42411588
Computer vision issues during eye-in-hand robotic tasks
Our previous work has introduced the framework of controlled active vision that provides a bridge between computer vision and control theory. This paper presents some of the computer vision techniques that were employed in order to detect targets, automatically select features, measure feature displacements, and evaluate measurements during the various applications of the controlled active vision framework. We experimented with a lot of different techniques, but the most robust proved to be the sum-of-squared differences (SSD) optical flow technique. Search optimizations and dynamic pyramiding are proposed in order to provide real-time performance. In addition, several techniques for the evaluation of the measurements are presented. One important characteristic of these techniques is that they can also be used for the selection of features for tracking in conjunction with several numerical criteria that guarantee the robustness of the servoing. These techniques are important aspects of our work since they can be implemented either on-line or off-line. The paper concludes with results from the application of these techniques to real images.
5822992
Active Deformable Models Using Density Estimation
This paper introduces a new approach to active deformable models. The paper starts with a brief review of the relevant approaches. We then use the Expectation Maximization and Parzen Window techniques to develop a more robust formulation for pressure snakes. The generic nature of the proposed model allows it to perform well on complex colored images. We show, by several examples, the enhanced performance of the snake under the new formulation, compared to the performance of other known snake formulations.
6341521
Rethinking classical internal forces for active contour models
The classical active contour model has two basic internal forces: tension and curvature. These forces are included to provide cohe sion, equal control point spacing, and locally smooth shape. These classical internal forces have undesirable attributes that are in conflict with these original desired characteristics. Tension evenly spaces the control points, but also causes the models to collapse in weak image gradients. Curvature produces locally smooth curvature, but it does so by forcing the model toward a straight line. The paper returns to the original active contour model motivations to reformulate these internal forces. The desired properties are achieved without the introduction of unwanted model behavior A new spacing force and a new constant change in curvature force are introduced and their performance characteristics are discussed. The paper includes experimental results that demonstrate the efficacy and performance of the proposed reformulations.
16135450
Software Performance AntiPatterns; Common Performance Problems and their Solutions
A pattern is a common solution to a problem that occurs in many different contexts. Pat- terns capture expert knowledge about "best practices" in software design in a form that allows that knowledge to be reused and applied in the design of many different types of software. Antipatterns are conceptually similar to patterns in that they document recurring solutions to common design problems. They are known as antipatterns because their use (or misuse) produces negative consequences. Antipatterns document common mistakes made during software development as well as their solutions. While both patterns and antipatterns can be found in the literature, they typically do not explicitly consider performance consequences. This paper explores antipatterns from a performance perspective. We propose four new performance antipatterns that often occur in software systems.
4403848
A Critical Appraisal of the Box Counting Method to Assess the Fractal Dimension of Tree Crowns
In this paper, we study the application of the box counting method (BCM) to estimate the fractal dimension of 3D plant foliage. We use artificial crowns with known theoretical fractal dimension to characterize the accuracy of the BCM and we extend the approach to 3D digitized plants. In particular, errors are experimentally characterized for the estimated values of the fractal dimension. Results show that, with careful protocols, the estimated values are quite accurate. Several limits of the BCM are also analyzed in this context. This analysis is used to introduce a new estimator, derived from the BCM estimator, whose behavior is characterized.
6988052
QSEM: Quantitative Scalability Evaluation Method
While scalability is important to today's software applications, few organizations understand how to quantitatively evaluate their software's scalability. This paper describes the Quantitative Scalability Evaluation Method, QSEM. QSEM uses straightforward measurements to quantify the scalability of a software application. The results provide an understanding of the application's scalability that makes it possible to extrapolate behavior to larger configurations with confidence. The seven steps of the QSEM method are described and illustrated with a case study.
36985476
Who Wins on eBay: An Analysis of Bidders and Their Bid Behaviours
Online auctioning is one of the more successful business innovations on the Web. The auction format at eBay, the leading online auctioneer, has some unique characteristics including a fixed closing time for the bids and the use of a proxy bidding system that that is capable of acting as a bidder's agent. These features, coupled with third party products such as sniping software, have introduced novel bidder behaviours that may not occur in more traditional auction formats. In an attempt to study these behaviours, we collected and analysed data from over 11,000 eBay auctions. This paper presents the results of the analyses including descriptive information about the auctions and the classification of bids and bidders based on bid timing, frequency and strategy employed. The different types of bidders and their success rates offer insights into the nature of bidder participation in eBay auctions. In addition, chi‐square analyses reveal significant differences among the bidding strategies with respect to auc...
22904680
Software Performance Engineering Tutorial