共查询到20条相似文献,搜索用时 20 毫秒
1.
The objective of this paper is to adapt photon mapping for real-time simulation of caustics. High-performance algorithm adapted
for the GPU and implemented on the basis of cross-platform OpenGL and OpenCL APIs is proposed. For effective rendering of
caustics and generation of photon map OpenGL shaders are used. Voxel acceleration structure constructed directly on the GPU
by means of OpenCL provides fast access to photon map. Performance estimation for different equipment is given. 相似文献
2.
3.
《Computers & Geosciences》2006,32(1):73-84
Volume rendering methods enable the user to explore interactively scalar data on regularly spaced three-dimensional grids. This article discusses how to use this method to explore and analyse three-dimensional tensor fields. The proposed visualization makes use of the programmability of modern graphics hardware and of “Line Integral Convolution”, a texture-based technique for the visualization of vector fields. While an example from geomechanics is used for presentation purposes, the rendering methods introduced are generic and would suit other application areas that involve volumetric data with several attributes equally well. 相似文献
4.
Interactive view-dependent rendering over networks 总被引:1,自引:0,他引:1
Zheng Z Prakash E Chan TK 《IEEE transactions on visualization and computer graphics》2008,14(3):576-589
For a client-server based view-dependent rendering system, the overhead of view-dependent rendering and the network latency are major obstacles in achieving interactivity. In this paper, we first present a multiresolution hierarchy traversal management strategy to control the overhead of view-dependent rendering for low-capacity clients. Then we propose a predictive parallel strategy to overcome the network latency for client-server based view-dependent multiresolution rendering systems. Our solution is to make the client process and the server process run in parallel, using the rendering time to cover the network latency. For networks with long round-trip times, we manage to overlap the network latency for one frame with the rendering time for multiple frames. View-parameters prediction is incorporated to make the parallelism of the client and the server feasible. In order to maintain an acceptable view-dependent rendering quality in the network environment, we develop a synchronization mechanism and a dynamic adjustment mechanism to handle the transient network slowdowns and the changes of the network condition. Our experimental results, in comparison with the sequential method, show that our predictive parallel approach can achieve an interactive frame rate while keeping an acceptable rendering quality for large triangle models over networks with relatively long round-trip times. 相似文献
5.
In this paper we present a novel real-time cartoon-style rendering approach, which targets very large meshes. Cartoon drawing
usually uses a limited number of colors for shading and emphasizes special effects, such as sharp curvature and silhouettes.
It also paints the remaining large regions with uniform solid colors. Our approach quantizes light intensity to generate different
shadow colors and utilizes multiresolution mesh hierarchy to maintain appropriate levels of detail across various regions
of the mesh. To comply with visual requirements, our algorithm exploits graphics hardware programmability to draw smooth silhouette
and color boundaries within the vertex and fragment processors. We have adopted a simplification scheme that executes simplification
operators without incurring extra simplification operations as a precondition. The real-time refinement of the mesh, which
is performed by the graphics processing unit (GPU), dramatically improves image quality and reduces CPU load. 相似文献
6.
Fluid simulations typically produce complex three-dimensional (3D) isosurfaces whose geometry and topology change over time. The standard way of representing such "dynamic geometry" is by a set of isosurfaces that are extracted individually at certain time steps. An alternative strategy is to represent the whole sequence as a four-dimensional (4D) tetrahedral mesh. The iso-surface at a specific time step can then be computed by intersecting the tetrahedral mesh with a 3D hyperplane. This not only allows the animation of the surface continuously over time without having to worry about the topological changes, but also enables simplification algorithms to exploit temporal coherence. We show how to interactively render such 4D tetrahedral meshes by improving previous GPU-accelerated techniques and building an out-of-core multi-resolution structure based on quadric error simplification. As a second application, we apply our framework to time-varying surfaces that result from morphing one triangle mesh into another. 相似文献
7.
NURBS (Non-uniform rational B-splines) surfaces are one of the most useful primitives employed for high quality modeling in CAD/CAM tools and graphics software. Since direct evaluation of NURBS surfaces on the GPU is a highly complex task, the usual approach for rendering NURBS is to perform the conversion into Bézier surfaces on the CPU, and then evaluate and tessellate them on the GPU. In this paper we present a new proposal for rendering NURBS surfaces directly on the GPU in order to achieve interactive and real-time rendering. Our proposal, Rendering Pipeline for NURBS Surfaces (RPNS), is based on a new primitive KSQuad that uses a regular and flexible processing of NURBS surfaces, while maintaining their main geometric properties to achieve real-time rendering. RPNS performs an efficient adaptive discretization to fine tune the density of primitives needed to avoid cracks and holes in the final image, applying an efficient non-recursive evaluation of the basis function on the GPU. An implementation of RPNS using current GPUs is presented, achieving real-time rendering rates of complex parametric models. Our experimental tests show a performance several orders of magnitude higher than traditional approximations based on NURBS to Bézier conversion. 相似文献
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9.
