An approach for facilitating service management in networked virtual manufacturing environments

This paper defines an approach for management of networked entities, including either hardware devices or software services. In describing this approach, the paper presents a model architecture that is intended for, but not limited to, virtual environments. A sample application for dynamically monitoring and controlling remote facilities illustrates the benefits of this approach to virtual manufacturing. The service interface has functionality that enables a client to download its graphical representation and behaviors for display within a client application's virtual environment.     

A Flexible Architecture for Virtual Humans in Networked Collaborative Virtual Environments

Complex virtual human representation provides more natural interaction and communication among participants in networked virtual environments, hence it is expected to increase the sense of being together within the same virtual world. We present a flexible framework for the integration of virtual humans in networked collaborative virtual environments. A modular architecture allows flexible representation and control of the virtual humans, whether they are controlled by a physical user using all sorts of tracking and other devices, or by an intelligent control program turning them into autonomous actors. The modularity of the system allows for fairly easy extensions and integration with new techniques making it interesting also as a testbed for various domains from “classic” VR to psychological experiments. We present results in terms of functionalities, example applications and measurements of performance and network traffic with an increasing number of participants in the simulation.     

Automatic speech grammar generation during conceptual modelling of virtual environments

Speech interfaces are becoming more and more popular as a means to interact with virtual environments but the development and integration of these interfaces is usually still ad hoc, especially the speech grammar creation of the speech interface is a process commonly performed by hand. In this paper, we introduce an approach to automatically generate a speech grammar which is generated using semantic information. The semantic information is represented through ontologies and gathered from the conceptual modelling phase of the virtual environment application. The utterances of the user will be resolved using queries onto these ontologies such that the meaning of the utterance can be resolved. For validation purposes we augmented a city park designer with our approach. Informal tests validate our approach, because they reveal that users mainly use words represented in the semantic data, and therefore also words which are incorporated in the automatically generated speech grammar.

Social interaction regulation in virtual web environments using the Social Theatres model

At the present time virtual communities are overspread in the web, providing users a cyber-place to share common purposes and interact with other users around the world. Interaction in these environments grapple with new challenges concerning to provide their users better tools to interact and fulfil their goals. In this context we propose a model to create regulated interaction environments based on the theatre metaphor: the Social Theatres. A dynamic multi-layer software architecture (ASTeaS) was developed to support this web-based interaction model, allowing easy construction of such social interaction spaces and adaptation to users' devices requirements. In this paper we discuss the usage of interaction regulation in virtual environments supported by the Social Theatres model and evaluate some aspects of the users interaction in two different case study scenarios.     

网格环境下基于服务的分布式查询处理机制研究

OGSA-DQP是一种用于网格环境、基于服务的分布式查询处理系统,实现了运行在不同平台的分布式数据密集型应用的高级数据访问与集成服务方法,为用户提供一致的虚拟关系数据视图和分布式数据查询支持。文章描述了其体系结构、分析了其查询和优化机制,并在不同条件下测试了查询性能,为寻找系统查询性能瓶颈、提高系统查询响应时间提供依据。     

一个可扩展的分布式虚拟环境体系架构

分布式虚拟环境的可扩展性包括规模扩展性和系统扩展性两方面的内容.综合Plug-in机制和进程级别的场景分区管理技术,从通信结构、兴趣管理、一致性管理和数据复制这几个方面综合考虑,提出了一个满足规模扩展性和系统扩展性的分布式虚拟环境体系结构,并介绍了具体应用实例.     

Influence of contextual objects on spatial interactions and viewpoints sharing in virtual environments

Collaborative virtual environments (CVEs) are 3D spaces in which users share virtual objects, communicate, and work together. To collaborate efficiently, users must develop a common representation of their shared virtual space. In this work, we investigated spatial communication in virtual environments. In order to perform an object co-manipulation task, the users must be able to communicate and exchange spatial information, such as object position, in a virtual environment. We conducted an experiment in which we manipulated the contents of the shared virtual space to understand how users verbally construct a common spatial representation of their environment. Forty-four students participated in the experiment to assess the influence of contextual objects on spatial communication and sharing of viewpoints. The participants were asked to perform in dyads an object co-manipulation task. The results show that the presence of a contextual object such as fixed and lateralized visual landmarks in the virtual environment positively influences the way male operators collaborate to perform this task. These results allow us to provide some design recommendations for CVEs for object manipulation tasks.     

An end-to-end communication architecture for collaborative virtual environments

Synchronous collaboration in virtual reality spaces has specific requirements that differ from those of other application data, leading to a different communication approach. Update messages corresponding to the change in the state of a shared object must be communicated both reliably and in a timely manner among users. While a lot of research has been done in terms of transmission of update messages representing the motion of avatars and objects, very few works focus on collaboration itself. Here, we present an architecture that supports tightly coupled collaborative tasks to be performed efficiently in virtual environments. The architecture consists of an application-general layer which is mapped into a communication protocol. An implementation is also presented as proof of concept.     

