Animated visualization of spatial–temporal trajectory data for air-traffic analysis

Virtual 3D city models are essential visualization tools for effective communication of complex urban spatial information. Immersive visualization of virtual 3D city models offers an intuitive access to and an effective way of realization of urban spatial information, enabling new collaborative applications and decision-support systems. This paper discusses techniques for and usage of fully immersive environments for visualizing virtual 3D city models by advanced 3D rendering techniques. Fully immersive environments imply a number of specific requirements for both hardware and software, which are discussed in detail. Further, we identify and outline conceptual and technical challenges as well as possible solution approaches by visualization system prototypes for large-scale, fully immersive environments. We evaluate the presented concepts using two application examples and discuss the results.

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. 
\n3D 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. 
\nIn 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.
\nDigital 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. 
\n3D 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.
\nAs 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.
\nOpenStreetMap 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.
\nResults 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.
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3D multi-user virtual environments (MUVE) bring new opportunities to foreign language teaching and learning as a platform for teaching practices. Due to immersive and interactive nature of 3D MUVE, these tools have gained popularity in the field of foreign language learning and teaching. The power of virtual learning environments lies in creating immersive 3-D spaces that give users a sense of learning by doing. Moreover, the environment is interactive and is much the same as real world interaction. MUVE provides strong support for synchronous collaborations, interactions, and immersive environments for experiential and constructivist learning settings. Some key features of the virtual worlds comprise the ability to construct 3D environments that simulate real world situations, as well as the ability to have a virtual identity to create a cross-cultural self and the ability to have participants from around the world acting virtually in designated roles that convey new types of learning within this environment.

Abstract. Virtual 3D city models are integrated complex compositions of spatial data of different themes, origin, quality, scale, and dimensions. Within this paper, we address the problem of spatial compatibility of geodata aiming to provide support for ad-hoc integration of virtual 3D city models including geodata of different sources and themes like buildings, terrain, and city furniture. In contrast to related work which is dealing with the integration of redundant geodata structured according to different data models and ontologies, we focus on the integration of complex 3D models of the same representation (here: CityGML) but regarding to the geometric-topological consistent matching of non-homologous objects, e.g. a building is connected to a road, and their geometric homogenisation. Therefore, we present an approach including a data model for a Geodata Join and the general concept of an integration procedure using the join information. The Geodata Join aims to bridge the lack of information between fragmented geodata by describing the relationship between adjacent objects from different datasets. The join information includes the geometrical representation of those parts of an object, which have a specific/known topological or geometrical relationship to another object. This part is referred to as a Connector and is either described by points, lines, or surfaces of the existing object geometry or by additional join geometry. In addition, the join information includes the specification of the connected object in the other dataset and the description of the topological and geometrical relationship between both objects, which is used to aid the matching process. Furthermore, the Geodata Join contains object-related information like accuracy values and restrictions of movement and deformation which are used to optimize the integration process. Based on these parameters, a functional model including a matching algorithm, transformation methods, and conditioned adjustment methods can be established in order to facilitate ad-hoc 3D homogenisation for consistent 3D city models.

Connecting users to virtual worlds within MPEG-V standardization

Three-dimensional (3D) virtual environments bring people together in real time irrespective of their geographical location to facilitate collaborative learning and working together in an engaging and fulfilling way. However, it can be difficult to amass suitable data to gauge how well students perform in these environments. With this in mind, the current study proposes a methodology for monitoring students’ learning experiences in 3D virtual worlds (VWs). It integrates a computer-based mechanism that mixes software agents with natural agents (users) in conjunction with a fuzzy logic model to reveal evidence of learning in collaborative pursuits to replicate the sort of observation that would normally be made in a conventional classroom setting. Software agents are used to infer the extent of interaction based on the number of clicks, the actions of users, and other events. Meanwhile, natural agents are employed in order to evaluate the students and the way in which they perform. This is beneficial because such an approach offers an effective method for assessing learning activities in 3D virtual environments.

