Document Server@UHasselt
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Repository of the University of Hasselt containing publications in the fields of statistics, computer science, information strategies and material from the Institute for behavioural sciences.
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1.
A genetic algorithm for the non-parametric inversion of strong lensing systems - LIESENBORGS, Jori; De Rijcke, S; Dejonghe, H
We present a non-parametric technique to infer the projected mass distribution of a gravitational lens system with multiple strong-lensed images. The technique involves a dynamic grid in the lens plane on which the mass distribution of the lens is approximated by a sum of basis functions, one per grid cell. We used the projected mass densities of Plummer spheres as basis functions. A genetic algorithm then determines the mass distribution of the lens by forcing images of a single source, projected back on to the source plane, to coincide as well as possible. Averaging several tens of solutions removes the...
2.
Non-parametric inversion of gravitational lensing systems with few images using a multi-objective genetic algorithm - LIESENBORGS, Jori; De Rijcke, S; Dejonghe, H; Bekaert, P
Galaxies acting as gravitational lenses are surrounded by, at most, a handful of images. This apparent paucity of information forces one to make the best possible use of what information is available to invert the lens system. In this paper, we explore the use of a genetic algorithm to invert in a non-parametric way strong lensing systems containing only a small number of images. Perhaps the most important conclusion of this paper is that it is possible to infer the mass distribution of such gravitational lens systems using a non-parametric technique. We show that including information about the null space...
3.
From dust till drawn - A real-time bidirectional pastel simulation - VAN HAEVRE, William; VAN LAERHOVEN, Tom; DI FIORE, Fabian; VAN REETH, Frank
We present a system for drawing pastel media in realtime as an effective alternative to most existing digital solutions that basically allow for drawing arbitrary strokes in a particular style. Our approach is focused on the simulation of the natural material itself and on its interaction with the drawing surface and the drawing tool. Upon free-form drawing, a bidirectional transfer of pigment takes place. In one direction, the paper surface is dusted with new pigment particles broken off the tip (i.e., the end of the drawing tool). A large part of these particles will be deposited or blended together with...
4.
Screen-camera calibration using a spherical mirror - FRANCKEN, Yannick; HERMANS, Chris; BEKAERT, Philippe
Recent developments in the consumer market have indicated that the average user of a personal computer is likely to also own a webcam. With the emergence of this new user group will come a new set of applications, which will require a user-friendly way to calibrate the position of the camera with respect to the location of the screen. This paper presents a fully automatic method to calibrate a screen-camera setup, using a single moving spherical mirror. Unlike other methods, our algorithm needs no user intervention other then moving around a spherical mirror In addition, if the user provides the...
5.
Interactive Data Units: A Framework to Support Rich Graphical Data Presentations on Heterogeneous Devices - HOUBEN, Geert; DI FIORE, Fabian; LUYTEN, Kris; VAN REETH, Frank; CONINX, Karin
The use of mobile computing systems continues to increase among a wider diversity of end-users. On desktop computers, a lot of research in the area of interactive visualization of graphical information has been done, but there is a growing opportunity to have the possibility of creating scalable and animated graphical data presentations on heterogeneous mobile devices. Latest trends in the mobile phone and PDA community (e.g. games and MMS) emphasize the demand for a better support of such rich graphical data that is scalable over multiple platforms. In this paper we present plastic mobile services for the automotive after sales...
6.
Towards an Integrated Development Environment for Context-Aware User Interfaces - CLERCKX, Tim; CONINX, Karin
The emergence of mobile computing devices brings along the fact that users interact with computers in various environments. The user interface of a mobile system can be affected by environmental context. Several approaches succeed in providing architectures and frameworks to support the building and reuse of software components considering context information. Taking into account context information in designing the interaction of a system, however, has not yet been extensively investigated. In this paper we will discuss an Integrated Development Environment, DynaMo-AID, we are developing to support the design, prototyping, evaluation and deployment of context-aware interactive systems.
7.
Context-sensitive User Interfaces for Ambient Environments: Design, Development and Deployment - LUYTEN, Kris; VANDERVELPEN, Chris; VAN DEN BERGH, Jan; CONINX, Karin
There is a growing demand for design support to create interactive systems that are deployed in ambient intelligent environments. Unlike traditional interactive systems, the wide diversity of situations these type of user interfaces need to work in require tool-support that is close to the environment of the end-user on the one hand and provide a smooth integration with the application logic on the other hand. This paper shows how the Model-Based User Interface Development methodology can be applied for ambient intelligent environments; we propose a task-centered approach towards the design of interactive systems by means of appropriate visualizations and simulations...
