David Ahlström

The Video Browser Showdown: a live evaluation of interactive video search tools

The Video Browser Showdown evaluates the performance of exploratory video search tools on a common data set in a common environment and in presence of the audience. The main goal of this competition is to enable researchers in the field of interactive video search to directly compare their tools at work. In this paper, we present results from the second Video Browser Showdown (VBS2013) and describe and evaluate the tools of all participating teams in detail. The evaluation results give insights on how exploratory video search tools are used and how they perform in direct comparison. Moreover, we compare the achieved performance to results from another user study where 16 participants employed a standard video player to complete the same tasks as performed in VBS2013. This comparison shows that the sophisticated tools enable better performance in general, but for some tasks common video players provide similar performance and could even outperform the expert tools. Our results highlight the need for further improvement of professional tools for interactive search in videos.

Ad-binning: leveraging around device space for storing, browsing and retrieving mobile device content

Exploring information content on mobile devices can be tedious and time consuming. We present Around-Device Binning, or AD-Binning, a novel mobile user interface that allows users to off-load mobile content in the space around the device. We informed our implementation of AD-Binning by exploring various design factors, such as the minimum around-device target size, suitable item selection methods, and techniques for placing content in off-screen space. In a task requiring exploration, we find that AD-Binning improves browsing efficiency by avoiding the minute selection and flicking mechanisms needed for on-screen interaction. We conclude with design guidelines for off screen content storage and browsing.

Studying spatial memory and map navigation performance on projector phones with peephole interaction

Smartphones are useful personal assistants and omnipresent communication devices. However, collaboration is not among their strengths. With the advent of embedded projectors this might change. We conducted a study with 56 participants to find out if map navigation and spatial memory performance among users and observers can be improved by using a projector phone with a peephole interface instead of a smartphone with its touchscreen interface. Our results show that users performed map navigation equally well on both interfaces. Spatial memory performance, however, was 41% better for projector phone users. Moreover, observers of the map navigation on the projector phone were 25% more accurate when asked to recall locations of points of interest after they watched a user performing map navigation.

Why it's quick to be square: modelling new and existing hierarchical menu designs

We consider different hierarchical menu and toolbar-like interface designs from a theoretical perspective and show how a model based on visual search time, pointing time, decision time and expertise development can assist in understanding and predicting interaction performance. Three hierarchical menus designs are modelled -- a traditional pull-down menu, a pie menu and a novel Square Menu with its items arranged in a grid -- and the predictions are validated in an empirical study. The model correctly predicts the relative performance of the designs -- both the eventual dominance of Square Menus compared to traditional and pie designs and a performance crossover as users gain experience. Our work shows the value of modelling in HCI design, provides new insights about performance with different hierarchical menu designs, and demonstrates a new high-performance menu type.

Improving Window Switching Interfaces

Switching between windows on a computer is a frequent activity, but current switching mechanisms make it difficult to find items. We carried out a longitudinal study that recorded actual window switching behaviour. We found that window revisitation is very common, and that people spend most time working with a small set of windows and applications. We identify two design principles from these observations. First, spatial constancy in the layout of items in a switching interface can aid memorability and support revisitation. Second, gradually adjusting the size of application and window zones in a switcher can improve visibility and targeting for frequently-used items. We carried out two studies to confirm the value of these design ideas. The first showed that spatially stable layouts are significantly faster than the commonly-used recency layout. The second showed that gradual adjustments to accommodate new applications and windows do not reduce performance.

A user study on image browsing on touchscreens

Default image browsing interfaces on touch-based mobile devices provide limited support for image search tasks. To facilitate fast and convenient searches we propose an alternative interface that takes advantage of 3D graphics and arranges images on a rotatable globe according to color similarity. In a user study we compare the new design to the iPads image browser. Results collected from 24 participants show that for color-sorted image collections the globe can reduce search time by 23% without causing more errors and that it is perceived as being fun to use and preferred over the standard browsing interface by 70% of the participants.

3-D Interfaces to Improve the Performance of Visual Known-Item Search

Most interfaces in the field of image and video search use a two-dimensional grid interface, which presents image thumbnails in a left-to-right arrangement that can be browsed from top to bottom. This grid interface, however, has several drawbacks that become particularly apparent when performing interactive search tasks for target items in large collections of images or videos. Therefore, we propose to use 3-D interfaces as an alternative to the grid interface for interactive known-item search in visual data as they can partially overcome these drawbacks. In this paper, we first summarize our ideas and discuss design aspects of a 3-D ring and a 3-D globe interface. Next, we present results from four different user studies, where we evaluated the performance of these interfaces for known-item search tasks in image collections. Our results from these studies show that the proposed 3-D interfaces allow for significantly faster visual target search on desktop computers with mouse interaction as well as on tablet devices. The interfaces also achieve better subjective ratings. However, our evaluation also shows that on smartphones with 3.5-in screens an improvement over the grid interface in terms of visual search time is only possible in collections with more than 200 images.

Characterizing user performance with assisted direct off-screen pointing

The limited viewport size of mobile devices requires that users continuously acquire information that lies beyond the edge of the screen. Recent hardware solutions are capable of continually tracking a users finger around the device. This has created new opportunities for interactive solutions, such as direct off-screen pointing: the ability to directly point at objects that are outside the viewport. We empirically characterize user performance with direct off-screen pointing when assisted by target cues. We predict time and accuracy outcomes for direct off-screen pointing with existing and derived models. We validate the models with good results (R2 ≥ 0.9) and reveal that direct off-screen pointing takes up to four times longer than pointing at visible targets, depending on the desired accuracy tradeoff. Pointing accuracy degrades logarithmically with target distance. We discuss design implications in the context of several real-world applications.

Using a 3D cylindrical interface for image browsing to improve visual search performance

In this paper we evaluate a 3D cylindrical interface that arranges image thumbnails by visual similarity for the purpose of image browsing. Through a user study we compare the performance of this interface to the performance of a common scrollable 2D list of thumbnails in a grid arrangement. Our evaluation shows that the 3D Cylinder interface enables significantly faster visual search and is the preferred search interface for the majority of tested users.

Interactive Evaluation of Video Browsing Tools

The Video Browser Showdown (VBS) is a live competition for evaluating video browsing tools regarding their efficiency at known-item search (KIS) tasks. The first VBS was held at MMM 2012 with eight teams working on 14 tasks, of which eight were completed by expert users and six by novices. We describe the details of the competition, analyze results regarding the performance of tools, the differences between the tasks and the nature of the false submissions.