41671130
Accelerated backward warping
In this paper a plane-based backward warping algorithm is proposed to generate novel views from multiple reference images. first, depth information is employed to reconstruct space planes from individual reference images and calculate the potential occluding relationship between these planes. Then the planes which represent each identical space plane from different reference images are compared with each other to decide the one with the best sample rate to be preserved and used in the later warping period while the other samples are abandoned. While the image of a novel view is produced, traditional methods in computer graphics, such as visibility test and clipping, are used to process the planes reconstructed. Then the planes processed are projected onto the desired image from the knowledge on which plane the desired image pixels are warped from can be acquired. Finally, pixels' depth of the desired image is calculated and then a backward warping is performed from these pixels to the reference images to obtain their colors. The storage requirement in the algorithm is small and increases slowly with the number of reference images increases. By combining the strategy of only preserving the best sample parts and the backward warping algorithm, the sample problem could be well tackled.
16235665
Real-time 3D fluid simulation on GPU with complex obstacles
In this paper, we solve the 3D fluid dynamics problem in a complex environment by taking advantage of the parallelism and programmability of GPU. In difference from other methods, innovation is made in two aspects. Firstly, more general boundary conditions could be processed on GPU in our method. By the method, we generate the boundary from a 3D scene with solid clipping, making the computation run on GPU despite of the complexity of the whole geometry scene. Then by grouping the voxels into different types according to their positions relative to the obstacles and locating the voxel that determines the value of the current voxel, we modify the values on the boundaries according to the boundary conditions. Secondly, more compact structure in data packing with flat 3D textures is designed at the fragment processing level to enhance parallelism and reduce execution passes. The scalar variables including density and temperature are packed into four channels of texels to accelerate the computation of 3D Navier-Stokes equations (NSEs). The test results prove the efficiency of our method, and as a result, it is feasible to run middle-scale problems of 3D fluid dynamics in an interactive speed for more general environment with complex geometry on PC platform.
17132126
Recovery of material under complex illumination conditions
To calculate the inter-reflection between real objects and virtual ones in augmented reality, recovery of material for the real objects is necessary. In this paper, an approach is proposed to recover the material properties from a single high dynamic range image for a homogeneous object under complex illumination conditions. By the method, we first acquire a high dynamic range image for the object, and one or a few environment maps in high dynamic range as illumination of the object. Then a simulated annealing algorithm is employed to solve the inverse rendering problem. Finally, we obtain optimal parameter values for the reflection model in approximating the material of the object. In the course of optimization, image-based lighting and ray tracing techniques are used, and as a result the inter-reflection can be calculated in convenience. In addition, the transparent and translucent properties can be also recovered.
34486970
Simulation of miscible binary mixtures based on lattice Boltzmann method
Miscible fluid mixtures, like pouring honey into water, Coca Cola into strong wine, are common phenomena in our daily life. While two miscible fluids are mixed together, their appearances in terms of colors and shapes will change due to their mixing interaction. The interaction between the mixture components could be regarded as a combination of the diffusing process and demixing process. If the former dominates the interaction, it is miscible; otherwise, it is immiscible. The complex microscopic interplay between the mixture components makes the simulation highly challenging. So far, there have been some dedicated research in computer graphics dealing with immiscible mixtures, but few works have been done focusing on miscible mixtures. In this paper, for the first time, we introduce a two-fluid lattice Boltzmann method (LBM), called TFLBM, applied to miscible binary mixtures. Different from other similar methods, the viscous and diffusing properties of the fluid in our work are considered separately, so that the physical insight is exposed more clearly and rationally. In addition, the operation of LBM is mostly a linear local computation, and graphics processing unit (GPU) has been utilized to achieve real-time simulation. Copyright © 2006 John Wiley & Sons, Ltd.
17696206
P-quadtrees: a point and polygon hybrid multi-resolution rendering approach
Point and polygon representations have their respective merits in rendering objects. In this paper, we propose a novel hybrid multi-resolution approach, PQuadtrees, to efficiently render highly detailed objects. PQuadtrees are constructed from geometry images. Both point and polygon are tightly integrated into a uniform structure. While traversing the P-Quadtrees in rendering, the part of surface that face the viewer can be rendered by coarser quad mesh to reduce the numbers of rendering primitives. The shading details can be enhanced by hardware accelerated normal mapping. The view dependent LOD selects the finer hierarchy on silhouette, which is rendered by points. The rendering of large-scale model is greatly accelerated while the visual effect both at the surfaces and the silhouette is guaranteed.