8.
Constraint Adaptability of Multi-Device User Interface - LUYTEN, Kris; VERMEULEN, Jo; CONINX, Karin
Methods to support the creation of multi-device user interfaces typically use some type of
abstraction of the user interface design. To retrieve the final user interface from the
abstraction a transformation will be applied that specializes the abstraction for a particular
target platform. The User Interface Markup Language (UIML) offers a way to create multidevice
user interface descriptions while maintaining the consistency of certain aspects of a
user interface across platforms. We extended the UIML language with support for layout
constraints. Designers can create layout templates based on constraints that limit the ways a user interface can rearrange across platforms. This results in a higher degree...
9.
A generic approach for multi-device user interface rendering with UIML - LUYTEN, Kris; THYS, Kristof; VERMEULEN, Jo; CONINX, Karin
We present a rendering engine for displaying graphical user interfaces on multiple devices. The renderer interprets a standardized XML-based user interface description language: the User Interface Markup Language (UIML). A generic architecture for the renderer is defined so that deployment of the engine on different devices implies only little effort. We show that our rendering engine can be used on iDTV set-top boxes, mobile phones, PDAs and desktop PCs, and smoothly integrates with both local and remote application logic. As a test bed for the UIML specification we also explore support for extensions to UIML that enable the user interface...
10.
Making Bits and Atoms Talk Today: A Practical Architecture for Smart Object Interaction - VERMEULEN, Jo; Thys, R.; LUYTEN, Kris; CONINX, Karin
Bringing together the physical and digital worlds has been the subject of research for some time now. In particular, a number of successful prototypes that link physical objects with digital information (often called smart object systems) have already been presented. However, a generally accepted architecture to design such systems has not yet emerged. This paper presents a reusable and practical framework for developing smart object applications today. At the basis of our approach lies the use of Semantic Web technology to drive interaction between the physical and digital worlds. We used this framework to develop SemaNews, a novel application that...
11.
Ad-hoc Co-located Collaborative Work with Mobile Devices - LUYTEN, Kris; VERPOORTEN, Kristof; CONINX, Karin
This paper presents how ad-hoc co-located collaborations can be supported with an arbitrary number of users that only have access to small-size mobile displays. Our approach is based on tracking of these personal displays that share the same information space. All displays involved in the collaboration act as autonomous windows on a set of data items (the information space) positioned on a shared virtual canvas. Data items are identified by their three-dimensional location in physical space and can be manipulated through the displays that serve as windows on the shared canvas. Each display is tracked in physical space and is...
12.
Mixed Initiative Ambient Environments: A Self-Learning System to Support User Tasks in Interactive Environments - VERPOORTEN, Kristof; LUYTEN, Kris; CONINX, Karin
In this paper we introduce a pro-active self-learning agent system that supports the user in an ambient intelligence environment. Interaction in an ambient intelligence environment is typically very complex and demands lots of attention of the end-user. In many cases it is extremely difficult for the user to evaluate what the consequences are from interactions accomplished in this space. In the system we present in this paper, an agent monitors the user's interactions with the environment to learn the user's expectations when certain activities are performed. Machine learning techniques allow the system to pro-actively react on behalf of the user....
13.
Sharing Visual Information in Virtual Environments using Projective Texture Mapping - FRANCKEN, Yannick; HUYSMANS, Johan; BEKAERT, Philippe
We present a method for sharing visual information in 3D virtual environments, using a projective texture mapping based method. Avatars can share information with other avatars by projecting relevant information into the environment. In addition to standard projective texture mapping, an important depth cue is added: projected light is attenuated in function of the light-travel distance. This is efficiently accomplished on a per vertex basis by adaptively super-sampling under-sampled polygons. This way, the projection quality is maximized while keeping a fixed frame rate. Our technique is implemented into the Quake III engine, extending its shading language with GLSL fragment and...
14.
More effective image matching with Scale Invariant Feature Transform - ANCUTI, Cosmin; BEKAERT, Philippe
Feature matching is based on finding reliable corresponding points in the images. This requires to solve a twofold problem: detecting repeatable feature points and describing them as distinctive as possible. SIFT (Scale Invariant Feature Transform) has been proven to be the most reliable solution to this problem. It combines a scale invariant detector and a very robust descriptor based on gray image gradients. Even if in general the detected SIFT feature points have a repeatability score greater than 40 %, an important proportion of them are not identified as good corresponding points by the SIFT matching procedure. In this paper...