Lauterbach C Chandak A Manocha D 《IEEE transactions on visualization and computer graphics》2007,13(6):1672-1679
We present a new approach for simulating real-time sound propagation in complex, virtual scenes with dynamic sources and objects. Our approach combines the efficiency of interactive ray tracing with the accuracy of tracing a volumetric representation. We use a four-sided convex frustum and perform clipping and intersection tests using ray packet tracing. A simple and efficient formulation is used to compute secondary frusta and perform hierarchical traversal. We demonstrate the performance of our algorithm in an interactive system for complex environments and architectural models with tens or hundreds of thousands of triangles. Our algorithm can perform real-time simulation and rendering on a high-end PC. 相似文献
10.
Przemyslaw Krompiec Kyoungju Park Dongxue Liang Changmin Lee 《The Visual computer》2016,32(6-8):813-823
We present an automatic and robust technique for creating non-photorealistic rendering (NPR) and animation, starting from a video that depicts the shape details and follows the motion of underlying objects. We generate NPR from the initial frame of the source video using a greedy algorithm for stroke placements and models, in combination with a saliency map and a flow-guided difference-of-Gaussian filter. Our stroke model uses a set of triangles whose vertices are particles and whose edges are springs. Using a physics-based framework, the generated and rendered strokes are translated, rotated and deformed by forces exerted from the sequential frames. External forces acting on strokes are calculated according to temporally and spatially smoothed per-pixel optical flow vectors. After simulating each frame, we delete unnecessary strokes and add new strokes for disappearing and appearing objects, but only if necessary to avoid popping and scintillation. Our framework automatically generates the coherent animation of rendered strokes, preserving the appearance details and animating strokes along with the underlying objects. This had been difficult to achieve with previous user-guided methods and automatic but limited transformations methods. 相似文献
11.
针对物体表面镜面反射现象的绘制,提出了一种新的基于二维纹理映射技术的加速算法。将具有镜面反射表达式的Phong模型分解成多个简单的数学函数,预先离散采样计算后作为纹理对象传给显卡。使用OpenGL多重纹理技术,将每个纹理对象放入相应的纹理单元,分别设置其组合函数,将多个纹理的运算组合起来。将三角片顶点坐标及多组纹理坐标传入,从而实现了物体镜面反射现象的实时绘制。实验结果表明,该算法大大提高了绘制的性能。 相似文献
12.
Georgios Sakas 《The Visual computer》1993,9(8):425-438
We first present the volume-rendering pipeline and the most typical of the existing methods for each pipeline stage. The complexity of each stage in terms of computing time is analyzed for each method. Then the demands and the scope of interactive volume rendering are briefly summarized. Based on this analysis we examine alternate solutions to optimize each pipeline stage in order to allow interactive visualization while maintaining the image quality. The proposed method maximizes interactive manipulation possibilities and minimizes runtimes by sampling at the Nyquist rate and by flexibly trading off quality for performance at any pipeline level. Our approach is suitable for rendering large, scalar, discrete volume fields such as semitransparent clouds (or X-rays) on the fly. 相似文献
13.
This paper proposes a novel architecture called Grouped Photon Mapping, which combines standard photon mapping with the light-beam
concept to improve the nearest-neighbor density estimation method. Based on spatial coherence, we cluster all of photons,
which are deposited in the photon map, into different beam-like groups. Each group of photons is individually stored in an
isolated photon map. By the distribution of the photons in each photon map, we construct a polygonal boundary to represent
a beam-like illuminated area. These boundaries offer a more accurate and flexible sampling area to filter neighbor photons
around the query point. In addition, by a level of detail technique, we can control the photon-count in each group to obtain
a balance between biases and noise. The results of our experiments prove that our method can successfully reduce bias errors
and light leakage. Especially, for complicated caustic effects through a gemstone-like object, we can render a smoother result
than standard photon mapping. 相似文献
14.
Interactive stereoscopic rendering of volumetric environments 总被引:1,自引:0,他引:1
Wan M Zhang N Qu H Kaufman AE 《IEEE transactions on visualization and computer graphics》2004,10(1):15-28
We present an efficient stereoscopic rendering algorithm supporting interactive navigation through large-scale 3D voxel-based environments. In this algorithm, most of the pixel values of the right image are derived from the left image by a fast 3D warping based on a specific stereoscopic projection geometry. An accelerated volumetric ray casting then fills the remaining gaps in the warped right image. Our algorithm has been parallelized on a multiprocessor by employing effective task partitioning schemes and achieved a high cache coherency and load balancing. We also extend our stereoscopic rendering to include view-dependent shading and transparency effects. We have applied our algorithm in two virtual navigation systems, flythrough over terrain and virtual colonoscopy, and reached interactive stereoscopic rendering rates of more than 10 frames per second on a 16-processor SGI challenge. 相似文献
15.