39271056
A hybrid representation of environment models in image-based real time walkthrough
In this paper, a hybrid representation of environment models using a combination of points and polygons is proposed. Through the model, a real time walkthrough of a complex environment can be achieved. We start from multiple depth reference images and classify the pixels of images into two categories, corresponding respectively to planar and non-planar surfaces in 3D space, then all the redundant points are removed by a comparison algorithm of sampling rate. For pixels corresponding to nonplanar surfaces, the point representation is maintained, and a local reconstruction and resampling process is employed to re-sample a set of points that distribute more uniformly on the surfaces. The re-sampled points are organized by an OBB-tree according to their space coordinates and a multiresolution structure is built to improve the rendering efficiency. For pixels corresponding to planar surfaces, the plane coefficients are reconstructed and all their appearances in the reference images are merged to texture maps. Under this hybrid representation, texture mapping and point-based rendering are employed to render the novel views, to take full advantage of the acceleration utility of graphics hardware. The algorithm demonstrates the combined advantages of approaches in traditional computer graphics and PBR/IBR, texture mapping for plane surfaces and point-based rendering for high detail surfaces and shapes.
8133100
Geometry-assisted statistical modeling for face mosaicing
The modeling of facial appearance has many applications. This paper proposes an approach to generating a statistical face model based on video mosaicing. Unlike traditional video mosaicing, we use the geometry of a face to improve the mosaicing result. Given a face sequence, each frame is unwrapped onto certain portion of the surface of a sphere, as determined by spherical projection and the minimization procedure using the Levenberg-Marquardt algorithm. A statistical model containing a mean image and a number of eigenimages, instead of only one image template, is used to represent the face mosaic. Good experimental results have been observed.
15191753
Power analysis of rotary clock
Rotary clock is a multi-gigahertz clock distribution technique based on the principle of wave propagation in transmission lines. In this paper, we perform the first quantitative investigation on the power dissipation of rotary clock designs. Specifically, we have developed a software tool based on the method of partial element equivalent circuit (PEEC) that is capable of extracting the SPICE netlist from a layout specification of a rotary clock design. As a result, we are able to accurately estimate the frequency and power dissipation of the rotary clock design using SPICE simulations. Using our tool, we have uncovered the key power dissipation mechanisms of rotary clock and proposed several power reduction strategies. Furthermore, our power analysis has revealed that rotary clock designs can achieve power savings of up to 70% in comparison with conventional clock tree implementations.
62445228
Practical repeater insertion for low power: what repeater library do we need?
This paper investigates the problem of repeater insertion for low power under a given timing budget. A novel repeater insertion algorithm is proposed to compute the optimal repeater number and width in the discrete solution space, as defined by a given repeater library. Using the proposed algorithm, two practical and highly important questions are addressed. Given a certain tolerance to the degradation of repeater power dissipation: 1) how coarse could the repeater size granularity be? 2) What range should repeater widths be in? The experimental results provide valuable insights into repeater library design. Specifically, the investigation reveals that coarse repeater size granularities can be used to reduce the library size by more than 87% with merely a 4% power degradation. Moreover, for two-pin interconnects with various wire lengths and timing targets, the range of optimal repeater sizes for low power is limited, indicating that a low-cost small-size repeater library, if well designed, is adequate to provide high-quality repeater insertion solutions. The proposed scheme can be used in early design stages to generate a compact repeater library that is passed on to other repeater insertion algorithms.
426496
Freeze: engineering a fast repeater insertion solver for power minimization using the ellipsoid method
This paper presents a novel repeater insertion algorithm for the power minimization of realistic interconnect trees under given timing budgets. Our algorithm judiciously combines a local optimizer based on the dynamic programming technique and a global search engine using the ellipsoid method. As a result, our approach is capable of producing high-quality solutions at a very fast speed. Furthermore, our scheme is robust and does not need any manual tuning of the iteration-control parameters. We have developed a repeater insertion tool, called Freeze, using the proposed algorithm and applied it to various interconnect trees with different timing targets. Experimental results demonstrate the high effectiveness of our approach. In comparison with the state-of-the-art low-power repeater insertion schemes, Freeze requires 5.8 times fewer iterations on the average, achieving up to 27 times speedup with even better power savings. When compared with a dynamic programming based scheme, which guarantees the optimal solution, our tool delivers up to 50 times speedup with 0.9% power increase on the average.
1644440
Design of a high-throughput low-power IS95 Viterbi decoder
The design of high-throughput large-state Viterbi decoders relies on the use of multiple arithmetic units. The global communication channels among these parallel processors often consist of long interconnect wires, resulting in large area and high power consumption. In this paper, we propose a data-transfer oriented design methodology to implement a low-power 256-state rate-1/3 IS95 Viterbi decoder. Our architectural level scheme uses operation partitioning, packing, and scheduling to analyze and optimize interconnect effects in early design stages. In comparison with other published Viterbi decoders, our approach reduces the global data transfers by up to 75% and decreases the amount of global buses by up to 48%, while enabling the use of deeply pipelined datapaths with no data forwarding. In the RTL implementation of the individual processors, we apply precomputation in conjunction with saturation arithmetic to further reduce power dissipation with provably no coding performance degradation. Designed using a 0.25 μ standard cell library, our decoder achieves a throughput of 20 Mbps in simulation and dissipates only 450 mW.