As a frontier research topic in the field of scientific visualization, trajectory data visualization extracts valuable patterns and knowledge from trajectory data for decision support via spatiotemporal trajectory visualization techniques. We propose the concept of multivariate trajectory data and interpret two categories of attributes that are based on geographical space and abstract space. Properly analyzing multivariate trajectory data depends on many factors such as visualization task and data sparsity. Therefore, we generalize rich interactions to explore the evolution of trajectory events and transform the issue into a more intelligibly perceptual task, which derives our discussion regarding advantages and limitations of the analytical methods. This review endeavors to provide a quick and thorough cognition and comprehension with regard to fundamental features and numerous outcomes in visual analytics for trajectory data, seeks to promote comparisons and criticisms about the descriptive framework for multivariate spatiotemporal trajectory data visualization, and aims to encourage the exploration of emerging methods and techniques.

As an important task in spatial data mining, trajectory transportation mode recognition can reflect various individual behaviors and traveling patterns in urban space. As trajectory is essentially a sequence, many scholars use the sequence inference models to mine the information in trajectory data. However, such methods often ignored the spatial correlation between trajectory points and implemented the evaluation based only on representative feature statistics selected in the trajectory data preprocessing stage, thus have difficulties in acquiring high-order traveling pattern features. In this study, we propose a novel ensemble recognition method for representing trajectory data with the graph structure based on sequence and dependency relations. This method integrates the sequence of trajectory points and the correlation between characteristic points of a travel path into a fused graph convolutional network to obtain semantic feature information at multiple levels. We validate our proposed method with experiments on the trajectory benchmark dataset from the Microsoft GeoLife project. The results demonstrated that our proposed graph network outperforms other baseline methods in the transportation mode recognition task of trajectories. This method can help to discover the movement patterns of urban residents, and further provide effective assistance for the management of cities.

This paper presents an approach to visualize and analyze 3D building information models within virtual 3D city models. Building information models (BIMs) formalize and represent detailed information related to the lifecycle of buildings, e.g., information about composition, facilities, equipment, usage, maintenance, and workflows such as rescue scenarios. Complementary, virtual 3D city models represent objects and phenomena of urban areas, typically at a lower level of information detail; virtual 3D city models as a general framework and platform for spatial data allow us to seamlessly combine GIS and BIM data. In our approach, BIM data and 3D geodata, both provided by possibly distributed, heterogeneous web services, are efficiently integrated by the underlying real-time 3D geovisualization system. To facilitate insights into complex spatial scenarios, two configurable BIM-specific visualization techniques have been developed, which map BIM data onto 3D building graphics variables respectively geometrically distort 3D building representations. The visualization functionality can itself be accessed as a specialized web 3D perspective view service. We demonstrate our approach by a fire and rescue scenario for a part of a 3D campus model.

There is increased interest in, and accelerating technological development of, internet-based persistent three-dimensional (3D) virtual environments. The applications of these `virtual worlds' are growing in the fields of entertainment and information assimilation such as virtual real estate, brand building, and marketing. Such applications could, in time, lead to serious economic and business transformation. However, there is a lack of empirical work examining differences between virtual worlds and traditional virtual channels such as websites, and suggesting effective entry strategies for organizations that seek to leverage their presence in virtual worlds. This paper attempts to provide a starting point for such a discussion. Results from our qualitative and quantitative analysis indicate that there is a significant difference in perceptions of trust, product diagnosticity, informativeness, and product descriptions between websites and virtual worlds. Results also suggest that organizations need to employ a synergy strategy when marketing experience goods in virtual worlds.

Nowadays e-commerce websites offer users such a huge amount of products, which far from facilitating the buying process, actually make it more difficult. Hence, recommenders, which learn from users' preferences, are consolidating as valuable instruments to enhance the buying process in the 2D Web. Indeed, 3D virtual environments are an alternative interface for recommenders. They provide the user with an immersive 3D social experience, enabling a richer visualisation and increasing the interaction possibilities with other users and with the recommender. In this paper, we focus on a novel framework to tightly integrate interactive recommendation systems in a 3D virtual environment. Additionally, we evaluate the framework based on several usability criteria. Results demonstrate that users positively valued the experience.

