42475732
An object-oriented approach to visual databases
As the demand for virtual reality systems increases, a new approach is needed to meet the following requirements: a world consists of a large number of objects; a camera is allowed to move and a world should be displayed in near real-time depending on the position of the camera as well as the angle of its lens; and minimum effort should be needed when objects are moving. We satisfy these requirements with the following: an object-oriented rendering approach is developed; and an approach based on spatial indexing (specifically R/sup +/-tree) is developed to manage operations on objects (i.e., retrieval, insertion and deletion) effectively.
28214269
Active rule processing in the BioCompose database
BioCompose is an object-relational database query tool that runs on top of any relational database and provides an intelligent and complete object-relational interface to the user. Unlike the traditional approach, which is completely table driven, queries in BioCompose are structured along the lines of natural language and sentences. In BioCompose, the database server continuously monitors the triggers and integrity constraints which are expressed as logical rules and are evaluated based on incoming events which include real time events, value events, transaction events, abstract events, and message events. The paper presents a novel approach that compiles triggers and integrity constraints into an asynchronous network to minimize the rule evaluation effort under different kinds of events.
42266951
TMO-structured cluster-based real-time management of location data on massive volume of moving items
A major challenge in the field of location based service (LBS) system engineering, is to establish a highly scalable system architecture which can be instantiated in moderate-size configurations handling thousands of moving items as well as in upper-end configurations handling millions of moving items. We are exploring an approach of using a cluster of database server nodes and effecting efficient distributed and parallel computing in both real-time update of location records of moving items and processing of location-related queries. The approach of developing efficient middleware which is layered on a cluster of nodes running commercial off-the-shelf database servers, has been adopted. The middleware design is substantially based on the TMO scheme for real-time distributed object programming and real-time distributed computing system design, which enables low-overhead coordination of distributed computations and highly abstract distributed programming styles.
207130153
A Software Test and Evaluation Environment Based on Longitudinal Database
To assure the quality of software by running test cases and evaluating the results is one of the difficult parts of the entire software development project. The difficulty usually comes from the lack of appropriate supporting tools and the complexity of the software. In the past ad hoc supporting tools were made for each project and test results were usually not used across projects. This conventional way of test and evaluation (T&E) is time consuming, and the most important decision "When is this software ready to ship?" is left to the engineers depending on their experiences. Our objective is to build a knowledge-based T&E environment such that tests cases, test results, object snapshots and other information are accumulated in a database. These longitudinal data can be automatically tracked and analyzed to provide decision support information. As a result, test results can be reviewed repeatedly and software quality can be assured by analyzing these data from various perspectives.
9564557
An Object-Oriented Approach to Shadow Generation in Computer Graphics
This paper presents an object-oriented shadow generation algorithm for a large number of convex polyhedra (objects) in a 3-D scene. In the past, the shadow volume binary space partitioning (SVBSP) tree algorithm is known to be efficient in a static environment in which the point light source can be changed. However, if a scene consists of many objects and each object consists of many polygons, the time complexity for generating and traversing an SVBSP tree increases rapidly because the SVBSP tree algorithm only deals with polygons which are components of objects. Furthermore, the SVBSP tree algorithm suffers from polygon-splitting problems resulting in a high cost as the number of polygons increases. Our approach is object-oriented in the sense that an object is used as the basic logical unit instead of polygons. In the preprocessing stage the object ordering for shadow generation is determined for all possible light source positions. At the run time, the shadow detection algorithm is executed, and if nec...