A visual language for modeling and executing traceability queries

Current software and systems engineering tools provide only basic trace features, and as a result users are often compelled to construct non-trivial traceability queries using generic query languages such as SQL. In this paper, we present an alternative approach which defines traceability strategies for a project using UML class diagrams and then constructs trace queries as constraints upon subsets of the model. The visual trace modeling language (VTML) allows users to model a broad range of trace queries while hiding underlying technical details and data structures. The viability and expressiveness of VTML for use in a real project are demonstrated through modeling a broadly representative set of queries for a web-based health-care system. It is then evaluated through an experiment with human users to assess the readability and writability of VTML queries in comparison to generic SQL queries. We found that users read and constructed traceability queries considerably faster using VTML than using SQL. Furthermore, visually constructed traceability queries were substantially more correct compared to the same queries constructed with SQL.     

Exploring Correlated Subspaces for Efficient Query Processing in Sparse Databases

Sparse data are becoming increasingly common and available in many real-life applications. However, relatively little attention has been paid to effectively model the sparse data and existing approaches such as the conventional "horizontal” and "vertical” representations fail to provide satisfactory performance for both storage and query processing, as such approaches are too rigid and generally do not consider the dimension correlations. In this paper, we propose a new approach, named HoVer, to store and conduct query for sparse data sets in an unmodified RDBMS, where HoVer stands for Horizontal representation over Vertically partitioned subspaces. According to the dimension correlations of sparse data sets, a novel mechanism has been developed to vertically partition a high-dimensional sparse data set into multiple lower-dimensional subspaces, and all the dimensions are highly correlated intrasubspace and highly unrelated intersubspace, respectively. Therefore, original data objects can be represented by the horizontal format in respective subspaces. With the novel HoVer representation, users can write SQL queries over the original horizontal view, which can be easily rewritten into queries over the subspace tables. Experiments over synthetic and real-life data sets show that our approach is effective in finding correlated subspaces and yields superior performance for the storage and query of sparse data.     

The frequent wayfinding-sequence (FWS) methodology: Finding preferred routes in complex virtual environments

Advances in computing techniques, as well as the reduction in the cost of technology, have made possible the viability and spread of complex virtual environments (VEs). However, efficient navigation within these environments remains problematic for the user. Several research projects have shown that users of VEs are often disoriented and have extreme difficulty completing navigational tasks. Furthermore, there is often more than one route to get to a specified destination. Novice users often lack the spatial knowledge needed to pick an appropriate route due to the deficiency of experience with the system. A number of navigation tools such as maps, 3-D thumbnails, trails, and personal agents have been proposed. The introduction of these tools have met with some degree of success, but most researchers agree that new techniques need to be developed to aid users efficiently navigate within complex VEs. In this paper, we propose the frequent wayfinding-sequence (FWS) methodology that uses a modified sequence mining technique to discover a model of routes taken by experienced users of a VE. The model is used to build an interface that provides navigation assistance to novice users by recommending routes. We conducted both real world and simulation experiments using our methodology. Results from the real world experiment suggest that the FWS approach has the potential to improve the user's navigation performance and the quality of the human-computer interaction. Our simulation studies showed that our approach is scalable, efficient, and able to find useful route models for complex VEs.     

VR-VIBE: A Virtual Environment for Co-operative Information Retrieval

We present a virtual reality application called VR-VIBE which is intended to support the co-operative browsing and filtering of large document stores. VR-VIBE extends a visualisation approach proposed in a previous two dimensional system called VIBE into three dimensions, allowing more information to be visualised at one time and supporting more powerful styles of interaction, The essence of VR-VIBE is that multiple users can explore the results of applying several simultaneous queries to a corpus of documents. By arranging the queries into a spatial framework, the system shows the relative attraction of each document to each query by its spatial position and also shows the absolute relevance of each document to all of the queries. Users may then navigate the space, select individual documents, control the display according to a dynamic relevance threshold and dynamically drag the queries to new positions to see the effect on the document space. Co-operative browsing is supported by directly embodying users and providing them with the ability to interact over live audio connections and to attach brief textual annotations to individual documents. Finally, we conclude with some initial observations gleaned from our experience of constructing VR-VIBE and using it in the laboratory setting.     

Graphical presentation of boolean expressions in a database query language: design notes and an ergonomic evaluation

A new query language designed to improve ease-of-use and ease-of-learning for 'naive' users is presented. Its main interest is to avoid the explicit use of boolean operators for set operations by pointing on Venn diagrams. A human factors comparison with a more traditional design has been performed, using a query writing task. Results show that graphic representation of selected subsets allows less error-prone queries in a single relation database.     

