Kostas Kapetanakis

HTML5 and WebSockets; challenges in network 3D collaboration

The emergence of HTML5 and other associated web technologies have turned browser applications to cross-platform and device independent ones. In particular HTML5, WebSockets and X3Dom can shape a diversity of future applications, where the client-server operations will be obsolete. The X3Dom technology combines JavaScript, HTML5 and X3D to provide 3D graphics visualization and interaction in a web-browser without a plug-in. Enriched with a WebSockets implementation for maintaining a persistent and bidirectional TCP connection with a server, a web application can communicate, stream and transfer events or other data to its clients creating a full collaborative 3D environment. In this paper, we introduce an architecture for interactive 3D scenes streaming over the web. We also demonstrate a collaborative 3D web-application for preschool childrens education that capitalizes on the above technologies. Small classes, real or virtual, can be arranged around an instructor who can control the main 3D scenery. The application can provide a positive and encouraging environment for toddlers to interact with computers while recognizing and playing with 3D animated models of popular animals.

Evaluation of techniques for web 3D graphics animation on portable devices

Providing Internet users with good 3D representations used to be a hard task, not only for web graphic designers but also for web programmers. However, the rapid evolution of SmartPhones has drastically changed the industry. In this paper we attempt to evaluate server and client-side rendering procedures for web 3D animation delivery. Using Ajax and WebSockets, we have developed two discrete instances of a server-side rendering system. We have also implemented an X3Dom equivalent scenario that utilizes X3D and HTML5/WebGL technologies, to emulate client-side rendering on the same environment. The three implementations are evaluated in terms of battery and memory consumption, latency in graphics display and required network resources.

Adaptive video streaming on top of Web3D: A bridging technology between X3DOM and MPEG-DASH

Innovative technologies, implemented in web browsers, have led to the rise of a new era of virtual worlds. Devices with strong hardware installed may now present 3D virtual worlds utilizing user interaction in High Definition (HD) monitors. Recent frameworks such as X3DOM provide a free of plug-ins solution to present interactive 3D graphics and animations within a browser. Furthermore, MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard can be implemented in server-client applications to adapt dynamically the video streaming quality in order to provide the best possible user experience. In this work, we present an approach to extend the adaptation methods of X3DOM by adding a mechanism to perform dynamic adaptation and achieve HD video delivery in 3D Virtual Reality (VR) worlds. We maintain the advantages of both bridged technologies and provide a web-friendly application solution without the requirement of software installation.

Adaptive streaming of complex Web 3D scenes based on the MPEG-DASH standard

Modern Web 3D technologies allow us to display complex interactive 3D content, including models, textures, sounds and animations, using any HTML-enabled web browser. Thus, due to the device-independent nature of HTML5, the same content might have to be displayed on a wide range of different devices and environments. This means that the display of Web 3D content is faced with the same Quality of Experience (QoE) issues as other multimedia types, concerning bandwidth, computational capabilities of the end device, and content quality. In this paper, we present a framework for adaptive streaming of interactive Web 3D scenes to web clients using the MPEG-DASH standard. We offer an analysis of how the standard’s Media Presentation Description schema can be used to describe adaptive Web 3D scenes for streaming, and explore the types of metrics that can be used to maximize the user’s QoE. Then, we present a prototype client we have developed, and demonstrate how the 3D streaming process can take place over such a client. Finally, we discuss how the client framework can be used to design adaptive streaming policies that correspond to real-world scenarios.

iPromotion: A Cloud-Based Platform for Virtual Reality Internet Advertising

We present a large-scale platform for distributing Virtual Reality advertisements over the World Wide Web. The platform aims at receiving and transmitting large amounts of data over mobile and desktop devices in Smart City contexts, is based on a modular and distributed architecture to allow for scalability, and incorporates content-based search capabilities for Virtual Reality (VR) scenes to allow for content management. Data is stored on a cloud repository, to allow for a large amount of VR material to be kept and distributed, and follows a service-based approach of independent subsystems for the management, conversion and streaming of information. In order to function over a wide range of used end-devices, from mobile phones to high-end desktop PCs, the system is based on HTML5 technologies, and implements a remote rendering server to alleviate the computational burden on the end device. Furthermore, an extension of the MPEG-7 standard is used for the description and retrieval of 3D scenes from the cloud, and we have further ensured compliance of our system with a number of other structure and communication standards, to ensure extensibility and reusability of the sub-modules. The platform is a research work in progress: we present the subsystems already implemented, plan our next steps and describe our contributions to research.

