http://idea.library.drexel.edu/handle/1860/804 Search the Channel search http://idea.library.drexel.edu/simple-search http://idea.library.drexel.edu/handle/1860/2717 Title: The Athens affair <br/> <br/>Authors: Prevelakis, Vassilis; Spinellis, Diomidis http://idea.library.drexel.edu/handle/1860/2701 Title: Mixture of spherical distributions for single-view relighting <br/> <br/>Authors: Hara, Kenji; Nishino, Ko; Ikeuchi, Katsushi <br/> <br/>Abstract: Wepresent a method for simultaneously estimating the illumination of a scene and the reflectance property of an object from single view images—a single image or a small number of images taken from the same viewpoint.Weassume that the illumination consists of multiple point light sources, and the shape of the object is known. First, we represent the illumination on the surface of a unit sphere as a finite mixture of von Mises-Fisher distributions based on a novel spherical specular reflection model that well approximates the Torrance- Sparrow reflection model. Next, we estimate the parameters of this mixture model including the number of its component distributions and the standard deviation of them, which correspond to the number of light sources and the surface roughness, respectively. Finally, using these results as the initial estimates, we iteratively refine the estimates based on the original Torrance-Sparrow reflection model. The final estimates can be used to relight single-view images such as altering the intensities and directions of the individual light sources. The proposed method provides a unified framework based on directional statistics for simultaneously estimating the intensities and directions of an unknown number of light sources, as well as the specular reflection parameter of the object in the scene. http://idea.library.drexel.edu/handle/1860/2590 Title: Lane-change detection using a computational driver model <br/> <br/>Authors: Salvucci, Dario D.; Mandalia, Hiren M.; Kuge, Nobuyuki; Yamamura, Tomohiro <br/> <br/>Abstract: Objective: This paper introduces a robust, real-time system for detecting driver lane changes. Background: As intelligent transportation systems evolve to assist drivers in their intended behaviors, the systems have demonstrated a need for methods of inferring driver intentions and detecting intended maneuvers. Method: Using a “model tracing” methodology, our system simulates a set of possible driver intentions and their resulting behaviors using a simplification of a previously validated computational model of driver behavior. The system compares the model’s simulated behavior with a driver’s actual observed behavior and thus continually infers the driver’s unobservable intentions from her or his observable actions. Results: For data collected in a driving simulator, the system detects 82% of lane changes within 0.5 s of maneuver onset (assuming a 5% false alarm rate), 93% within 1 s, and 95% before the vehicle moves one fourth of the lane width laterally. For data collected from an instrumented vehicle, the system detects 61% within 0.5 s, 77% within 1 s, and 84% before the vehicle moves one-fourth of the lane width laterally. Conclusion: The model-tracing system is the first system to demonstrate high sample-by-sample accuracy at low false alarm rates as well as high accuracy over the course of a lane change with respect to time and lateral movement. Application: By providing robust realtime detection of driver lane changes, the system shows good promise for incorporation into the next generation of intelligent transportation systems. http://idea.library.drexel.edu/handle/1860/2575 Title: A probabilistic approach to source code authorship identification <br/> <br/>Authors: Kothari, Jay; Shevertalov, Maxim; Stehle, Edward; Mancoridis, Spiros <br/> <br/>Abstract: There exists a need for tools to help identify the authorship of source code. This includes situations in which the ownership of code is questionable, such as in plagiarism or intellectual property infringement disputes. Authorship identification can also be used to assist in the apprehension of the creators of malware. In this paper we present an approach to identifying the authors of source code. We begin by computing a set of metrics to build profiles for a population of known authors using code samples that are verified to be authentic. We then compute metrics on unidentified source code to determine the closest matching profile. We demonstrate our approach on a case study that involves two kinds of software: one based on open source developers working on various projects, and another based on students working on assignments with the same requirements. In our case study we are able to determine authorship with greater than 70% accuracy in choosing the single nearest match and greater than 90% accuracy in choosing the top three ordered nearest matches. http://idea.library.drexel.edu/handle/1860/2571 Title: Reducing program comprehension effort in evolving software by recognizing feature implementation convergence <br/> <br/>Authors: Kothari, Jay; Denton, Trip; Shokoufandeh, Ali; Mancoridis, Spiros <br/> <br/>Abstract: The implementations of software features evolve as an application matures. We define a measure of feature implementation overlap that determines how similar features are in their execution by examining their call graphs. We consider how this measure changes over time, and evaluate the hypothesis that over time and subsequent versions of a software application, the implementations of semantically similar features converge. As the features of an application converge in their implementation, we are able to more effectively determine groups of semantically similar features and to reduce the