Wolfgang Stuerzlinger

High dynamic range display systems

The dynamic range of many real-world environments exceeds the capabilities of current display technology by several orders of magnitude. In this paper we discuss the design of two different display systems that are capable of displaying images with a dynamic range much more similar to that encountered in the real world. The first display system is based on a combination of an LCD panel and a DLP projector, and can be built from off-the-shelf components. While this design is feasible in a lab setting, the second display system, which relies on a custom-built LED panel instead of the projector, is more suitable for usual office workspaces and commercial applications. We describe the design of both systems as well as the software issues that arise. We also discuss the advantages and disadvantages of the two designs and potential applications for both systems.

MMR: an interactive massive model rendering system using geometric and image-based acceleration

We present a system for rendering very complex 3D models at interactive rates. We select a subset of the model as preferred viewpoints and partition the space into virtual cells. Each cell contains near geometry, rendered using levels of detail and visibility culling, and far geometry, rendered as a textured depth mesh. Our system automatically balances the screen-space errors resulting from geometric simplification with those from textureddepth-mesh distortion. We describe our prefetching and data management schemes, both crucial for models significantly larger than available system memory. We have successfully used our system to accelerate walkthroughs of a 13 million triangle model of a large coal-fired power plant and of a 1.7 million triangle architectural model. We demonstrate the walkthrough of a 1.3 GB power plant model with a 140 MB cache footprint.

User interface façades: towards fully adaptable user interfaces

User interfaces are becoming more and more complex. Adaptable and adaptive interfaces have been proposed to address this issue and previous studies have shown that users prefer interfaces that they can adapt to self-adjusting ones. However, most existing systems provide users with little support for adapting their interfaces. Interface customization techniques are still very primitive and usually constricted to particular applications. In this paper, we present User Interface Façades, a system that provides users with simple ways to adapt, reconfigure, and re-combine existing graphical interfaces, through the use of direct manipulation techniques. The paper describes the users view of the system, provides some technical details, and presents several examples to illustrate its potential.

3D User Interfaces: New Directions and Perspectives

Three-dimensional user interfaces (3D UIs) let users interact with virtual objects, environments, or information using direct 3D input in the physical and/or virtual space. In this article, the founders and organizers of the IEEE Symposium on 3D User Interfaces reflect on the state of the art in several key aspects of 3D UIs and speculate on future research.

Effects of tracking technology, latency, and spatial jitter on object movement

We investigate the effects of input device latency and spatial jitter on 2D pointing tasks and 3D object movement tasks. First, we characterize jitter and latency in a 3D tracking device and an optical mouse used as a baseline comparison. We then present an experiment based on ISO 9241-9, which measures performance characteristics of pointing devices. We artificially introduce latency and jitter to the mouse and compared the results to the 3D tracker. Results indicate that latency has a much stronger effect on human performance than low amounts of spatial jitter. In a second study, we use a subset of conditions from the first to test latency and jitter on 3D object movement. The results indicate that large, uncharacterized jitter “spikes” significantly impact 3D performance.

Analysis of text entry performance metrics

Researchers have proposed many text entry systems to enable users to perform this frequent task as quickly and precise as possible. Unfortunately the reported data varies widely and it is difficult to extract meaningful average entry speeds and error rates from this body of work. In this article we collect data from well-designed and well-reported experiments for the most important text entry methods, including those for handheld devices. Our survey results show that thumb keyboard is the fastest text entry method after the standard QWERTY keyboard, and that Twiddler is fastest amongst non-QWERTY methods. Moreover, we survey how text entry errors were handled in these studies. Finally, we conducted a user study to detect which effect different error-handling methodologies have on text entry performance metrics. Our study results show that the way human errors are handled has indeed a significant effect on all frequently used error metrics.

The tradeoff between spatial jitter and latency in pointing tasks

Interactive computing systems frequently use pointing as an input modality, while also supporting other forms of input such as alphanumeric, voice, gesture, and force. We focus on pointing and investigate the effects of input device latency and spatial jitter on 2D pointing speed and accuracy. First, we characterize the latency and jitter of several common input devices. Then we present an experiment, based on ISO 9241-9, where we systematically explore combinations of latency and jitter on a desktop mouse to measure how these factors affect human performance. The results indicate that, while latency has a stronger effect on human performance compared to low amounts of spatial jitter, jitter dramatically increases the error rate, roughly inversely proportional to the target size. The findings can be used in the design of pointing devices for interactive systems, by providing a guideline for choosing parameters of spatial filtering to compensate for jitter, since stronger filtering typically also increases lag. We also describe target sizes at which error rates start to increase notably, as this is relevant for user interfaces where hand tremor or similar factors play a major role.

The Hedgehog: a novel optical tracking method for spatially immersive displays

Existing commercial technologies do not adequately meet the requirements for tracking in fully enclosed Virtual Reality displays. We present a novel six degree of freedom tracking system, the Hedgehog; which overcomes several limitations inherent in existing sensors and tracking technology. The system reliably estimates the pose of the users head with high resolution and low spatial distortion. Light emitted from an arrangement of lasers projects onto the display walls. An arrangement of cameras images the walls and the two-dimensional centroids of the projections are tracked to estimate the pose of the device. The system is able to handle ambiguous laser projection configurations, static and dynamic occlusions of the lasers, and incorporates an auto-calibration mechanism due to the use of the SCAAT (single constraint at a time) algorithm. A prototype system was evaluated relative to a state-of-the-art motion tracker and showed comparable positional accuracy (12 mm RMS) and significantly better absolute angular accuracy (0.1 RMS).

SESAME: towards better 3D conceptual design systems

Conceptual design dominates the early stages of most creative design processes. During these stages, the designer makes important decisions about the parameters of a model that are aimed at satisfying a set of design criteria. To do this, the designer produces many sketches of various possible solutions. Meanwhile, computer-aided design (CAD) systems are becoming the dominant visual medium used in design practice. However, these tools evolved as documentation production tools and do not support conceptual thinking. This paper presents a list of guidelines for computer support for conceptual design activities on 3D scenes and presents SESAME (Sketch, Extrude, Sculpt, and Manipulate Easily), a system based on these guidelines. Finally, we present a user study comparing SESAME with a conventional CAD package to demonstrate the effectiveness of SESAME.

The Value of Constraints for 3D User Interfaces

User interfaces to three-dimensional environments are becoming more and more popular. Today this trend is fuelled through the introduction of social communication via virtual worlds, console and computer games, as well as 3D televisions.