The Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC) lattices have been analytically shown to be more efficient sampling lattices than the traditional Cartesian Cubic (CC) lattice, but there has been no estimate of their visual comparability. Two perceptual studies (each with N = 12 participants) compared the visual quality of images rendered from BCC and FCC lattices to images rendered from the CC lattice. Images were generated from two signals: the commonly used Marschner-Lobb synthetic function and a computed tomography scan of a fish tail. Observers found that BCC and FCC could produce images of comparable visual quality to CC, using 30-35 percent fewer samples. For the images used in our studies, the L(2) error metric shows high correlation with the judgement of human observers. Using the L(2) metric as a proxy, the results of the experiments appear to extend across a wide range of images and parameter choices.

We use a haptically enhanced mixing board with a video projector as an interface to various data visualization tasks. We report results of an expert review with four participants, qualitatively evaluating task), parallel coordinates interface (multi-dimensional combinato-rial search), and ExoVis (3D spatial navigation). Our investigation sought to determine the strengths of this physical input given its ca-pability to facilitate bimanual interaction, constraint maintenance, tight coupling of input and output, and other features. Participants generally had little difficulty with the mappings of parameters to sliders. The graspable sliders apparently reduced the mental exer-tion needed to acquire control, allowing participants to attend more directly to understanding the visualization. Participants often des-ignated specific roles for each hand, but only rarely moved both hands simultaneously.

We present a design space explorer for the space of experimental designs. For many design problems, design decisions are determined by the consequences of the design rather than its elemental parts. To support this need, the explorer is constructed to make the designer aware of design-level options, provide a structured context for design, and provide feedback on the consequences of design decisions. We argue that this approach encourages the designer to consider a wider variety of designs, which will lead to more effective designs overall. In a qualitative study, experiment designers using the explorer were found to consider a wider variety of designs and more designs overall than they reported considering in their normal practice.

This paper presents a user study of the visual quality of an imaging pipeline employing the optimal body-centered cubic (BCC) sampling lattice. We provide perceptual evidence supporting the theoretical expectation that sampling and reconstruction on the BCC lattice offer superior imaging quality over the traditionally popular Cartesian cubic (CC) sampling lattice. We asked 12 participants to choose the better of two images: one image rendered from data sampled on the CC lattice and one image that is rendered from data sampled on the BCC lattice. We used both synthetic and CT volumetric data, and confirm that the theoretical advantages of BCC sampling carry over to the perceived quality of rendered images. Using 25% to 35% fewer samples, BCC sampled data result in images that exhibit comparable visual quality to their CC counterparts.

Most users do not experience the same level of fluency in their interactions with computers that they do with physical objects in their daily life. We believe that much of this results from the limitations of unimodal interaction. Previous efforts in the haptics literature to remedy those limitations have been creative and numerous, but have failed to produce substantial improvements in human performance. This paper presents a new approach, whereby haptic interaction techniques are designed from scratch, in explicit consideration of the strengths and weaknesses of the haptic and motor systems. We introduce a haptic alternative to the tool palette, called Pokespace, which follows this approach. Two studies (6 and 12 participants) conducted with Pokespace found no performance improvement over a traditional interface, but showed that participants learned to use the interface proficiently after about 10 minutes, and could do so without visual attention. The studies also suggested several improvements to our design.

A high quality computer synthesis of an acoustic sound source does not necessarily yield a playable virtual musical instrument. A computer simulation of an acoustic musical instrument creates a disconnect between sound production and user input, and correspondingly, between hearing and feeling, in contrast to their interconnection in an acoustic instrument. This disconnect denies the user important haptic clues well known to help instrument control, impeding the user's ability to find, and remain inside, regions of playability. This research explores the addition of haptic feedback to a virtual reed model. In particular, we render the instrument's parameter space as a dynamic force field in order to support fine motor movements and, in turn, provide the user with cues regarding the instrument's oscillatory state and possible regions of playability. We then observe the effects that this additional feedback has on the user's ability to play the virtual instrument.

Two studies evaluated linear and hierarchy+elision small‐screen display formats for clinical reasoning tasks. A controlled, quantitative study with 28 medically naive participants using a task abstracted from clinical use of laboratory results found that both display formats supported rapid and accurate decision making. Distribution of the search targets significantly affected speed, with decisions in linear format made 13% faster (4.7 sec) when all targets could be viewed on a single screen than when targets required scrolling between several screens and in hierarchical format 15% faster (5.1 sec) when all the targets were confined within one category. Performance was equivalent regardless of the relative order of the target results and data in the laboratory report. In a qualitative study, 7 physicians used the displays to perform a realistic diagnosis. Physicians were comfortable with both display formats, but preference varied with clinical experience. The 5 less experienced clinicians favored hierarchy+elision, whereas the 2 highly experienced clinicians tended to prefer the linear display.

We describe a series of experiments that compare 2D displays, 3D displays, and combined 2D/3D displays (orientation icon, ExoVis, and clip planes) for relative position estimation, orientation, and volume of interest tasks. Our results indicate that 3D displays can be very effective for approximate navigation and relative positioning when appropriate cues, such as shadows, are present. However, 3D displays are not effective for precise navigation and positioning except possibly in specific circumstances, for instance, when good viewing angles or measurement tools are available. For precise tasks in other situations, orientation icon and ExoVis displays were better than strict 2D or 3D displays (displays consisting exclusively of 2D or 3D views). The combined displays had as good or better performance, inspired higher confidence, and allowed natural, integrated navigation. Clip plane displays were not effective for 3D orientation because users could not easily view more than one 2D slice at a time and had to frequently change the visibility of individual slices. Major factors contributing to display preference and usability were task characteristics, orientation cues, occlusion, and spatial proximity of views that were used together.