The authors introduce a new approach for the deformation of surface and raster models in two and three dimensions. Rather than deforming the model, they deform the agents employed to render it. The method uses one deformation tool (the deflector) to deform any object that is ray traceable. Based on deforming the rendering primitives rather than objects, the approach invests computation effort only in those regions of the model that contribute to the final image 相似文献
16.
通过对渐进式光子映射算法进行扩展,提出了一种基于自适应光子发射的渐进式光子映射算法.渐进式光子映射是一个多遍的全局光照算法,通过不断发射光子并渐进更新场景各点的光能估计能使其最终能收敛到无偏差的结果.由于渐进式光子映射完全使用密度估计来计算各点的光能,因此其收敛速度受光子分布影响较大.利用渐进式光子映射算法中固有的场景统计信息以及其多遍的特点,设计了一个自适应的光子发射策略,使得发射的光子能更多的分布在对最终绘制有效的区域,提高了原算法的绘制效率. 相似文献
17.
Interactive volume rendering of large sparse data sets using adaptive mesh refinement hierarchies 总被引:2,自引:0,他引:2
Kahler R. Simon M. Hege H.-C. 《IEEE transactions on visualization and computer graphics》2003,9(3):341-351
In this paper, we present an algorithm that accelerates 3D texture-based volume rendering of large, sparse data sets, i.e., data sets where only a traction of the voxels contain relevant information. In texture-based approaches, the rendering performance is affected by the fill-rate, the size of texture memory, and the texture I/O bandwidth. For sparse data, these limitations can be circumvented by restricting most of the rendering work to the relevant parts of the volume. In order to efficiently enclose the corresponding regions with axis-aligned boxes, we employ a hierarchical data structure, known as an AMR (adaptive mesh refinement) tree. The hierarchy is generated utilizing a clustering algorithm. A good balance is thereby achieved between the size of the enclosed volume, i.e., the amount to render in graphics hardware and the number of axis-aligned regions, i.e., the number of texture coordinates to compute in software. The waste of texture memory by the power-of-two restriction is minimized by a 3D packing algorithm which arranges texture bricks economically in memory. Compared to an octree approach, the rendering performance is significantly increased and less parameter tuning is necessary. 相似文献
18.
Computational simulations frequently generate solutions defined over very large tetrahedral volume meshes containing many millions of elements. Furthermore, such solutions may often be expressed using non-linear basis functions. Certain solution techniques, such as discontinuous Galerkin methods, may even produce non-conforming meshes. Such data is difficult to visualize interactively, as it is far too large to fit in memory and many common data reduction techniques, such as mesh simplification, cannot be applied to non-conforming meshes. We introduce a point-based visualization system for interactive rendering of large, potentially non-conforming, tetrahedral meshes. We propose methods for adaptively sampling points from non-linear solution data and for decimating points at run time to fit GPU memory limits. Because these are streaming processes, memory consumption is independent of the input size. We also present an order-independent point rendering method that can efficiently render volumes on the order of 20 million tetrahedra at interactive rates. 相似文献
19.
An artist’s painting is affected by factors such as how he observes objects, his skill in using a brush and materials, and the experience that allows him to correctly apply his skills. The process inevitably results in mistakes contrary to the painter’s original intention. This is a distinguishing factor between painting and photography, but this is the essence of the beauty of painting. The inadequacy of a human being to make a painting exactly as he pleases (as a photograph creates a direct representation of itself) is the starting point of creating a creative work. This paper explains the algorithm that reproduces human errors, as well as the stroke data collection method. Although the results of this research are mainly stylized renderings of modern oil paintings, they have unlimited scalability, in that they can play the role to perform a basic framework. These allow the experimentation with many painting styles through the modification of input data and error generation algorithms. 相似文献
20.
We present an efficient point-based isosurface exploration system with high quality rendering. Our system incorporates two point-based isosurface extraction and visualization methods: edge splatting and the edge kernel method. In a volume, two neighboring voxels define an edge. The intersection points between the active edges and the isosurface are used for exact isosurface representation. The point generation is incorporated in the GPU-based hardware-accelerated rendering, thus avoiding any overhead when changing the isovalue in the exploration. We call this method edge splatting. In order to generate high quality isosurface rendering regardless of the volume resolution and the view, we introduce an edge kernel method. The edge kernel upsamples the isosurface by subdividing every active cell of the volume data. Enough sample points are generated to preserve the exact shape of the isosurface defined by the trilinear interpolation of the volume data. By employing these two methods, we can achieve interactive isosurface exploration with high quality rendering. 相似文献