15.
Delivering Multi-device Synchronised Interactive Services in a Broadcasting Environment through UIML Deployment - Leroux, Ph.; Verstraete, V.; De Turck, F.; THYS, Kristof; LUYTEN, Kris
As the variety in network service platforms and end user devices grows rapidly, content providers must constantly adapt their production system to support these new technologies. A factor that highly complicates this process is the need for interactivity. In the Multimedia Content Distribution Platform (MCDP) Project, an architecture for deploying highly interactive and synchronised television programs over a diverse collection of broadcast networks and end user devices was developed. It consists of a middleware platform with pluggable support for new broadcast networks and end-user devices, whilst preserving synchronised interactivity. In order to support a maximum of functionality and use cases;...
16.
Service-interaction Descriptions: Augmenting Services with User Interface Models - VERMEULEN, Jo; VANDRIESSCHE, Yves; CLERCKX, Tim; LUYTEN, Kris; CONINX, Karin
Semantic service descriptions have paved the way for flexible interaction with services in a mobile computing environment. Services can be automatically discovered, invoked and even composed. On the contrary, the user interfaces for interacting with these services are often still designed by hand. This approach poses a serious threat to the overall flexibility of the system. To make the user interface design process scale, it should be automated as much as possible. We propose to augment service descriptions with high-level user interface models to support automatic user interface adaptation. Our method builds upon OWL-S, an ontology for Semantic Web Services,...
17.
Tangible Mashups: Exploiting Links between the Physical and Virtual World - VERMEULEN, Jo; LUYTEN, Kris; CONINX, Karin
The link between corresponding physical and virtual worlds has been the subject of research for many years now. The instantiation of this link was often a complex task that involved special purpose techniques to identify and search for the virtual information that belongs to a selected physical object. It is since the conception of physical tagging technologies such as RFID that physical objects can carry their own virtual information. In this paper we show a simple yet effective approach to extract the virtual information of physical objects and aggregate it in a sensible way for the user. We rely on...
18.
A web-based central gateway infrastructure in the automotive after-sales market - Business interoperability through the web - HOUBEN, Geert; LUYTEN, Kris; CONINX, Karin; Schoenherr, Frank
The Block Excemption Regulation of the European Commission was enacted in 2002 with the goal to strengthen competition between dependent and independent repairers in the automotive after-sales market. The FP6 MYCAREVENT project embraces these goals while triggering new business opportunities by establishing a mobile accessible infrastructure as single gateway to different kinds of resources. This information procurement framework allows customers to find specific vehicle repair and diagnostic data from different car manufacturers and 3(rd) parties in the same way. In order to provide a higher degree of accessibility, extensibility and adaptivity, our service-oriented infrastructure presented in this paper is web-based...
19.
Convolution Shadow Maps - Annen, Thomas; MERTENS, Tom; BEKAERT, Philippe; Seidel, H.P.; Kautz, J.
We present Convolution Shadow Maps, a novel shadow representation that affords efficient arbitrary linear filtering of shadows. Traditional shadow mapping is inherently non-linear w.r.t. the stored depth values, due to the binary shadow test. We linearize the problem by approximating shadow test as a weighted summation of basis terms. We demonstrate the usefulness of this representation, and show that hardware-accelerated anti-aliasing techniques, such as tri-linear filtering, can be applied naturally to Convolution Shadow Maps. Our approach can be implemented very efficiently in current generation graphics hardware, and offers real-time frame rates.
20.
High-Level Modeling of Multimodal Interaction Techniques Using NiMMiT - DE BOECK, Joan; VANACKEN, Davy; RAYMAEKERS, Chris; CONINX, Karin
The past few years, multimodal interaction has been gaining importance in virtual environments. Although multimodality renders interacting with an environment more natural and intuitive, the development cycle of such an application is often long and expensive. In our overall field of research, we investigate how model-based design can facilitate the development process by designing environments through the use of high-level diagrams. In this scope, we present NiMMiT?, a graphical notation for expressing and evaluating multimodal user interaction; we elaborate on the NiMMiT primitives and demonstrate its use by means of a comprehensive example.
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