The Network Architecture and Protocols for Distributed Virtual Environment

In this paper, the properties of distributed virtual environment (DVE) and the requirements on computer networks is briefly reviewed. A multicast protocol, called sender initiated grouping multicast protocol for DVE (SIGMP), is proposed. This new multicast protocol is based on a novel concept, multicast group (MG), which divides all participants in a DVE system into groups, among which there is a multicast group trustee (MGT) node to manage the group. The protocol provides unreliable/reliable, totally ordered and multiple to multiple multicast transmission service for DVE systems without sacrificing the communication efficiency heavily. At the same time, reliable unicast and one to multiple multicast transmission services are also supported. The performance analysis of the new protocols is also presented. Based on SIGMP, a simple demonstration of DVE system is designed and implemented. This demo system is running on several SGI workstations connected by a FDDI and Ethernet network.

Integration of Manufacturing Services into Virtual Environments over the Internet

Virtual reality (VR) is a rapidly developing technology that has a wide spectrum of industrial and commercial applications. Networked (distributed or shared) virtual environments (VE) are of growing interest to modern manufacturing industry; a dominating use of networked virtual manufacturing environments (VMEs) is on-line visualisation and collaborative control of 3D information. This has to be supported by real-time data transfer. To meet a broad range of common requirements for Internet-based VE communications, particularly for virtual manufacturing and collaborative design and control, this paper presents a networked virtual environment system that is designed to support networked virtual design and manufacturing. The system is implemented with manufacturing message specification (MMS) standards so as to integrate a range of manufacturing services into networked VEs over the Internet.

A Mobile Agent-Based Prototype of HeterogeneousDistributed Virtual Environment Systems

Mobile agents provide a new method for the distributed computation. This paper presents the advantages of using mobile agents in a distributed virtual environment (DVE) system, and describes the architecture of heterogeneous computer's distributed virtual environment system (HCWES) designed to populate some mobile agents as well as stationary agents. Finally, the paper introduces how heterogeneous computer network communication is to be realized.

A Distributed LRTCO Algorithm in Large-Scale DVE Multimedia Systems

In the large-scale Distributed Virtual Environment(DVE)multimedia systems,one of key challenges is to distributedly preserve causal order delivery of messages in real time.Most of the existing causal order control approaches with real-time constraints use vector time as causal control information which is closely coupled with system scales.As the scale expands,each message is attached a large amount of control information that introduces too much network transmission overhead to maintain the real-time causal order delivery.In this article,a novel Lightweight Real-Time Causal Order(LRTCO)algorithm is proposed for large-scale DVE multimedia systems.LRTCO predicts and compares the network transmission times of messages so as to select the proper causal control information of which the amount is dynamically adapted to the network latency variations and unconcerned with system scales.The control information in LRTCO is effective to preserve causal order delivery of messages and lightweight to maintain the real-time property of DVE systems.Experimental results demonstrate that LRTCO costs low transmission overhead and communication bandwidth,reduces causal order violations efficiently,and improves the scalability of DVE systems.

Automatic object annotation in streamed and remotely explored large 3D reconstructions

We introduce a novel framework for 3 D scene reconstruction with simultaneous object annotation,using a pre-trained 2 D convolutional neural network(CNN),incremental data streaming,and remote exploration,with a virtual reality setup.It enables versatile integration of any 2 D box detection or segmentation network.We integrate new approaches to(i)asynchronously perform dense 3 D-reconstruction and object annotation at interactive frame rates,(ii)efficiently optimize CNN results in terms of object prediction and spatial accuracy,and(iii)generate computationally-efficient colliders in large triangulated3 D-reconstructions at run-time for 3 D scene interaction.Our method is novel in combining CNNs with long and varying inference time with live 3 D-reconstruction from RGB-D camera input.We further propose a lightweight data structure to store the 3 D-reconstruction data and object annotations to enable fast incremental data transmission for real-time exploration with a remote client,which has not been presented before.Our framework achieves update rates of 22 fps(SSD Mobile Net)and 19 fps(Mask RCNN)for indoor environments up to 800 m^(3).We evaluated the accuracy of 3 D-object detection.Our work provides a versatile foundation for semantic scene understanding of large streamed3 D-reconstructions,while being independent from the CNN’s processing time.Source code is available for non-commercial use.