Integrating WebRTC and X3DOM: bridging the gap between communications and graphics

In recent years, with the emergence of HTML5, the Web has managed to evolve from an Internet application for information announcement and exchange to a toolkit provided for pervasive, ubiquitous and collaborative services. In this context, the Web can ultimately provide Real-Time Communication (RTC) services between browsers via the Internet. WebRTC is the standardized project that provides browsers and mobile applications with RTC capabilities via simple JavaScript APIs. This opens new horizons in web-based applications such as capabilities for online gaming, support for complicated 3D graphics in real-time, video-conferencing, exchanging of text messages, immersive technology, etc. In this paper, we introduce the integration of WebRTC capabilities within virtual 3D worlds and present several implementations that bridge WebRTC and X3DOM technologies. In the applications we have developed, virtual 3D collaborative environments are provided for the cooperation of web peers at real time, while they are able to manipulate a 3D scene without the use of plugins. In this context, an online educational game and an immersive conference tool supporting all types of real-time communication such as video chat, text messaging and the use of social media, both using WebRTC over X3DOM, are presented and thoroughly discussed.

State-of-the-art web technologies for progressive presentation of synthetic cultural heritage scenes

With the advancement of both 3D scanning technologies and Web3D, it is now feasible to convert Cultural Heritage objects and locations of interest into synthetic 3D scenes, and directly embed them in HTML pages so that users can visit them remotely, from practically any Web-enabled device. However, since such scanned scenes tend to be extremely detailed and consist of large volumes of data, browsing them can become a long, burdensome experience. While a number of progressive streaming approaches for 3D graphics have been proposed in the past, such methods tend to require a radical restructuring of the original data in order to be streamed to a web client. We implement a platform for 3D scenes that can stream any model encoded in declarative X3DOM format without further pre-processing. We explore a number of state-of-the-art web technologies for model transmission, and compare them to the typical methods used until now. We present the advantages of each, and lay the groundwork for further extensions to our approach, towards a large-scale platform for the smooth streaming distribution of detailed 3D scenes to a large number of clients, without needing to destroy the original model Web3D format.

Energy and Resource Consumption Evaluation of Mobile Cognitive Radio Devices

This chapter proposes a Cognitive Radio network architecture that enables for the efficient operation of mobile devices over TV White Spaces. The proposed network architecture comprises of a Geo-location database and a spectrum broker that coordinates TV White Spaces access, by a number of 4G secondary communication systems, competing/requesting for the available radio spectrum. Furthermore, it introduces an innovative methodology for evaluation of energy and resource consumption in mobile cognitive devices that does not require any external metering device but exploits the advanced software and hardware features of modern smart phones to this end. In particular, the various APIs provided, by such operating systems for access to their functionality can be used for adequately auditing and reporting resource consumption on such mobile platforms. More specifically, we evaluate energy consumption and CPU utilisation in various communication scenarios via a number of experimental tests, carried out under controlled conditions. Network connectivity, calling and multimedia playback are some of the scenarios that are evaluated and presented here.

An MPEG-DASH Methodology for QoE-Aware Web3D Streaming

Recent advances in web technologies have now created a ubiquitous environment for cross-platform and cross-device multimedia applications. Media files can now be reproduced in a wide range of devices, from mobile phones to desktop computers and web-enabled televisions, using a common infrastructure. This trend towards unifying the technological infrastructure, however, has given rise to a new array of problems resulting from the varying technological capabilities of the different devices and environments. This paper, proposes an adaptive streaming framework for the display of 3D models on a wide range of web-enabled devices. The open, XML-based X3D language for 3D graphics is combined with the MPEG-DASH standard for adaptive streaming. The end result is a framework that can adaptively display 3D graphics in the face of network or computational limitations, and dynamically adapt data flow to maximize user Quality of Experience in any situation.

Applying Aesthetic Rules in Virtual Environments by Means of Semantic Web Technologies

The recent vigorous advances in virtual reality during the last decade have led to the application of 3D technologies to divergent areas such as interior decoration. Our system aims to innovate by bringing automation capabilities such as the application of high level aesthetic rules to virtual worlds. The system takes advantage of three dimensional presentation technologies for the World Wide Web such as Web3D, appropriate vocabularies such as ontology languages, semantic rule definition languages and machine learning approaches in the area of case based reasoning. The system may thus store knowledge that allow its editing tool to customize virtual worlds according to high level rules that define moods or aesthetic styles.