5688593
A Cluster-Based TMO-Structured Scalable Approach for Location Information Systems
Location-based service (LBS) systems have recently become a subject of active research and development. A key issue in such systems is efficient management of current and past location information of moving items. In the past two years, we have been establishing a new LBS system architecture, named the GALIS (Gracefully Aging Location Information System), which is based on the new approach of using a cluster of database server nodes and effecting efficient distributed and parallel computing in both real-time update of location records of moving items and processing of location-related queries. Each server node is dedicated to keeping records relevant to a different geographical zone and a different temporal zone. Each subsystem in GALIS is structured as a TMO network for the sake of easy analysis and expansion. A prototype implementation of GALIS has been realized only partially, and its full implementation is under way. In this paper, major features of GALIS are presented together with discussions on trade-off considerations which led to the adoption of those features. Issues remaining for further research are also briefly discussed.
6293093
Iterative Estimation of 3D Transformations for Object Alignment
An Iterative Estimation Algorithm (IEA) of 3D transformations between two objects is presented in this paper. Skeletons of the 3D objects are extracted using a fully parallel thinning technique, feature point pairs (land markers) are extracted from skeletons automatically with a heuristic rule, and a least squares method and an iterative approach are applied to estimate the 3D transformation matrix. The algorithm has three advantages. First of all, no initial transformation matrix is needed. Secondly, user interaction is not required for identifying the land markers. Thirdly, the time complexity of this algorithm is polynomial. Experiments show that this method works quite well with high accuracy when the translations and rotation angles are small, even when noise exists in the data.
12394125
Using compressed bytecode traces for slicing Java programs
Dynamic slicing is a well-known program debugging technique. Given a program P and input I, it finds all program statements which directly/indirectly affect the values of some variables' occurrences when P is executed with I. Dynamic slicing algorithms often proceed by traversing the execution trace of P produced by input I (or a dependence graph which captures control/data flow in the execution trace). Consequently, it is important to develop space efficient representations of the execution trace. In this paper, we use results from data compression to compactly represent bytecode traces of sequential Java programs. The major space savings come from the optimized representation of data (instruction) addresses used by memory reference (branch) bytecodes as operands. We give detailed experimental results on the space efficiency and time overheads for our compact trace representation. We then show how dynamic slicing algorithms can directly traverse our compact traces without resorting to costly decompression. We also develop an extension of dynamic slicing which allows us to explain omission errors (i.e. why some events did not happen during program execution).
29522196
On uniquely intersectable graphs
Abstract The concept of unique intersectability of a graph is introduced; this is related to the intersection number of a graph. The triangle-free condition is sufficient but not necessary for a graph to be uniquely intersectable. Other results related to the intersection number of a graph and its unique intersectability are established. Four families of graphs with triangles are shown to be uniquely intersectable.
33719933
Possibilistic C-Template Clustering and Its Application in Object Detection in Images
We present in this paper a new type of alternating-optimization based possibilistic c-shell clustering algorithm called possibilistic c-template (PCT). A template is represented by a set of line segments. A cluster prototype consists of a copy of the template after translation, scaling, and rotation transforms. This extends the capability of shell clustering beyond a few standard geometrical shapes that have been studied so far. We use a number of 2-dimensional data sets to illustrate the application of our algorithm in detecting generic template-based shapes in images. Techniques taken to relax the requirements of known number of clusters and good initialization are also described. Results for both synthetic and actual image data are presented.
15147164
Balanced incomplete designs for 3D perceptual quality estimation
Many factors, such as the number of vertices and the resolution of texture, can affect the display quality of 3D objects. When the resources of a graphics system are not sufficient to render the ideal image, degradation is inevitable. It is therefore important to study how individual factors affect the overall quality, and how the degradation can be controlled given limited resources. The essential factors determining the display quality are reviewed and a 3D perceptual estimation method is described. One of the major concerns in designing perceptual experiments is the large number of evaluations to be performed by judges, which results in fatigue and errors in judgement. To reduce judging fatigue and increase reliability of evaluations we propose using a statistical approach, following the design of experiments technique of balanced incomplete block design (BIBD). We develop models following BIBD for perceptual experiments and validate our model with experimental results. Even though the BIBD framework for perceptual evaluations is described in the context of 3D quality estimation, the approach can be used in other perceptual evaluation scenarios as well.