Collaborative access control is receiving growing attention in both military and commercial areas due to an urgent need to protect confidential resources and sensitive *** access control means that multiple subjects s...
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Collaborative access control is receiving growing attention in both military and commercial areas due to an urgent need to protect confidential resources and sensitive *** access control means that multiple subjects should participate to make access control decisions to prevent fraud or the abuse of *** approaches to access control cannot satisfy the requirements of collaborative access *** address this concern,we propose an authorization model for collaborative access *** central notions of the model are collaborative permission,collaboration constraint,and collaborative authorization policy,which make it possible to define the collaboration among multiple subjects involved in gaining a *** implementation architecture of the model is also ***,we present effective conflict detection and resolution methods for maintaining the consistency of collaborative authorization policies.
This paper attempts to discuss the evolution of semantic based image retrieval. The explosive growth of image data leads to the need of research and development of Image retrieval. Image retrieval researches are movin...
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SMS communication is gaining increasing popularity in people's daily life. Along with the growing number of times people sending and receiving SMSs every day, there are also increasing unwanted interruption to peo...
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In computergraphics one is often concerned with representing 3D objects on 2D displays, which provide often only a limited display field of view (DFOV) to the observer. Usually, planar geometric projections, in parti...
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This paper provides a classification of perceptual issues in augmented reality, created with a visual processing and interpretation pipeline in mind. We organize issues into ones related to the environment, capturing,...
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Light transport is often characterized within a high-dimensional space although practitioners have long known that it commonly behaves as a much lower-dimensional phenomenon. We study the effective dimension of light ...
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Physical characteristics and constraints of today's head-mounted displays (HMDs) often impair interaction in immersive virtual environments (VEs). For instance, due to the limited field of view (FOV) subtended by ...
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A five dimensional (5D) geospatial dataset consists of several multivariable 4D datasets, which are sequences of time-varying volumetric 3D geographical datasets. These datasets are typically very large in size and de...
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A five dimensional (5D) geospatial dataset consists of several multivariable 4D datasets, which are sequences of time-varying volumetric 3D geographical datasets. These datasets are typically very large in size and demand a great amount of resources for storage and transmission. In this paper, we present a lossy compression technique for 5D geospatial data as a whole, instead of applying 3D compression method on each 3D slice of the 5D dataset. Our lossy compression technique efficiently exploits spatial and temporal similarities between 2D data slices and 3D volumes in 4D oceanographic datasets. 5D-ODETLAP, which is an extension of, but essentially different from, the Laplacian partial differential equation, solves a sparse overdetermined system of equations to compute data at each point in (x,y,z,t,v) space from the data given at a representative set of points. 5D-ODETLAP is not restricted to certain types of datasets. For different datasets, it has the flexibility to approximate each one according to their respective data distributions by using suitable parameters. The final approximation is further compressed using Run Length Encoding. We use different datasets and metrics to test 5D-ODETLAP, and performance evaluations have shown that the proposed compression technique outperforms current 3D-SPIHT method on our selected datasets, from the World Ocean Atlas 2005. Having about the same mean percentage error, 5D-ODETLAP's compression result produces much smaller maximum error than 3D-SPIHT. A user-defined mean or maximum error can be set to obtain desired compression in the proposed method, while not in 3D-SPIHT.
In recent years, Geometric Algebra (GA) has become more and more popular in fields of science and engineering due to its potential for compact algorithms. However, the execution of GA algorithms and the related need f...
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ISBN:
(纸本)9788086943855
In recent years, Geometric Algebra (GA) has become more and more popular in fields of science and engineering due to its potential for compact algorithms. However, the execution of GA algorithms and the related need for high computational power is still the limiting factor for these algorithms to be used in practice. Therefore, it would be desirable to automatically detect parts that can be calculated in parallel by a software tool. In this paper, we present Gaalop 2.0, a Geometric Algebra Algorithm Compiler, which takes as input the description of a GA algorithm, symbolically optimizes the output multivectors and compiles the optimized code into a target language source file such as C++, for instance. For each output multivector the code for the different coefficients is generated, which is finally adjusted to contain only basic arithmetic operations instead. This allows the optimized output to be compiled for parallel computing platforms like FPGAs, for instance.
A new quality measure is proposed for evaluating the performance of segmentation algorithms. This discrepancy method is based on object-by-object comparison of a segmented image (machine segmentation) versus ground-tr...
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ISBN:
(纸本)9780889868243
A new quality measure is proposed for evaluating the performance of segmentation algorithms. This discrepancy method is based on object-by-object comparison of a segmented image (machine segmentation) versus ground-truth segmentation (reference image). The error measure we propose offers two main advantages compared to other quality measures. The first advantage to mention is the use of alternative methods in computing the distance from the contour of the segmented object to the reference one. This method takes into consideration the interior of the object and eliminates the inconveniences that appear in the case of the concave objects. The second improvement comes from adding a weighted shape fitting score: the score of the segmented contour is enhanced by a factor which indicates the similarity between these two curves.
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