Displays combining both 2D and 3D views have been shown to support higher performance on certain visualization tasks. However, it is not clear how best to arrange a combination of 2D and 3D views spatially in a display. In this study, we analyzed the eyegaze strategies of participants using two arrangements of 2D and 3D views to estimate the relative position of objects in a 3D scene. Our results show that the 3D view was used significantly more often than individual 2D views in both displays, indicating the importance of the 3D view for successful task completion. However, viewing patterns were significantly different between the two displays: transitions through centrally-placed views were always more frequent, and users avoided saccades between views that were far apart. Although the change in viewing strategy did not result in significant performance differences, error analysis indicates that a 3D overview in the center may reduce the number of serious errors compared to a 3D overview placed off to the side.

We compare 2D/3D combination displays to displays with 2D and 3D views alone. Combination displays we consider are: orientation icon (i.e., side-by-side), in-place methods (e.g., clip planes), and a new method called ExoVis. We specifically analyze performance differences (i.e., time and accuracy) for 3D orientation and relative position tasks. Empirical results show that 3D displays are effective for approximate navigation and relative positioning whereas 2D/3D combination displays (orientation icon and ExoVis) are useful for precise orientation and position tasks. Combination 2D/3D displays had as good or better performance as 2D displays. Clip planes were not effective for a 3D orientation task, but may be useful when only one slice is needed.

Visual information is important in surgeons' manipulative performance especially in laparoscopic surgery where tactual feedback is less than in open surgery. The study of surgeons' eye movements is an innovative way of assessing skill, in that a comparison of the eye movement strategies between expert surgeons and novices may show important differences that could be used in training. We conducted a preliminary study comparing the eye movements of 5 experts and 5 novices performing a one-handed aiming task on a computer-based laparoscopic surgery simulator. The performance results showed that experts were quicker and generally committed fewer errors than novices. We investigated eye movements as a possible factor for experts performing better than novices. The results from eye gaze analysis showed that novices needed more visual feedback of the tool position to complete the task than did experts. In addition, the experts tended to maintain eye gaze on the target while manipulating the tool, whereas novices were more varied in their behaviours. For example, we found that on some trials, novices tracked the movement of the tool until it reached the target.

Originally designed as a messaging application, email is now used for a wide range of functions. Email clients however have not progressed correspondingly to support users with email management. This work describes the design of EzMail, an email visualization tool that runs in conjunction with an email client and creates a multi-view interface to assist with email management. Our primary focus is to group and visualize messages as components of threads to provide contextual information and conversational history. We have developed visualizations for individual messages, message properties, and messages in a thread. Message annotation is incorporated, along with a capability for replying simultaneously to several messages. A small user survey and a user study provided information regarding users' management of their messages and threads, and a comparative evaluation of EzMail with respect to Microsoft Outlook.

The IS0 9241, Part 9 Draft International Standard for testing computer pointing devices proposes an evaluation of performance and comfort. In this paper we evaluate the scientific validity and practicality of these dimensions for two pointing devices for laptop computers, a finger-controlled isometric joystick and a touchpad. Using a between-subjects design, evaluation of performance using the measure of throughput was done for one-direction and multi-directional pointing and selecting. Results show a significant difference in throughput for the multi-directional task, with the joystick 27% higher; results for the one-direction task were non-significant. After the experiment, participants rated the device for comfort, including operation, fatigue, and usability. The questionnaire showed no overall difference in the responses, and a significant statistical difference in only the question concerning force required to operate the device - the joystick requiring slightly more force. The paper concludes with a discussion of problems in implementing the IS0 standard and recommendations for improvement.

User interfaces for color selection consist of a visible screen representation, an input method, and the underlying conceptual organization of the color model. We report a two-way factorial, between-subjects variable experiment that tested the effect of high and low visual feedback interfaces on speed and accuracy of color matching for RGB and HSV color models. The only significant effect was improved accuracy due to increased visual feedback. Using color groups as a within-subjects variable, we found differences in performance of both speed and accuracy. We recommend that experimental tests adopt a color test set that does not show bias toward a particular model, but is based instead on a range of colors that would be most likely matched in practice by people using color selection software. We recomment the Macbeth Color Checker naturals, primaries, and grays. As a follow-up study, a qualitative case analysis of the way users navigated through the color space indicates that feedback helps users with limited knowledge of the model, allowing them to refine their match to a higher degree of accuracy. Users with very little or a lot of knowledge of the color model do not appear to be aided by increased feedback. In conclusion, we suggest that visual feedback and design of the interface may be a more important factor in improving the usability of a color selection interface than the particular color model used.

Article Do color models really make a difference? Share on Authors: Sarah Douglas Department of Computer Science, University of Oregon, Eugene, OR Department of Computer Science, University of Oregon, Eugene, ORView Profile , Ted Kirkpatrick Department of Computer Science, University of Oregon, Eugene, OR Department of Computer Science, University of Oregon, Eugene, ORView Profile Authors Info & Claims CHI '96: Proceedings of the SIGCHI Conference on Human Factors in Computing SystemsApril 1996 Pages 399–ff.https://doi.org/10.1145/238386.238585Online:13 April 1996Publication History 6citation1,086DownloadsMetricsTotal Citations6Total Downloads1,086Last 12 Months21Last 6 weeks3 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access