Badumna: A decentralised network engine for virtual environments

Many of today’s virtual environment applications, such as massively multiplayer online games, involve a large and rapidly changing set of users. The server-based architecture of these applications makes its hard for them to support the dynamic user base and provide a scalable solution. Badumna, a scalable network engine for large-scale virtual environments, was developed to address these issues. The approach is based on a decentralised architecture using a structured peer-to-peer network. In order to ensure a highly scalable and efficient design, Badumna uses techniques that include neighbour introductions and the formation of dynamic bounded regions to reduce the load on the peer-to-peer network. The performance of Badumna is evaluated using extensive simulations. Results indicate that Badumna is able to scale to a large number of users without placing any additional overheads on the network that degrade performance.     

The H-N2N framework: towards providing interperception in massive applications

We propose a framework with a flexible architecture that have been designed and implemented for collaborative interaction of users, to be applied in massive applications through the Web. We introduce the concept of interperception and use technologies as massive virtual environments and teleoperation for the creation of environments (mixing virtual and real ones) in order to promote accessibility and transparency in the interaction between people, and between people and animate devices (such as robots) through the Web. Experiments with massive games, with interactive applications in digital television, with users and robots interacting in virtual and real versions of museums and cultural centers are presented to validate our proposal.     

Realization of reconfigurable virtual environments for virtual testing

1 Introduction The scalability of virtual environments (VEs) that allow users to change and modify their contents and context depending on application requirements has been a de facto feature of virtual reality technology. Engineering uses such as virtual testing and exper- imenting applications demand VEs to be highly or fully reconfigurable. In reality, however, satisfactory reconfiguration of a virtual environment is yet to be achieved, due to the high accuracy of spatial data in- put and…     

A paradigm for controlling virtual humans in urban environment simulations

This paper presents a new architecture for simulating virtual humans in complex urban environments. The approach is based on the integration of six modules. Four key modules are used in order to manage environmental data, simulate human crowds, control interactions between virtual humans and objects, and generate tasks based on a rule-based behavioral model. The communication between these modules is made through a client/server system. Finally, all low-level virtual human actions are delegated to a single motion and behavioral control module. Our architecture combines various human and object simulation aspects, based on the coherent extraction and classification of information froma virtual city database. This architecture is discussed in this paper, together with a detailed case study example.     

Inference-based procedural modeling of solids

As virtual environments become larger and more complex, there is an increasing need for more automated construction algorithms to support the development process. We present an approach for modeling solids by combining prior examples with a simple sketch. Our algorithm uses an inference-based approach to incrementally fit patches together in a consistent fashion to define the boundary of an object. This algorithm samples and extracts surface patches from input models, and develops a Petri net structure that describes the relationship between patches along an imposed parameterization. Then, given a new parameterized line or curve, we use the Petri net to logically fit patches together in a manner consistent with the input model. This allows us to easily construct objects of varying sizes and configurations using arbitrary articulation, repetition, and interchanging of parts. The result of our process is a solid model representation of the constructed object that can be integrated into a simulation-based environment.     

Hybrid inverse motion control for virtual characters interacting with sound synthesis Application to percussion motion

The ever growing use of virtual environments requires more and more engaging elements for enhancing user experiences. Specifically regarding sounding virtual environments, one promising option to achieve such realism and interactivity requirements is the use of virtual characters interacting with sounding objects. In this paper, we focus as a case study on virtual characters playing virtual music instruments. We address more specially the real-time motion control and interaction of virtual characters with their sounding environment for proposing engaging and compelling virtual music performances. Combining physics-based simulation with motion data is a recent approach to finely represent and modulate this motion-sound interaction, while keeping the realism and expressivity of the original captured motion. We propose a physically-enabled environment in which a virtual percussionist interacts with a physics-based sound synthesis algorithm. We introduce and extensively evaluate the Hybrid Inverse Motion Control (HIMC), a motion-driven hybrid control scheme dedicated to the synthesis of upper-body percussion movements. We also propose a physics-based sound synthesis model with which the virtual character can interact. Finally, we present an architecture offering an effective way to manage heterogenous data (motion and sound parameters) and feedback (visual and sound) that influence the resulting virtual percussion performances.     

Parallel query processing with zigzag trees

In this article, we describe our approach to the compile-time optimization and parallelization of queries for execution in DBS3 or EDS. DBS3 is a shared-memory parallel database system, while the EDS system has a distributed-memory architecture. Because DBS3 implements a parallel dataflow execution model, this approach applies to both architectures. Using randomized search strategies enables the exploration of a search space large enough to include zigzag trees, which are intermediate between left-deep and right-deep trees. Zigzag trees are shown to provide better response time than right-deep trees in case of limited memory. Performance measurements obtained using the DBS3 prototype show the advantages of zigzag trees under various conditions.