1963845
Testbed evaluation of navigation and text display techniques in an information-rich virtual environment
The fundamental question for an information-rich virtual environment is how to access and display abstract information. We investigated two existing navigation techniques: hand-centered object manipulation extending ray-casting (HOMER) and go-go navigation, and two text layout techniques: within-the-world display (WWD) and heads-up display (HUD). Four search tasks were performed to measure participants' performance in a densely packed environment. HUD enabled significantly better performance than WWD and the go-go technique enabled better performance than the HOMER technique for most of the tasks. We found that using HOMER navigation combined with the WWD technique was significantly worse than other combinations for difficult naive search tasks. Users also preferred the combination of go-go and HUD for all tasks.
16627993
Increased display size and resolution improve task performance in Information-Rich Virtual Environments
Physically large-size high-resolution displays have been widely applied in various fields. There is a lack of research, however, that demonstrates empirically how users benefit from the increased size and resolution afforded by emerging technologies. We designed a controlled experiment to evaluate the individual and combined effects of display size and resolution on task performance in an Information-Rich Virtual Environment (IRVE). We also explored how a wayfinding aid would facilitate spatial information acquisition and mental map construction when users worked with various displays. We found that users were most effective at performing IRVE search and comparison tasks on large high-resolution displays. In addition, users working with large displays became less reliant on wayfinding aids to form spatial knowledge. We discuss the impact of these results on the design and presentation of IRVEs, the choice of displays for particular applications, and future work to extend our findings.
27797614
Interacting with Visible Human data using an ImmersaDesk
Interaction with medical volume data has often been difficult, due to the large memory and computational power required. By taking advantage of current high-end graphics hardware, we have developed a volumetric virtual environment that provides the ability to help people interact with the volumetric Visible Human data set. The application enables the user to explore the interior of a virtual human body in a natural and intuitive way.
208047947
New Directions in 3D User Interfaces
Three-dimensional user interfaces (3D UIs) support user tasks in many non-traditional interactive systems such as virtual environments and augmented reality. Although 3D UI researchers have been successful in identifying basic user tasks and interaction metaphors, evaluating the usability of 3D interaction techniques, and improving the usability of many applications, 3D UI research now stands at a crossroads. Very few fundamentally new techniques and metaphors for 3D interaction have been discovered in recent years, yet the usability of 3D UIs in many real-world applications is still not at a desirable level. What directions should 3D UI researchers next explore to improve this situation? In this paper, we make some observations about the history of 3D UIs and the current state-of-the-art. Using this evidence, in addition to our own experience, we argue that 3D UI researchers should approach this problem using some new research approaches, which cluster around the concepts of specificity, flavors, implementation, and emerging technologies. We illustrate and discuss some of these new directions using case studies of research projects undertaken in our group. These explorations indicate the promise of these directions for further increasing our understanding of 3D interaction and 3D UI design, and for ensuring the usability of 3D UIs in future applications.
3048500
Design and evaluation of alternative selection placement strategies in optimizing continuous queries
We design and evaluate alternative selection placement strategies for optimizing a very large number of continuous queries in an Internet environment. Two grouping strategies, PushDown and PullUp, in which selections are either pushed below, or pulled above, joins are proposed and investigated. While our earlier research has demonstrated that the incremental group optimization can significantly outperform an ungrouped approach, the results from the paper show that different incremental group optimization strategies can have significantly different performance characteristics. Surprisingly, in our studies, PullUp, in which selections are pulled above joins, is often better and achieves an average 10 fold performance improvement over PushDown (occasionally 100 times faster). Furthermore, a revised algorithm of PullUp, termed filtered PullUp is proposed that is able to further reduce the cost of PullUp by 75% when the union of the selection predicates is selective. Detailed cost models, which consider several special parameters, including (1) characteristics of queries to be grouped, and (2) characteristics of data changes, are presented. Preliminary experiments using an implementation of both strategies show that our models are fairly accurate in predicting the results obtained from the implementation of these techniques in the Niagara system.
6192242
Computing Maximum-Scoring Segments in Almost Linear Time
Given a sequence, the problem studied in this paper is to find a set of k disjoint continuous subsequences such that the total sum of all elements in the set is maximized. This problem arises naturally in the analysis of DNA sequences. The previous best known algorithm requires Θ(n log n) time in the worst case. For a given sequence of length n, we present an almost linear-time algorithm for this problem. Our algorithm uses a disjoint-set data structure and requires O(nα(n, n)) time in the worst case, where α(n, n) is the inverse Ackermann function.
14245135
Automatic Correlation and Calibration of Noisy Sensor Readings Using Elite Genetic Algorithms
This paper explores an image processing application of optimization techniques which entails interpreting noisy sensor data. The application is a generalization of image correlation; we attempt to find the optimal gruence which matches two overlapping gray scale images corrupted with noise. Both tabu search and genetic algorithms are used to find the parameters which match the two images. A genetic algorithm approach using an elitist reproduction scheme is found to provide significantly superior results.
2164421
Generating a configuration space representation for assembly tasks from demonstration
Removing suboptimal actions that can exist in a demonstration is a key problem to be solved in robot programming by demonstration. In this paper we present the first step of an approach for solving this problem. We present how the configuration space (C-space) of a task can be derived from demonstration. A demonstration traces out paths on a number of C-surfaces in C-space. The idea is to use statistical regression analysis on data from these paths to determine the unknown equation parameters of a C-surface. Experimental results show the validity of the approach. Accurate parameter estimates were obtained so long as a sufficiently rich set of demonstrated paths existed on the C-surface. The approach has the advantage that it tends to provide accurate parameter estimates for C-surfaces where they were most needed; that is, for C-surfaces (i) critical to task completion, and (ii) whose paths contained suboptimal actions.
27587317
An executable specification language for specification understanding in object-oriented specification reuse
System analysis time can be reduced through specification reuse which, however, requires specification understanding. This paper presents an object-oriented executable specification language which reduces understanding time through executing specifications. In addition to being executable, the specification language hides as many classes as possible within subsystems, and explicitly specifies relationships between specification components. This facilitates specification modification. Moreover, the language explicitly specifies interface parameters of specification components. This facilitates specification composition.