Niels A. Nijdam

A context-aware adaptive rendering system for user-centric pervasive computing environments

In user-centric pervasive computing environments where users can utilize nearby heterogeneous devices anytime and anywhere, context-aware remote rendering is essential. It is impractical not only to manually copy 3D content from one device to another whenever a user moves, but also to render complex 3D data locally on resource-limited devices, such as mobile phones and PDAs. In this paper, we propose a context-aware adaptive rendering system which visualizes 3D content with customized user interfaces dynamically adapting to current device contexts such as processing power, memory size, display size, and network condition at runtime, while preserving the interactive performance of the 3D content. To increase the responsiveness of remote 3D rendering, we use a mechanism which temporally adjusts the quality of visualization, adapting to the current device context. By adapting the quality of visualization in terms of image quality, the overall responsiveness and frame-rate are maintained no matter the resource status. In order to overcome inevitable physical limitations of display capabilities and input controls on client devices, we provide a user interface adaptation mechanism which dynamically binds operations provided by the 3D application and user interfaces with pre-described device and application profiles. We prototyped our adaptive rendering system and experimented with a specific scenario in user-centric pervasive environments.

Collaborative telemedicine for interactive multiuser segmentation of volumetric medical images

Telemedicine has evolved rapidly in recent years to enable unprecedented access to digital medical data, such as with networked image distribution/sharing and online (distant) collaborative diagnosis, largely due to the advances in telecommunication and multimedia technologies. However, interactive collaboration systems which control editing of an object among multiple users are often limited to a simple “locking” mechanism based on a conventional client/server architecture, where only one user edits the object which is located in a specific server, while all other users become viewers. Such systems fail to provide the needs of a modern day telemedicine applications that demand simultaneous editing of the medical data distributed in diverse local sites. In this study, we introduce a novel system for telemedicine applications, with its application to an interactive segmentation of volumetric medical images. We innovate by proposing a collaborative mechanism with a scalable data sharing architecture which makes users interactively edit on a single shared image scattered in local sites, thus enabling collaborative editing for, e.g., collaborative diagnosis, teaching, and training. We demonstrate our collaborative telemedicine mechanism with a prototype image editing system developed and evaluated with a user case study. Our result suggests that the ability for collaborative editing in a telemedicine context can be of great benefit and hold promising potential for further research.

Using Blockchains to Strengthen the Security of Internet of Things

Blockchain is a distributed ledger technology that became popular as the foundational block of the Bitcoin cryptocurrency. Over the past few years it has seen a rapid growth, both in terms of research and commercial usage. Due to its decentralized nature and its inherent use of cryptography, Blockchain provides an elegant solution to the Byzantine Generals Problem and is thus a good candidate for use in areas that require a decentralized consensus among untrusted peers, eliminating the need for a central authority. Internet of Things is a technology paradigm where a multitude of small devices, including sensors, actuators and RFID tags, are interconnected via a common communications medium to enable a whole new range of tasks and applications. However, existing IoT installations are often vulnerable and prone to security and privacy concerns. This paper studies the use of Blockchain to strengthen the security of IoT networks through a resilient, decentralized mechanism for the connected home that enhances the network self-defense by safeguarding critical security-related data. This mechanism is developed as part of the Safe-Guarding Home IoT Environments with Personalised Real-time Risk Control (GHOST) project.

A general collaborative platform for mobile multi-user applications

The aim of this paper is to propose a communication middleware which makes it possible to easily and efficiently develop the networking support for multi-user applications. Even though existing middleware and development tools provides lots of functionalities to realize distributed applications, they are purely low-level services passing the most development to developers or too specialized for a specific application. It brings a challenging issue of how to support sufficient and general high-level mechanisms by the middleware. To meet different networking and interaction requirements of multiple users, our approach is to address various possibilities of the communication architecture, the user membership management, the content transmission mechanism and the event management. In each requiring feature, the proposed middleware provides several options with application-level APIs and configuration so that the different interaction needs of a multi-user application can be easily handled in the developerspsila point of view.

Coupling strategies for multi-resolution deformable meshes: expanding the pyramid approach beyond its one-way nature.

