Visualization of very large digital elevation models plays an important role in many applications ranging from computer games to professional Geographic Information System (GIS). However, the size of terrain datasets ...
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Visualization of very large digital elevation models plays an important role in many applications ranging from computer games to professional Geographic Information System (GIS). However, the size of terrain datasets is much larger than the capacity of main memory, which brings up serious challenges for the interactive visualization of massive terrain. In this paper, an effective visualization method for large-scale terrain is proposed. In preprecessing stage, the full resolution terrain dataset is divided into several uniform blocks. For each block, a LOD hierarchy, which contains different resolution of elevation data, is constructed based on quadtree-split. In order to save the external memory, a non-redundant storage method is put forward. Different from the traditional pyramid model, we stored only the newly added vertices in each level. The data quantity during real-time rendering decreased effectively due to the sight-line-dependent screen error computation, view frustum culling and detailed culling scheme. To ensure the continuity of navigation, a pre-loading scheme, which based on the view frustum extension, is presented and implemented. Experiments show that compared with traditional methods, our method has reduced the external memory cost by 60% and achieved good visual effect with high rendering speed.
The digital creation of cloud is important for many applications in computer graphics, including outdoor simulations and the digital rendering of atmospheric effects. Unfortunately, it is still difficult to simulate r...
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The digital creation of cloud is important for many applications in computer graphics, including outdoor simulations and the digital rendering of atmospheric effects. Unfortunately, it is still difficult to simulate realistic cloud with interactive frame rates due to its peculiar microstructures and complex physical process of formation. Realistic simulation of cloud turns to be one of the most challenging topics in computer graphics. In this paper, we present a method for simulating 3D cloud. The Coupled Map Lattice (CML) is adopted for the modeling of cloud, and the simulation of light scattering in clouds is achieved by using a series of spherical harmonics and spherical harmonic coefficients that represent incident-light distribution. A frequency domain volume-rendering algorithm combined with spherical harmonics is applied to implement fast rendering of cloud scenes. Experiments demonstrate that our method facilitates computing efficiency, while yielding realistic visual quality.
Grass animation plays an important role in various applications, such as virtual reality, computer games and special effects of movies. In recent years, varieties of approaches have been proposed to simulate the inter...
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Grass animation plays an important role in various applications, such as virtual reality, computer games and special effects of movies. In recent years, varieties of approaches have been proposed to simulate the interaction between grass and the wind field. However, simulation of grass-object interaction is seldom involved due to the complexity of physical interaction and the high computational cost. In this paper, we present a novel method to animate realistic interaction between grass and dynamic objects. The representation of large-scale grassland relies on three different levels of detail that could reduce the rendering cost and still allow high-fidelity rendering of grasses close to the viewer. According to different levels of detail, two animation approaches are applied: physically-based method, which deals with the deformation of geometricalbased grass blades that close to the viewer;procedural method, which handles billboard-based grass. Besides, seamless dynamic transition between different levels is taken into account. Experiments demonstrate our method not only can realistically simulate the interaction between massive amounts of grass and the dynamic object, but also can overcome the deficiencies of existing approaches.
A new linear prediction-based haptic data reduction technique is presented. The prediction approach relies on the least-squares method to reduce the number of data packets. Knowledge from human haptic perception is in...
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ISBN:
(纸本)9783037857243
A new linear prediction-based haptic data reduction technique is presented. The prediction approach relies on the least-squares method to reduce the number of data packets. Knowledge from human haptic perception is incorporated into the architecture to assess the perceptual quality of the compressed haptic signals. Experiments prove the effectiveness of the proposed approach in data reduction rate.
Cooperative communication can achieve spatial diversity gains,and consequently combats signal fading due to multipath propagation in wireless networks powerfully.A novel complex field network-coded cooperation（CFNCC...
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Cooperative communication can achieve spatial diversity gains,and consequently combats signal fading due to multipath propagation in wireless networks powerfully.A novel complex field network-coded cooperation（CFNCC） scheme based on multi-user detection for the multiple unicast transmission is *** analysis and simulation results demonstrate that,compared with the conventional cooperation（CC） scheme and network-coded cooperation（NCC） scheme,CFNCC would obtain higher network throughput and consumes less time ***,a further investigation is made for the symbol error probability（SEP） performance of CFNCC scheme,and SEPs of CFNCC scheme are compared with those of NCC scheme in various scenarios for different signal to noise ratio（SNR） values.
In multi-hop wireless ad-hoc networks, packet delivery delay is one of the most important performance metrics. While a lot of research efforts have been spent on measuring and optimizing the end-to-end delay performan...
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In multi-hop wireless ad-hoc networks, packet delivery delay is one of the most important performance metrics. While a lot of research efforts have been spent on measuring and optimizing the end-to-end delay performance, there usually lack accurate and lightweight methods for decomposing the end-to-end delay into the per-hop delay for each packet. Knowledge on the per-hop per-packet delay can greatly improve the network visibility and facilitate network measurement and management. In this paper, we propose Domo, a passive, lightweight and accurate delay tomography approach to decomposing the packet end-to-end delay into each hop. The basic idea is to formulate the problem into a set of optimization problems by carefully considering the constraints among various timing quantities. At the network side, Domo attaches a small overhead to each packet for constructing constraints of the optimization problems. At the PC side, Domo employs semi-definite relaxation and several other methods to efficiently solve the optimization problems. We implement Domo and evaluate its performance extensively using large-scale simulations. Results show that Domo significantly outperforms two existing methods, nearly tripling the accuracy of the state-of-the-art.
This paper proposes a locality correlation discriminant with neighborhood preserving embedding for face recognition, which considers both the locality correlation and manifold structure of the training data. A new loc...
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A new generation of active 3D range sensors, such as time-of-flight cameras, enables recording of full-frame depth maps at video rate. Unfortunately, the captured data are typically contaminated by noise and have only...
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k-Nearest Neighbour (KNN) is one of the most popular algorithms for pattern recognition and data classification, but the traditional KNN classification method has some disadvantages. In this paper, aim at the KNN clas...
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Recently, Wang et al. presented a new construction of attribute-based signature with policy-and-endorsement mechanism. The existential unforgeability of their scheme was claimed to be based on the strong Diffie-Hellma...
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Recently, Wang et al. presented a new construction of attribute-based signature with policy-and-endorsement mechanism. The existential unforgeability of their scheme was claimed to be based on the strong Diffie-Hellman assumption in the random oracle model. Unfortunately, by carefully revisiting the design and security proof of Wang et alfs scheme, we show that their scheme cannot provide unforgeability, namely, a forger, whose attributes do not satisfy a given signing predicate, can also generate valid signatures. We also point out the flaws in Wang et al.＇s proof.
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