Los entornos virtuales 3D son sistemas tecnológicos avanzados, con múltiples potencialidades en el proceso de enseñanza-aprendizaje.En los últimos años diferentes instituciones han impulsado la necesaria adquisición de una serie de competencias clave para el siglo XXI tales como la iniciativa, el trabajo en equipo, la creatividad, la flexibilidad o la competencia digital. Los entornos virtuales multiusuario o espacios de simulación 3D son sistemas inmersivos, interactivos, personalizables, accesibles y programables, que permiten diseñar actividades complejas de carácter educativo dando respuesta a estas competencias clave. Para ello resulta necesario establecer una adecuada estrategia didáctica que permita poner en acción conocimientos y habilidades, y diseñar adecuados mecanismos de registro y sistematización.En el presente artículo se exponen las potencialidades de estos entornos y se presentan dos experiencias realizadas en estos espacios 3D: (1) para el desarrollo de la competencia de trabajo en equipo y autogestión, y (2) para la evaluación de la competencia digital en futuros maestros.

Ambient Intelligence (AmI) has historically addressed the interaction of people with computer controlled physical worlds. More recently, there has been interest in their virtual counterparts, such as SecondLife in which humanoid avatars interact with each other and their worlds in ways that are analogous to our relationship with the physical world. Virtual and physical worlds can have complex relationships ranging from either each augmenting the other, to the provision of services, such as eLearning. Virtual-Reality extends eLearning environments (eg regular audio, video, and text,) by enabling abstract concepts and entities to be given tangible forms within the virtual world. Also, students and teachers take the form of avatars allowing them to employ avatars to establish their social presence in a wide variety of ways. This paper introduces two popular virtual reality tools, presents a comprehensive review of the literature related to social presence and describes our practical work in progress towards constructing a mixed reality iClassroom.Keywordssocial presencevirtual learning environmentsSecond Life

Virtual 3D city models serve as integration platforms for complex geospatial and georeferenced information and as medium for effective communication of spatial information. In order to explore these information spaces, navigation techniques for controlling the virtual camera are required to facilitate wayfinding and movement. However, navigation is not a trivial task and many available navigation techniques do not support users effectively and efficiently with their respective skills and tasks. In this article, we present an assisting, constrained navigation technique for multiscale virtual 3D city models that is based on three basic principles: users point to navigate, users are lead by suggestions, and the exploitation of semantic, multiscale, hierarchical structurings of city models. The technique particularly supports users with low navigation and virtual camera control skills but is also valuable for experienced users. It supports exploration, search, inspection, and presentation tasks, is easy to learn and use, supports orientation, is efficient, and yields effective view properties. In particular, the technique is suitable for interactive kiosks and mobile devices with a touch display and low computing resources and for use in mobile situations where users only have restricted resources for operating the application. We demonstrate the validity of the proposed navigation technique by presenting an implementation and evaluation results. The implementation is based on service-oriented architectures, standards, and image-based representations and allows exploring massive virtual 3D city models particularly on mobile devices with limited computing resources. Results of a user study comparing the proposed navigation technique with standard techniques suggest that the proposed technique provides the targeted properties, and that it is more advantageous to novice than to expert users.

Despite the fact that virtual worlds and other types of multi-user 3D collaboration spaces have long been subjects of research and of application experiences, it still remains unclear how to best benefit from meeting with colleagues and peers in a virtual environment with the aim of working together. Making use of the potential of virtual embodiment, i.e. being immersed in a space as a personal avatar, allows for innovative new forms of collaboration. In this paper, we present a framework that serves as a systematic formalization of collaboration elements in virtual environments. The framework is based on the semiotic distinctions among pragmatic, semantic and syntactic perspectives. It serves as a blueprint to guide users in designing, implementing, and executing virtual collaboration patterns tailored to their needs. We present two team and two community collaboration pattern examples as a result of the application of the framework: Virtual Meeting, Virtual Design Studio, Spatial Group Configuration, and Virtual Knowledge Fair. In conclusion, we also point out future research directions for this emerging domain.Keywordsgroup interactionpatternsembodied collaborationpresencevirtual worldsMUVECSCWblueprintframework