A distance volume is a volume dataset where the value stored at each voxel is the shortest distance to the surface of the object being represented by the volume. Distance volumes are a useful representation in a num-b...
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(纸本)1581131054
A distance volume is a volume dataset where the value stored at each voxel is the shortest distance to the surface of the object being represented by the volume. Distance volumes are a useful representation in a num-berof computergraphics applications. In this paperwe present a technique for generating a distance volume with sub-voxel accuracy from one type of geometric model, a Constructive Solid Geometry (CSG) model consisting of superellipsoid primitives. The distance volume is generated in a two step process. The first step calculates the shortest distance to the CSG model at a set of points within a narrow band around the evaluated surface. Additionally, a second set of points, labeled the zero set, which lies on the CSG model's surface are computed. A point in the zero set is associated with each point in the narrow band. Once the narrow band and zero set are calculated, a Fast Marching Method is employed to propagate the shortest distance and closest point information out to the remaining voxels in the volume. Our technique has been used to scan convert a number of CSG models, producing distance volumes which have been utilized in a variety of computergraphics applications, e.g. CSG surface evaluation, offset surface generation, and 3-D model morphing. Copyright 1998 IEEE.
Introducing seemingly autonomous virtual beings into virtual environments to co-habit and collaborate with us is a continuous challenge and source of interest. Latest proof of human excitement for virtual life is the ...
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Introducing seemingly autonomous virtual beings into virtual environments to co-habit and collaborate with us is a continuous challenge and source of interest. Latest proof of human excitement for virtual life is the current worldwide craze for electronic pets that must be fed and cared for lest they develop a bad character or die. Even more interesting is the inclusion of autonomous actors in networked collaborative virtual environments (NCVEs). They provide a meeting place for people from different geographical locations and virtual beings. In NCVEs one doesn't see correspondents, only their graphical representations in the virtual world, which is the same as for the virtual ones-therefore the communication with virtual beings can come naturally. There is no single solution to the simulation of autonomous behavior. This is an ongoing research topic. Therefore it is interesting to provide an open NCVE system for easy interfacing with various implementations of autonomous behavior. In this way, the system can serve as an application platform with existing algorithms, as well as a research testbed for new autonomous behavior algorithms. The paper studies the requirements for such an open interface and, based on this study, presents an implementation within the Virtual Life Network (VLNET) system. Results are presented in terms of two case studies. A simple one implementing a dumb servant character and a more complex one connecting VLNET with the autonomous agent program Eliza (Weizenbaum, 1966).
Melanoma, one of the most aggressive types of cancer, can be healed, if recognized in early stages. In order to automate the early recognition of skin cancer; a system that analyses digital epiluminescence microscopic...
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Melanoma, one of the most aggressive types of cancer, can be healed, if recognized in early stages. In order to automate the early recognition of skin cancer; a system that analyses digital epiluminescence microscopic images is used. After segmentation, 33 features representing shape and radiometric properties are calculated. In the paper the quality of the features is evaluated by applying several feature selection methods. The results show that with each selection method the feature set can be reduced to dimension four with nearly no loss of information. Results with classification rates of up to 75% are achieved and relations between selected features and medical criteria are observed.
Accurate localization and tracking of facial features are crucial for developing high quality model-based coding (MPEG-4) systems. For teleconferencing applications at very low bit rates, it is necessary to track eye ...
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Accurate localization and tracking of facial features are crucial for developing high quality model-based coding (MPEG-4) systems. For teleconferencing applications at very low bit rates, it is necessary to track eye and lip movements accurately over time. These movements can be coded and transmitted to a remote site, where animation techniques can be used to synthesize facial movements on a model of a face. In this paper we describe and simple heuristics which are effective in improving the results of well-known facial feature detection and tracking algorithms. Animation models are also presented, along with experimental results to demonstrate the system being developed. We focus our discussion only on the detection, tracking and modeling of eye movements.
The paper introduces a new approach to simulate physical systems by asynchronous numerical integration: different bodies are moved with different stepsizes, but the whole system evolves within a single time frame. The...
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The paper introduces a new approach to simulate physical systems by asynchronous numerical integration: different bodies are moved with different stepsizes, but the whole system evolves within a single time frame. The approach ensures that interacting bodies are synchronized, but independent bodies are allowed to move independently. Particle system simulations show significant gain in performance when compared to the conventional, synchronous approach.
This paper describes how the concept of imposing geometric constraints by minimizing cost functions may be used and extended to accomplish a variety of animated modelling tasks for computergraphics. In this approach ...
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This paper presents an algorithm for solving the complex and critical problem of bending sequence in sheet metal manufacturing. Finding the bending sequence and required tool assignment presents a large combinatorial ...
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This paper presents an algorithm for solving the complex and critical problem of bending sequence in sheet metal manufacturing. Finding the bending sequence and required tool assignment presents a large combinatorial problem which is impossible to solve optimally for practical applications within a reasonable period of time. The paper presents a two-stage algorithm. The first stage finds a feasible solution based upon collision avoidance heuristics. The second stage rapidly seeks an alternative feasible sequence with a lower cost without exceeding time limitations. The algorithm is very practical because it reaches a low-cost solution quickly within computer memory limitations. In this paper, the problem is defined, the approach is presented formally, and finally, the power of the algorithm is demonstrated by solving bending sequences for real products.
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