A description method for arbitrary two dimensional shapes is proposed in this paper. When a 2D shape is given as a silhouette, its structure is automatically approximated by the use of a set of rectangles by the propo...
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A description method for arbitrary two dimensional shapes is proposed in this paper. When a 2D shape is given as a silhouette, its structure is automatically approximated by the use of a set of rectangles by the proposed method. Sizes, positions and rotational angles of the rectangles which approximate adequately the given 2D shape are searched by a genetic algorithm; GA. In our coding of GA, a chromosome of each individual is a bit string corresponding to parameter sets of several rectangles. Through a generation iteration, accuracy of approximation of the given 2D shape is improved. The total number of rectangles to be used for description is assumed to be given before shape description. By changing the total number of rectangles, hierarchical description of given 2D shapes is achieved. This method can be applied to shape description and object recognition in the field of computer vision and to abstraction of 2D shapes in the field of artistic applications by the use of computers.
Collision detection tests between objects dominate run time simulation of rigid body animation. Traditionally, hierarchical bounding box tests are used to minimize collision detection time. But the bounding boxes do n...
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Collision detection tests between objects dominate run time simulation of rigid body animation. Traditionally, hierarchical bounding box tests are used to minimize collision detection time. But the bounding boxes do not take shapes of the objects into account which results in a large number of collision detection tests. We propose an adaptive spatial subdivision of the object space based on octree structure to rectify this problem. We also present a technique for efficiently updating this structure periodically during the simulation.
Visualization and animation tools may become extremely important aids in the understanding, verification, and performance tuning of parallel computations. Presently, however, the use of visualization has had only a li...
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Visualization and animation tools may become extremely important aids in the understanding, verification, and performance tuning of parallel computations. Presently, however, the use of visualization has had only a limited use for enhancing parallel computation. We hypothesize that one of the primary reasons for the limited use of visualization tools in parallel program development is the difficulty of acquiring the information necessary to drive the visual display. Our approach to this impediment focuses on integrating visualization support directly into a distributed computing system. Central to this integration is the addition of a logical clock that prevents the timestamps of events from violating causality. The implementation requires the "piggybacking" of a negligible amount of extra header information on system messages and the impact on performance is minimal. This results in a system that produces useful visualizations with no extra effort required by the applications programmer. Also integrated into the distributed system is support which simplifies the creation of programmer-defined, application-specific visualizations, unique to each new parallel program developed.
The process of converting a given design into the form of a rawstock minus a series of machining features is known as machining-features extraction. One step towards automatic machining-features extraction is the extr...
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The process of converting a given design into the form of a rawstock minus a series of machining features is known as machining-features extraction. One step towards automatic machining-features extraction is the extraction of machining regions. The paper is concerned with the extraction of machining regions from the constructive-solid-geometry representation of a given object. The proposed method for the extraction of machining regions is based on manipulating the original CSG tree, representing the object, evaluating the various machining regions by using octrees, and pruning the CSG tree accordingly. If necessary, an additional stage of compacting follows. As a result, each machining region is represented by a compact CSG tree offering the following advantages. The CSG tree to be analysed is reduced in size, and thus the problem of machining-features extraction is simplified. The information is compact and concise. Moreover, no information is lost (CSG representation is kept rather than boundary representation), and the designer's intensions are conveyed to the process planner more clearly. In the special case in which the machining regions are identical to machining features, the method does offer the automatic extraction of machining features. In addition, the nesting level of the various machining regions is determined when needed.
The scope of this paper is to propose a system for the automatic derivation of a human curved walking trajectory from the analysis provided by its synthetic vision module. The study context is a planar environment wit...
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The scope of this paper is to propose a system for the automatic derivation of a human curved walking trajectory from the analysis provided by its synthetic vision module. The study context is a planar environment wit...
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The scope of this paper is to propose a system for the automatic derivation of a human curved walking trajectory from the analysis provided by its synthetic vision module. The study context is a planar environment with still and sparse foothold locations. A general methodology associates the two low-level modules of vision and walking with a planification module which establishes the middle term path from the knowledge of the visualized environment. The planification is made under the constraint of minimizing the distance, the speed variation and the curvature cost. Moreover, the planification may trigger the alternate walking motion whenever the decreasing in curvature cost is higher than the associated increasing in speed variation cost due to the corresponding halt and restart. Finally, the characteristic of the next step location is derived in the context of a constant velocity walking motion along a circular trajectory.< >
We describe a system for semiautomatically extracting 3-D object models from raw, uncalibrated video. The system utilizes a recursive estimator to accurately recover camera motion, point-wise structure, and camera foc...
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We describe a system for semiautomatically extracting 3-D object models from raw, uncalibrated video. The system utilizes a recursive estimator to accurately recover camera motion, point-wise structure, and camera focal length. Recovered 3-D points are used to compute a piecewise-smooth surface model for the object. Recovered motion and camera geometry are then used along with the original video to texture map the surfaces. We describe extensions to our previously-reported geometry estimation formulation that incorporate focal length estimation and other improvements, so that accurate estimates of structure and camera motion can be recovered from uncalibrated video cameras. We also discuss the buildup of texture maps from sequences of images, which is important in producing realistic looking models. Examples demonstrate generation of a realistic 3-D texture mapped model from a video sequence, the post-production manipulation of video, and the combination of computergraphics models with video.< >
As algorithm animation systems become more widely available and easy to use, instructors will have the opportunity to utilize these systems to assist their teaching. Although algorithm animation systems have generated...
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As algorithm animation systems become more widely available and easy to use, instructors will have the opportunity to utilize these systems to assist their teaching. Although algorithm animation systems have generated excitement and interest in both teachers and students, little empirical evidence exists to promote their use. This article describes a study involving the use of algorithm animations in classroom and laboratory settings. Results indicated that allowing students to create their own examples in a laboratory session led to higher accuracy on a post-test examination of understanding as compared to students who viewed prepared examples or no laboratory examples.< >
作者：
ROSENBAUM, J[&lowast]Jan Rosenbaum has worked in the imaging industry for 30 years
first as a newspaper photographer and assistant professor of photography then as a camera designer and image quality specialist in the medical and computer graphics industries. He holds a B.F.A. in art from Wayne State University an M.F.A. in photography from Cranbrook Academy of Art an M.S. in imaging and photographic science from Rochester Institute of Technology and an M.S. in management of technology from Polytechnic University of New York. Until recently he was head of the optical and color science group at a division of Agfa-Gevaert.
The medical imaging industry offers an example of what can happen when an industry ignores threats from new technologies and fails to respond to a change in the paradigm upon which it is based. The lessons learned fro...
The medical imaging industry offers an example of what can happen when an industry ignores threats from new technologies and fails to respond to a change in the paradigm upon which it is based. The lessons learned from these basic errors in management may help those in other industries that operate at technology's edge to avoid obsolescence. The company discussed is, or was, real. As of summer, 1993, the last remaining vestige of the company was sold off to a small group of employees and their backers. The number of employees, once 900, is now fewer than 100. Most of them are looking for a way to stay in business.
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