes 3D de modéliser manuellement des environnements 3D détaillés et volumineux, ce qui peut être très coûteux et prendre beaucoup de temps. Diverses applications et prototypes ont été développés pour permettre à l'utilisateur de généraliser et de visualiser son propre monde virtuel principalement à partir d'un ensemble de règles. Par conséquent, il n'existe pas de schéma de représentation unique dans le monde virtuel en raison de l'hétérogénéité et de la diversité de la conception de contenus 3D, en particulier des modèles de ville. Cette contrainte nous a amené à nous appuyer largement dans notre projet sur de vraies données urbaines 3D au lieu de données personnalisées prédéfinies par le concepteur de jeu. Les progrès réalisés en infographie, les capacités de calcul élevées et les technologies Web ont largement révolutionné les techniques de reconstruction et de visualisation des données. Ces techniques sont appliquées dans divers domaines, en commençant par les jeux vidéo, les simulations et en terminant par les films qui utilisent des espaces générés de manière procédurale et des animations de personnages. Bien que les jeux informatiques modernes n'aient pas les mêmes restrictions matérielles et de mémoire que les anciens jeux, la génération procédurale est fréquemment utilisée pour créer des jeux, des cartes, des niveaux, des personnages ou d'autres facettes aléatoires uniques sur chaque jeu. Actuellement, la tendance est déplacée vers les SIG: Systèmes d'Information Géographiques pour créer des mondes urbains, en particulier après leur mise en œuvre réussie dans le monde entier afin de prendre en charge de nombreuses domaines d'applications. Les SIG sont plus particulièrement dédiés à des applications telles que la simulation, la gestion des catastrophes et la planification urbaine, avec une grande utilisation plus ou moins limitée dans les jeux, par exemple le jeu "Minecraft", dont la dernière version propose une cartographie utilisant des villes du monde réel Geodata in Minecraft. L'utilisation des données urbaines existantes devient de plus en plus répandue dans les applications cartographiques pour deux raisons principales: premièrement, elle permet de comprendre le contenu spatial d'objets urbains de manière plus logique et, deuxièmement, elle fournit une plate-forme commune pour intégrer des informations au niveau de la ville provenant de différents environnements ou ressources et les rendre accessibles aux utilisateurs. Un modèle de ville virtuelle en 3D est une représentation numérique de l'espace urbain qui décrit les propriétés géométriques, topologiques, sémantiques et d'apparence de ses composants. En général, un MV3D\footnote{Modèle de Ville en 3D} sert de plate-forme d'intégration pour plusieurs facettes d'un espace d'informations urbain, comme l'a souligné "Batty": "En bref, les nouveaux modèles ne sont pas simplement la géométrie numérique des modèles traditionnels, mais des bases de données à grande échelle pouvant être visualisées en 3D. En tant que tels, ils représentent déjà un moyen de fusionner des données symboliques ou thématiques plus abstraites, même des modèles symboliques, dans ce mode de représentation".This thesis project was born from a collaborative project between the research team VORTEX / Visual objects: from reality to expression (now REVA: Real Expression Artificial Life) at IRIT: Institute of Research in Computer Science Toulouse on the one hand and education professionals, companies and public entities on the other.The SCOLA collaborative project is essentially an online learning platform based on the use of serious games in schools. It helps users to acquire and track predefined skills. This platform provides teachers with a new flexible tool that creates pedagogical scenarios and personalizes student records. Several contributions have been attributed to IRIT. One of these is to suggest a solution for the automatic creation of 3D environments, to integrate into the game scenario. This solution aims to prevent 3D graphic designers from manually modeling detailed and large 3D environments, which can be very expensive and take a lot of time. Various applications and prototypes have been developed to allow the user to generalize and visualize their own virtual world primarily from a set of rules. Therefore, there is no single representation scheme in the virtual world due to the heterogeneity and diversity of 3D content design, especially city models. This constraint has led us to rely heavily on our project on real 3D urban data instead of custom data predefined by the game designer. Advances in computer graphics, high computing capabilities, and Web technologies have revolutionized data reconstruction and visualization techniques. These techniques are applied in a variety of areas, starting with video games, simulations, and ending with movies that use procedurally generated spaces and character animations. Although modern computer games do not have the same hardware and memory restrictions as older games, procedural generation is frequently used to create unique games, cards, levels, characters, or other random facets on each. Currently, the trend is shifting towards GIS : Geographical Information Systems to create urban worlds, especially after their successful implementation around the world to support many areas of applications. GIS are more specifically dedicated to applications such as simulation, disaster management and urban planning, with a great use more or less limited in games, for example the game "Minecraft", the latest version offers a map using real world cities Geodata in Minecraft. The use of existing urban data is becoming more and more widespread in cartographic applications for two main reasons: first, it makes it possible to understand the spatial content of urban objects in a more logical way and, secondly, it provides a common platform to integrate city-level information from different environments or resources and make them available to users. A 3D virtual city model is a digital representation of urban space that describes the geometric, topological, semantic, and appearance properties of its components. In general, an MV3D: 3D City Model serves as an integration platform for many facets of an urban information space, as "Batty" pointed out: "In short, the new models are not just the digital geometry of traditional models, but large-scale databases that can be visualized in 3D. As such, they already represent a way to merge more abstract symbolic or thematic data, even symbolic patterns, into this mode of representation"

Management and Visualisation of Non-linear History of Polygonal 3D Models

The research presented in this thesis concerns the problems of maintenance and revision control of large-scale three dimensional (3D) models over the Internet. As the models grow in size and the authoring tools grow in complexity, standard approaches to collaborative asset development become impractical. The prevalent paradigm of sharing files on a file system poses serious risks with regards, but not limited to, ensuring consistency and concurrency of multi-user 3D editing. Although modifications might be tracked manually using naming conventions or automatically in a version control system (VCS), understanding the provenance of a large 3D dataset is hard due to revision metadata not being associated with the underlying scene structures. Some tools and protocols enable seamless synchronisation of file and directory changes in remote locations. However, the existing web-based technologies are not yet fully exploiting the modern design patters for access to and management of alternative shared resources online. Therefore, four distinct but highly interconnected conceptual tools are explored. The first is the organisation of 3D assets within recent document-oriented No Structured Query Language (NoSQL) databases. These "schemaless" databases, unlike their relational counterparts, do not represent data in rigid table structures. Instead, they rely on polymorphic documents composed of key-value pairs that are much better suited to the diverse nature of 3D assets. Hence, a domain-specific non-linear revision control system 3D Repo is built around a NoSQL database to enable asynchronous editing similar to traditional VCSs. The second concept is that of visual 3D differencing and merging. The accompanying 3D Diff tool supports interactive conflict resolution at the level of scene graph nodes that are de facto the delta changes stored in the repository. The third is the utilisation of HyperText Transfer Protocol (HTTP) for the purposes of 3D data management. The XML3DRepo daemon application exposes the contents of the repository and the version control logic in a Representational State Transfer (REST) style of architecture. At the same time, it manifests the effects of various 3D encoding strategies on the file sizes and download times in modern web browsers. The fourth and final concept is the reverse-engineering of an editing history. Even if the models are being version controlled, the extracted provenance is limited to additions, deletions and modifications. The 3D Timeline tool, therefore, implies a plausible history of common modelling operations such as duplications, transformations, etc. Given a collection of 3D models, it estimates a part-based correspondence and visualises it in a temporal flow. The prototype tools developed as part of the research were evaluated in pilot user studies that suggest they are usable by the end users and well suited to their respective tasks. Together, the results constitute a novel framework that demonstrates the feasibility of a domain-specific 3D version control