Athanasios G. Malamos

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.

Extending MPEG-7 for efficient annotation of complex web 3D scenes

In this paper, we propose an annotation scheme for web-3D scenes based on the MPEG-7 standard. We focus on the annotation of 3D scenes that are encoded with the X3D modeling language which is the descendant of VRML. X3D has been adopted by the web service industry as the appropriate framework for developing internet friendly and flexible 3D visualization applications. We introduce MPEG-7 extensions that are necessary in order to fulfill the requirements of the X3D scene structure and we adapt the MPEG-7 schema encoding accordingly. In the annotation scheme, we consider animation and interactivity issues along with geometrical and appearance characteristics of the 3D content providing a more efficient description of the scene. Thus, the extensions proposed in this paper cover all the information required for a complete and efficient description on the position and relative size of 3D objects, specific characteristics such as object type, curvature properties and available textures, combined with the objects’ innate animation properties and its interactions with other objects in the scene or with the end user. The extensions are MPEG-7 Visual and Metadata Descriptors, which fully conform to the standardization restrictions, and we also provide the modifications to the corresponding schema of the ISO 15938 standard that are essential for validating against the proposed MPEG-7 implementation.

Direct mapping of X3D scenes to MPEG-7 descriptions

Content description is an important step in multimedia indexing and search applications. While, in the past, a large volume of research has been devoted to image, audio, and video data, 3D scenes have received relatively little attention. In this paper, we present a methodology for the automatic description of 3D scenes, based on textual metadata but also their shape, structure, color, animation, lighting, viewpoint, texture and interactivity content. Our system accepts 3D scenes as input, written in the open X3D standard for web graphics, and automatically builds MPEG-7 descriptions. In order to fully model 3D content, we draw upon our previous work, where we have extended the MPEG-7 standard with multiple 3D-specific descriptors. Here, we further extend MPEG-7, and present our approach for automatic descriptor extraction. We take advantage of the fact that both X3D and MPEG-7 are written in XML, and base our automatic extraction system on eXtensible Stylesheet Language Transformations (XSLT). We have incorporated our system into a large-scale platform for VR advertising over the web, where the benefits of automatic annotation can be twofold: authors are offered better access to stored 3D material, for editing and reuse, and end users can be provided with advertisements whose semantic content matches their profile.

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.

An alternative approach for statistical single-label document classification of newspaper articles

Text classification is one of the most important sectors of machine learning theory. It enables a series of tasks among which are email spam filtering and context identification. Classification theory proposes a number of different techniques based on different technologies and tools. Classification systems are typically distinguished into single-label categorization and multi-label categorization systems, according to the number of categories they assign to each of the classified documents. In this paper, we present work undertaken in the area of single-label classification which resulted in a statistical classifier, based on the Naive Bayes assumption of statistical independence of word occurrence across a document. Our algorithm, takes into account cross-category word occurrence in deciding the class of a random document. Moreover, instead of estimating word co-occurrence in assigning a class, we estimate word contribution for a document to belong in a class. This approach outperforms other statistical classifiers as Naive Bayes Classifier and Language Models, as proven in our results.

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.

Enhancing X3DOM declarative 3D with rigid body physics support

Given that physics can be fundamental for realistic and interactive Web3D applications, a number of JavaScript versions of physics engines have been introduced during the past years. This paper presents the implementation of the rigid body physics component, as defined by the X3D specification, in the X3DOM environment, and the creation of dynamic 3D interactive worlds. We briefly review the state of the art in current technologies for Web3D graphics, including HTML5, WebGL and X3D, and then explore the significance of physics engines in building realistic Web3D worlds. We include a comprehensive review of JavaScript physics engine libraries, and proceed to summarize the significance of our implementation while presenting in detail the methodology followed. The results obtained so far from our cross-browser experiments demonstrate that real-time interactive scenes with hundreds of rigid bodies can be constructed and operate with acceptable frame rates, while the allowing the user to maintain the scene control.

HOLISTIC: An IoT system for residential water recycling based on open source technologies

This paper presents the design and implementation of a novel IT system that aims to monitor, control and manage residential water infrastructures. Even though reusing water and environmental resources has been a hot matter during the last years, there have been few cases where relative and innovative technologies have been applied. More specifically, the system can manage water flows coming from any source in the complex of building and redirect them to tanks or consumption points. The system may thus maximize water recycling and minimize costs for water and also offer recycling automation and policies for individual parts of residential complexes.

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.