PurposeWith higher resolutions, medical image processing operations like segmentation take more time to calculate per step. The pyramid technique is a common approach to solving this problem. Starting with a low resolution, a stepwise refinement is applied until the original resolution is reached.MethodsOur work proposes a method for deformable model segmentation that generally utilizes the common pyramid technique with our improvement, to calculate and keep synchronized all mesh resolution levels in parallel. The models are coupled to propagate their changes. It presents coupling techniques and shows approaches for synchronization. The interaction with the models is realized using springs and volcanoes, and it is evaluated for the semantics of the operation to share them across the different levels.ResultsThe locking overhead has been evaluated for different synchronization techniques with meshes of individual resolutions. The partial update strategy has been found to have the least locking overhead.ConclusionRunning multiple models with individual resolutions in parallel is feasible. The synchronization approach has to be chosen carefully, so that an interactive modification of the segmentation remains possible. The proposed technique is aimed at making medical image segmentation more usable while delivering high performance.

The CaMeLi Framework—A Multimodal Virtual Companion for Older Adults

Artificial Social Companions are a promising solution for the increasing challenges in elderly care. This chapter describes the CaMeLi autonomous conversational agent system which simulates human-like affective behaviour and acts as a companion for older adults living alone at home. The agent employs synthetic speech, gaze, facial expressions, and gestures to support multimodal natural interaction with its users and assists them in a number of daily life scenarios.We present the agent’s overall architecture, with a focus on the perception, decision making and synthesis components which give rise to the agent’s intelligent affective behavior. The agent was evaluated in an exploratory study where it was introduced in 20 homes of older adults (aged 65+) in three European countries (Switzerland, the Netherlands, Portugal) for a total duration of 12 weeks. We present the results of the evaluation study with regards to acceptance, perceived usability, and usefulness of the agent, and discuss future opportunities for fellow researchers who are striving to bring virtual agents out of the laboratories into successful real world applications.

An application framework for adaptive distributed simulation and 3D rendering services

With the increase in mobile computing devices, the expectancy of accessing media on all these devices requires the support of various interaction types, flexible data couplings, and transparent context adaptation. To meet those requirements, in this paper, we propose a flexi-ble framework offering a context aware adaptive rendering model. We introduce a node based service deployment in order to overcome the scalability and easy extensibility in terms of development, unified event messaging and management aims at preserving optimal inter-activity and dynamic adaptation of the 3D content streaming. We defined an online cloth simulation scenario and pro-totyped the above proposed service framework.

An Application Framework for Seamless Synchronous Collaboration Support in Ubiquitous Computing Environments

Dynamic and heterogeneous nature of ubiquitous computing environments introduces additional requirements to support synchronous collaboration. Such requirements include support of various interaction types, flexible data couplings, and transparent context adaptation. To meet those requirements, in this paper, we propose the manipulation based application model. In comparison to the presentation semantics split model [5], we introduce the manipulation in between the presentation and shared semantics. A manipulation is a fragment of the semantics, which is dynamically created when a presentation requires personalized interaction to the shared semantics. A manipulation enables transparent context adaptation by migrating its states to a new manipulation of the different presentation to adapt the current context, e.g., user location change. We prototyped the proposed application framework and tested the feasibility of the framework.

InterMedia: Towards Truly User-Centric Convergence of Multimedia

In this paper, we present an interactive media with personal networked devices (InterMedia) which aims to progress towards truly user-centric convergence of multimedia system. Our vision is to make the user as a multimedia central to access multimedia anywhere and anytime exploiting diverse devices. To realize the user-centric convergence, we defined three key challenging issues: dynamic distributed networking, mobile and wearable interfaces, and multimedia adaptation and handling. Each field of interest investigates a transparent access to diverse networks for seamless multimedia session migration, a flexible wearable platform that supports dynamic composition of diverse wearable devices and sensors, as well as the adaptation of diverse multimedia contents based on the user’s personal and device contexts. To prove our goals, we prototyped our scenario, called Chloe@University, which included interactive 3D multimedia manipulation with seamless session mobility, modular wearable interfaces with DRM, contextual bookmark with mobile interfaces, and interactive surfaces and remote displays which aim to overcome the limited output capabilities of mobile devices.