Brian Meyers

Wallflower: principles and practice of background maintenance

Background maintenance is a frequent element of video surveillance systems. We develop Wallflower, a three-component system for background maintenance: the pixel-level component performs Wiener filtering to make probabilistic predictions of the expected background; the region-level component fills in homogeneous regions of foreground objects; and the frame-level component detects sudden, global changes in the image and swaps in better approximations of the background. We compare our system with 8 other background subtraction algorithms. Wallflower is shown to outperform previous algorithms by handling a greater set of the difficult situations that can occur. Finally, we analyze the experimental results and propose normative principles for background maintenance.

EasyLiving: Technologies for Intelligent Environments

The EasyLiving project is concerned with development of an architecture and technologies for intelligent environments which allow the dynamic aggregation of diverse I/O devices into a single coherent user experience. Components of such a system include middleware (to facilitate distributed computing), world modelling (to provide location-based context), perception (to collect information about world state), and service description (to support decomposition of device control, internal logic, and user interface). This paper describes the current research in each of these areas, highlighting some common requirements for any intelligent environment.

Multi-camera multi-person tracking for EasyLiving

While intelligent environments are often cited as a reason for doing work on visual person-tracking, really making an intelligent environment exposes many real-world problems in visual tracking that must be solved to make the technology practical. In the context of our EasyLiving project in intelligent environments, we created a practical person-tracking system that solves most of the real-world problems. It uses two sets of color stereo cameras for tracking multiple people during live demonstrations in a living room. The stereo images are used for locating people, and the color images are used for maintaining their identities. The system runs quickly enough to make the room feel responsive, and it tracks multiple people standing, walking, sitting, occluding, and entering and leaving the space.

PreHeat: controlling home heating using occupancy prediction

Home heating is a major factor in worldwide energy use. Our system, PreHeat, aims to more efficiently heat homes by using occupancy sensing and occupancy prediction to automatically control home heating. We deployed PreHeat in five homes, three in the US and two in the UK. In UK homes, we controlled heating on a per-room basis to enable further energy savings. We compared PreHeats prediction algorithm with a static program over an average 61 days per house, alternating days between these conditions, and measuring actual gas consumption and occupancy. In UK homes PreHeat both saved gas and reduced MissTime (the time that the house was occupied but not warm). In US homes, PreHeat decreased MissTime by a factor of 6-12, while consuming a similar amount of gas. In summary, PreHeat enables more efficient heating while removing the need for users to program thermostat schedules.

WinCuts: manipulating arbitrary window regions for more effective use of screen space

Each window on our computer desktop provides a view into some information. Although users can currently manipulate multiple windows, we assert that being able to spatially arrange smaller regions of these windows could help users perform certain tasks more efficiently. In this paper, we describe a novel interaction technique that allows users to replicate arbitrary regions of existing windows into independent windows called WinCuts. Each WinCut is a live view of a region of the source window with which users can interact. We also present an extension that allows users to share WinCuts across multiple devices. Next, we classify the set of tasks for which WinCuts may be useful, both in single as well as multiple device scenarios. We present high level implementation details so that other researchers can replicate this work. And finally, we discuss future work that we will pursue in extending these ideas.

The large-display user experience

The PCs increasing graphical-processing power is fueling a demand for larger and more capable display devices. Several operating systems have supported work with multiple displays for some time. This fact, coupled with graphic-card advancements has led to an increase in multiple monitor (multimon) use. Large displays offer users significant benefits and usability challenges. In this article the authors discuss those challenges along with novel techniques to address these issues.

Detection and estimation of pointing gestures in dense disparity maps

We describe a real-time system for detecting pointing gestures and estimating the direction of pointing using stereo cameras. Previously, similar systems were implemented using color-based blob trackers, which relied on effective skin color detection; this approach is sensitive to lighting changes and the clothing worn by the user. In contrast, we used a stereo system that produces dense disparity maps in real-time. Disparity maps are considerably less sensitive to lighting changes. Our system subtracts the background, analyzes the foreground pixels to break the body into parts using a robust mixture model, and estimates the direction of pointing. We have tested the system on both coarse and fine pointing by selecting the targets in a room and controlling the cursor on a wall screen, respectively.

Display space usage and window management operation comparisons between single monitor and multiple monitor users

The continuing trend toward greater processing power, larger storage, and in particular increased display surface by using multiple monitor supports increased multi-tasking by the computer user. The concomitant increase in desktop complexity has the potential to push the overhead of window management to frustrating and counterproductive new levels. It is difficult to adequately design for multiple monitor systems without understanding how multiple monitor users differ from, or are similar to, single monitor users. Therefore, we deployed a tool to a group of single monitor and multiple monitor users to log window management activity. Analysis of the data collected from this tool revealed that usage of interaction components may change with an increase in number of monitors, and window visibility can be a useful measure of user display space management activity, especially for multiple monitor users. The results from this analysis begin to fill a gap in research about real-world window management practices.

Large display research overview

As large displays become more affordable, researchers are investigating their effects on productivity, and techniques for making the large display user experience more effective. Recent work has demonstrated significant productivity benefits, but has also identified numerous usability issues with current software design not scaling well. Studies show that larger displays enable users to create and manage many more windows, as well as to engage in more complex multitasking behavior. In this overview, various usability issues, including problems around accessing windows and icons at a distance, window management, and task management, will be discussedSeveral novel interaction techniques that address these issues and make users more productive across multiple sizes of displays will be explored.

Working Overtime: Patterns of Smartphone and PC Usage in the Day of an Information Worker

Research has demonstrated that information workers often manage several different computing devices in an effort to balance convenience, mobility, input efficiency, and content readability throughout their day. The high portability of the mobile phone has made it an increasingly valuable member of this ecosystem of devices. To understand how future technologies might better support productivity tasks as people transition between devices, we examined the mobile phone and PC usage patterns of sixteen information workers across several weeks. Our data logs, together with follow-up interview feedback from four of the participants, confirm that the phone is highly leveraged for digital information needs beyond calls and SMS, but suggest that these users do not currently traverse the device boundary within a given task.