cost of program comprehension by selecting few key features that give an overview of the system. We present a case study analyzing the features of the Jext, Firefox, and Gaim software systems to support our hypothesis. http://idea.library.drexel.edu/handle/1860/2569 Title: On computing the canonical features of software systems <br/> <br/>Authors: Kothari, Jay; Denton, Trip; Mancoridis, Spiros; Shokoufandeh, Ali <br/> <br/>Abstract: Software applications typically have many features that vary in their similarity. We define a measurement of similarity between pairs of features based on their underlying implementations and use this measurement to compute a set of canonical features. The Canonical Features Set (CFS) consists of a small number of features that are as dissimilar as possible to each other, yet are most representative of the features that are not in the CFS. The members of the CFS are distinguishing features and understanding their implementation provides the engineer with an overview of the system undergoing scrutiny. The members of the CFS can also be used as cluster centroids to partition the entire set of features. Partitioning the set of features can simplify the understanding of large and complex software systems. Additionally, when a specific feature must undergo maintenance, it is helpful to know which features are most closely related to it. We demonstrate the utility of our method through the analysis of the Jext, Firefox, and Gaim software systems. http://idea.library.drexel.edu/handle/1860/2546 Title: Guest editors’ introduction to the special section from the international conference on software maintenance and evolution <br/> <br/>Authors: Binkley, David; Koschke, Rainer; Mancoridis, Spiros http://idea.library.drexel.edu/handle/1860/2545 Title: An evolutionary approach to software modularity analysis <br/> <br/>Authors: Huynh, Sunny; Cai, Yuanfang <br/> <br/>Abstract: Modularity determines software quality in terms of evolveability, changeability, maintainability, etc. and a module could be a vertical slicing through source code directory structure or class boundary. Given a modular- ized design, we need to determine whether its implementa- tion realizes the designed modularity. Manually comparing source code modular structure with abstracted design mod- ular structure is tedious and error-prone. In this paper, we present an automated approach to check the conformance of source code modularity to the designed modularity. Our approach uses design structure matrices (DSMs) as a uniform representation; it uses existing tools to automatically derive DSMs from the source code and de- sign, and uses a genetic algorithm to automatically cluster DSMs and check the conformance. We applied our approach to a small canonical software system as a proof of concept experiment. The results sup- ported our hypothesis that it is possible to check the con- formance between source code structure and design struc- ture automatically, and this approach has the potential to be scaled for use in large software systems. http://idea.library.drexel.edu/handle/1860/2541 Title: Performance analysis of a family of WHT algorithms <br/> <br/>Authors: Andrews, Michael; Johnson, Jeremy <br/> <br/>Abstract: This paper explores the correlation of instruction counts and cache misses to runtime performance for a large family of divide and conquer algorithms to compute the Walsh–Hadamard transform (WHT). Previous work showed how to compute instruction counts and cache misses from a high–level description of the algorithm and proved theoretical results about their minimum, maximum, mean, and distribution. While the models themselves do not accurately predict performance, it is shown that they are statistically correlated to performance and thus can be used to prune the search space for fast implementations. When the size of the transform fits in cache the instruction count itself is used; however, when the transform no longer fits in cache, a linear combination of instruction counts and cache misses is used. Thus for small transforms it is safe to ignore algorithms which have a high instruction count and for large transforms it is safe to ignore algorithms with a high value in the combined instruction count/cache miss model. Since the models can be computed from a high–level description of the algorithms, they can be obtained without runtime measurement and the previous theoretical results on the models can be applied to limit empirical search. http://idea.library.drexel.edu/handle/1860/1739 Title: Contour-based surface reconstruction using MPU implicit models <br/> <br/>Authors: Braude, Ilya; Marker, Jeffrey; Museth, Ken; Nissanov, Jonathan; Breen, David E. <br/> <br/>Abstract: This paper presents a technique for creating a smooth, closed surface from a set of 2D contours, which have been extracted from a 3D scan. The technique interprets the pixels that make up the contours as points in R3 and employs Multi-level Partition of Unity (MPU) implicit models to create a surface that approximately fits to the 3D points. Since MPU implicit models additionally require surface normal information at each point, an algorithm that estimates normals from the contour data is also described. Contour data frequently contains noise from the scanning and delineation process. MPU implicit models provide a superior approach to the problem of contour-based surface reconstruction, especially in the presence of noise, because they are based on adaptive implicit functions that locally approximate the points within a controllable error bound.We demonstrate the effectiveness of our technique with a number of example datasets, providing images and error statistics generated from our results.