UIST2.0 Archive - 20 years of UIST
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heart rate

In Proceedings of UIST 2010
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Jogging over a distance between Europe and Australia (p. 189-198)

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Exertion activities, such as jogging, require users to invest intense physical effort and are associated with physical and social health benefits. Despite the benefits, our understanding of exertion activities is limited, especially when it comes to social experiences. In order to begin understanding how to design for technologically augmented social exertion experiences, we present "Jogging over a Distance", a system in which spatialized audio based on heart rate allowed runners as far apart as Europe and Australia to run together. Our analysis revealed how certain aspects of the design facilitated a social experience, and consequently we describe a framework for designing augmented exertion activities. We make recommendations as to how designers could use this framework to aid the development of future social systems that aim to utilize the benefits of exertion.

rate control

In Proceedings of UIST 2000
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Speed-dependent automatic zooming for browsing large documents (p. 139-148)

recognition rate

In Proceedings of UIST 2007
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Gestures without libraries, toolkits or training: a $1 recognizer for user interface prototypes (p. 159-168)

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Although mobile, tablet, large display, and tabletop computers increasingly present opportunities for using pen, finger, and wand gestures in user interfaces, implementing gesture recognition largely has been the privilege of pattern matching experts, not user interface prototypers. Although some user interface libraries and toolkits offer gesture recognizers, such infrastructure is often unavailable in design-oriented environments like Flash, scripting environments like JavaScript, or brand new off-desktop prototyping environments. To enable novice programmers to incorporate gestures into their UI prototypes, we present a "$1 recognizer" that is easy, cheap, and usable almost anywhere in about 100 lines of code. In a study comparing our $1 recognizer, Dynamic Time Warping, and the Rubine classifier on user-supplied gestures, we found that $1 obtains over 97% accuracy with only 1 loaded template and 99% accuracy with 3+ loaded templates. These results were nearly identical to DTW and superior to Rubine. In addition, we found that medium-speed gestures, in which users balanced speed and accuracy, were recognized better than slow or fast gestures for all three recognizers. We also discuss the effect that the number of templates or training examples has on recognition, the score falloff along recognizers' N-best lists, and results for individual gestures. We include detailed pseudocode of the $1 recognizer to aid development, inspection, extension, and testing.

variable frame rate

In Proceedings of UIST 2009
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Activity analysis enabling real-time video communication on mobile phones for deaf users (p. 79-88)

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We describe our system called MobileASL for real-time video communication on the current U.S. mobile phone network. The goal of MobileASL is to enable Deaf people to communicate with Sign Language over mobile phones by compressing and transmitting sign language video in real-time on an off-the-shelf mobile phone, which has a weak processor, uses limited bandwidth, and has little battery capacity. We develop several H.264-compliant algorithms to save system resources while maintaining ASL intelligibility by focusing on the important segments of the video. We employ a dynamic skin-based region-of-interest (ROI) that encodes the skin at higher quality at the expense of the rest of the video. We also automatically recognize periods of signing versus not signing and raise and lower the frame rate accordingly, a technique we call variable frame rate (VFR).

We show that our variable frame rate technique results in a 47% gain in battery life on the phone, corresponding to an extra 68 minutes of talk time. We also evaluate our system in a user study. Participants fluent in ASL engage in unconstrained conversations over mobile phones in a laboratory setting. We find that the ROI increases intelligibility and decreases guessing. VFR increases the need for signs to be repeated and the number of conversational breakdowns, but does not affect the users' perception of adopting the technology. These results show that our sign language sensitive algorithms can save considerable resources without sacrificing intelligibility.