Andriy Pavlovych

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.

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.

A high-dynamic range projection system

The dynamic range in many real-world environments surpasses the capabilities of traditional display technologies by several orders of magnitude. Recently, a novel display capable of displaying images with a dynamic range much closer to real world situations has been demonstrated. This was achieved through a spatially modulated backlight behind an LCD panel. Combined with the modulating power of the LCD panel itself, this enabled the display of much higher contrast compared to an LCD panel with a spatially uniform backlight. In this paper, we describe a further development of the technology, namely a high dynamic range projection system. This makes such display systems more widely applicable as any surface can be used for the display of high dynamic range images. Our new system is designed as an external attachment to a regular DLPTM-based projector, which allows the use of unmodified projectors. It works by adapting the projected image via a set of lenses to form a small image. This small image is then modulated via an LCD panel and the result is projected via another lens system onto a larger screen, as in traditional projection scenarios. The double modulation, by the projector and the LCD panel together, creates a high dynamic range image and an ANSI contrast of over 700:1. Finally, we discuss the advantages and disadvantages of our design relative to other high and low dynamic range display technologies and its potential applications.

The design and realization of CoViD: a system for collaborative virtual 3D design

Many important decisions in the design process are made during fairly early on, after designers have presented initial concepts. In many domains, these concepts are already realized as 3D digital models. Then, in a meeting, the stakeholders for the project get together and evaluate these potential solutions. Frequently, the participants in this meeting want to interactively modify the proposed 3D designs to explore the design space better. Today’s systems and tools do not support this, as computer systems typically support only a single user and computer-aided design tools require significant training. This paper presents the design of a new system to facilitate a collaborative 3D design process. First, we discuss a set of guidelines which have been introduced by others and that are relevant to collaborative 3D design systems. Then, we introduce the new system, which consists of two main parts. The first part is an easy-to-use conceptual 3D design tool that can be used productively even by naive users. The tool provides novel interaction techniques that support important properties of conceptual design. The user interface is non-obtrusive, easy-to-learn, and supports rapid creation and modification of 3D models. The second part is a novel infrastructure for collaborative work, which offers an interactive table and several large interactive displays in a semi-immersive setup. It is designed to support multiple users working together. This infrastructure also includes novel pointing devices that work both as a stylus and a remote pointing device. The combination of the (modified) design tool with the collaborative infrastructure forms a new platform for collaborative virtual 3D design. Then, we present an evaluation of the system against the guidelines for collaborative 3D design. Finally, we present results of a preliminary user study, which asked naive users to collaborate in a 3D design task on the new system.

Effect of screen configuration and interaction devices in shared display groupware

Interactive tabletop and wall surfaces support collaboration and interactivity in novel ways. Apart from keyboards and mice, such systems can also incorporate other input devices, namely laser pointers, marker pens with screen location sensors, or touch-sensitive surfaces. Similarly, instead of a vertically positioned desktop monitor, collaborative setups typically use much larger displays, which are oriented either vertically (wall) or horizontally (tabletop), or combine both kinds of surfaces. In this paper we describe an empirical study that investigates how technical system constraints can affect group performance in high pace collaborative tasks. For this, we compare various input and output modalities in a system that consists of several interactive tabletop and wall surface(s). We observed that the performance of a group of people scaled almost linearly with the number of participants on an almost perfectly parallel task. We also found that mice were significantly faster than laser pointers, but only by 21%. Also, interaction on walls was significantly faster than on the tabletop, by 51%.

Improving digital handoff using the space above the table

Object handoff - that is, passing an object or tool to another person - is an extremely common activity in collaborative tabletop work. On digital tables, object handoff is typically accomplished by sliding them on the table surface - but surface-only interactions can be slow and error-prone, particularly when there are multiple people carrying out multiple handoffs. An alternative approach is to use the space above the table for object handoff; this provides more room to move, but requires above-surface tracking. We have developed two above-the-surface handoff techniques that use simple and inexpensive tracking: a force-field technique that uses a depth camera to determine hand proximity, and an electromagnetic-field technique called ElectroTouch that provides positive indication when people touch hands over the table. We compared the new techniques to three kinds of surface-only handoff (sliding, flicking, and surface-only Force-Fields). The study showed that the above-surface techniques significantly improved both speed and accuracy, and that ElectroTouch was the best technique overall. This work provides designers with practical new techniques for substantially increasing performance and interaction richness on digital tables.