Thomas Psik

Global contrast factor - a new approach to image contrast

Contrast in image processing is usually defined as a ratio between the darkest and the brightest spots of an image. In this paper we introduce a different contrast definition. The newly introduced Global Contrast Factor (GCF) corresponds closer to the human perception of contrast. GCF uses contrasts at various resolution levels in order to compute overall contrast. Experiments were conducted in order to find weight factors needed to calculate GCF. GCF measures richness of detail as perceived by a human observer, and as such can be used in various application areas like rendering, tone mapping, volume visualization, and lighting design.

Agents that talk and hit back: animated agents in augmented reality

AR puppet is a hierarchical animation framework for augmented reality agents, which is a research area combining augmented reality (AR), sentient computing and autonomous animated agents into a single coherent human-computer interface paradigm. While sentient computing systems use the physical environment as an input channel, AR outputs virtual information superimposed on real world objects. To enhance man-machine communication with more natural and efficient information presentation, this framework adds animated agents to AR applications that make autonomous decisions based on their perception of the real environment. These agents are able to turn physical objects into interactive, responsive entities collaborating with both anthropomorphic and non-anthropomorphic virtual characters, extending AR with a previously unexplored output modality. AR puppet explores the requirements for context-aware animated agents concerning visualization, appearance, behavior, in addition to associated technologies and application areas. A demo application with a virtual repairman collaborating with an augmented LEGO/spl reg/ robot illustrates our concepts.

Supporting configurability in a mixed-media environment for design students

In many environments, the landscape of space and artefacts is evolving and changing with the tasks at hand. Integrating digital media and computation in these environments has to take into account the fact that people will configure space functions and tools according to the situation, organising use in unexpected ways. In this article, we present and discuss how the issue of configurability is dealt with, in a series of field trials with design students. The aim of these trials was to construct, for architecture and interaction design students, a mixed-media environment for inspirational learning. The results include physical infrastructure in space and in furniture as integral parts of the interaction technology and the creation of composite representations called “mixed objects‘’, which blend digital and non-digital media in one design artefact. Configurability has to be supported at different levels (infrastructures, artefacts, functions) and across the physical and digital realms.

A manifesto for the performative development of ubiquitous media

This paper addresses design agendas in Human-Computer Interaction and neighbouring fields motivated by the mixing of areas that were mostly kept separate until recently, such as media studies, performing arts, computing, and ubiquitous or tangible interfaces. Referring to new developments in this interdisciplinary research area, and moving from three specific design cases, this paper proposes a critical design agenda that pragmatically joins: concepts from media studies, tangible or ubiquitous media design concerns, anthropological perspectives to performance and practices of theatre performance.

The ColorTable : a design story

The paper describes the design story of the ColorTable, a tangible user interface in support of urban planners and diverse stakeholders collaboratively envisioning urban change, which was developed in an iterative process of design-evaluation-feedback-redesign in a series of workshops with users in the context of real urban planning projects. It seeks to clarify a number of more general design issues related to tangible user interfaces -- how to make use of material and spatial properties in designing both, physical interface and multiple and simultaneous interactions; how to handle the complexity of urban projects while keeping interfaces and interactions simple and transparent.

Expressive interactions - supporting collaboration in urban design

This paper discusses technological interventions in support of planners, citizens and other stakeholders in envisioning and nego-tiating an urban project. A set of prototypal tools, including a tangible user interface, has been developed that allow users to create and manipulate visual/auditory scenes and mesh these scenes with the real environment of an urban site. The paper discusses how toallsupport users - different types of stakeholders - in the collaborative creation of mixed reality configurations as an integral part of expressing their ideas about an urban project, distinguishing between different types and levels of cooperation. It also looks into how to use mixed reality tools for enhancing an already highly developed representational culture.

Using ARToolKit markers to build tangible prototypes and simulate other technologies

Quick prototyping of tangible user interfaces is currently hampered by availability of toolkits and the double challenge of tinkering with software and hardware. While software may be downloaded, hardware cannot. As a work-around for a class on experimental prototyping of tangible appliances we utilized the ARToolKit that tracks optical markers. By creatively adapting it, our students quickly developed working prototypes, simulating a range of devices and tracking technologies. Our approach enabled a focus on quick prototyping, idea testing and simulation of the interaction process. We explain our reasons for using the ARToolKit, summarize its advantages and disadvantages, present four students projects, and discuss our experiences and conclusions. In particular we found that visual tracking has the advantage not to limit or determine possible interaction styles and thus fosters designing richer interaction. We discuss this as a requirement for future tangible prototyping toolkits.

Tangible Image Query

This paper introduces a tangible user interface for browsing and retrieving images from an image database. The basis for the query to the image database is a color layout sketch, which is used by the underlying query algorithm to find the best matches. The users are provided with colored cubes of various sizes and colors. The users can place and arrange the colored cubes on a small table to create a color layout sketch. Multiple users can use this interface to collaborate in an image query. To evaluate the benefits of the interface, it is compared to a traditional GUI application in which the users use a mouse to paint a color layout sketch. The tangible interface appears to be easier to use and better accepted by people who belive they are unable to draw or paint or who do not want to use computer.

The 3D Wunderkammer: an indexing by placing approach to the image storage and retrieval

The explosion of storage media size and spread of the Internet have resulted in a huge amount of images and multimedia material that an average user has to deal with. The traditional use of filenames and directories is no longer sufficient. In contrast to keywording and a kind of content-based image retrieval, we introduce a novel approach to storing and retrieving images, and other multimedia material using an indexing by placing mechanism. The idea is to let the user place images in the 3D environment, where the user can easily find them again. The images can be collected, modified, and grouped together. The principles described in the paper are implemented in the 3D Wunderkammer system, a multi-user client-server application. The server is completely written in Java and the client runs in a standard Web browser with a standard VRML plug-in.

The invisible person: advanced interaction using an embedded interface

In this paper we describe an advanced user interface enabling even playing games in an immersive virtual environment. There are no common input devices, users presence in the environment, movements, and body postures are the available tools for interaction. Furthermore, a publicly accessible installation in the Vienna Museum of Technology implementing such an advanced environment is described. In this installation computers are completely hidden, and it is one of the most popular exhibits in the museum, which has been accessed by more than 200,000 visitors since September 1999.