Displacement Mapping using Scan Conversion Hardware Architectures

This paper presents a novel algorithm and architectures for perspective correct displacement of the surface geometry of a polygonal model using a displacement map. This new displaced surface geometry is passed onto a traditional rendering pipeline. The algorithm uses a multiple pass approach in which the geometry is displaced in the first pass and then the displaced geometry is rendered. The significant features of the algorithm are that the surface is displaced after its triangle mesh is transformed into screen space and that it uses only bi-linear interpolation for calculating the displaced geometry allowing a cheap incremental scan-line implementation. A hardware architecture based on this algorithm is presented along with possible alternative implementations. The technique presented here allows greater photorealism by using increased detail without an increase in bandwidth for geometry or calculation time for transformation.     

基于图形硬件的纹理图像编码与实时绘制算法

真实感绘制对于细节的要求越来越高,应用程序通常采用多幅或大幅分辨率很高的纹理图像,有限的内存空间就成了一个制约的瓶颈.针对纹理图像的特点和可编程图形硬件的特殊要求,该文提出了一种新的面向绘制的编码算法--增量式纹理编码算法及相应的解压绘制算法,有效地解决了纹理存储容量和真实感之间的矛盾,并利用可编程图形硬件实现了实时解压绘制.该算法在图像压缩编码过程中,动态添加码表内容,只有当已有码表内容不能表示当前图像区域时,才增加码表内容.这种方法不仅能够对于自相似性较强的纹理图像取得很高的压缩比,而且由于码表的动态更新特性,可以对图像序列进行流式编码.在绘制纹理时,该算法充分利用了现有可编程图像硬件的特性,实现了实时解压绘制.文中分别对于静态图像和动态图像序列进行了实验,结果显示,此方法能灵活有效地对各类纹理图像进行编码.     

支持高级明暗处理和凸凹纹理映射的硬件体系结构

Ｐｈｏｎｇｓｈａｄｉｎｇ和Ｂｕｍｐｍａｐｐｉｎｇ技术被认为是下一代图形硬件必须支持的基本技术,因而是目前图形硬件研究突破的重点．但到目前为止,尚未找到一种被广泛认可的有效的硬件实现算法．本文对这一研究领域的一些实现方案做了初步的分析比较,试图找到一种有效的新的体系结构,它既能继承图形硬件已有的成果,又能对新的技术提供有效的支持．     

图形处理中投影变换的硬件设计与验证

描述了基于浮点处理单元的投影变换的硬件实现。以提高速度为设计目标,采用Verilog语言进行设计和实现,使用ISE进行逻辑综合,并用SystemVerilog进行建模验证。结果表明,本设计极大地提高了图形处理的速度。     

A Texture Mapping Approach to 3-D Facial Image Synthesis

A method of synthesising and animating a realistic image of a person's face by means of computer graphics is described. The key feature contributing to realism in image synthesis lies in the use of texture mapping in the rendering of surface detail on the face. Full facial animation is made possible by manipulating a 3-D model of the face in conjunction with a relatively small data set of pre-stored sub-images.     

一个适合图形算法硬化的通用硬件设计

提高图形处理速度是计算机图形学硬件的发展方向。图形处理过程的硬化研究是至关重要的一环。本文介绍一个采用高速位片系列芯片和微程序控制技术的硬件系统，这一系统是一个方便的图形算法硬化的硬件仿真器。     

Visualizing Objects with Mirrors

We present an automatic camera and mirrors placement method for visualizing 3D scenes such that complete and nonredundant visibility is guaranteed, as well as highest image resolution. We provide algorithms and geometries for optimal object‐independent mirrors and viewpoint placement for all objects in a specific class. We also briefly consider object‐dependent algorithmic problems, where mirrors and viewpoints are positioned as a function of the object.     

工程工作站技术进展

本文简要地分析了工程工作站的特征,提出工程工作站是集运算、图形处理以及网络功能于一体的计算机系统。本文给出了工程工作站组成与性能指标分析,重点介绍工程工作站技术在运算部件、图形处理部件以及体系结构等方面的进展,最后总结了工程工作站成功的技术因素。     

基于图像的光照模型的研究与实现

为了把计算机生成的虚拟物体更好地融入真实场景的实拍照片中，实现光照一致性的效果，提出了一个基于图像的光照模型，它使用光测图作为光源从而实现对场景的照明。在研究基于图像的局部光照模型时，又提出了双向折射率分布函数这一概念，从而简化了局部光照模型的设计。在实现阶段，采用立方体环境映照来表示场景，采用光测图记录环境映照中光辐射的分布信息，从而提高了绘制效率。实验表明，本模型较成功地实现了光照一致性，在增强现实、图像合成等方面具有很大的应用价值。     

一种基于交互式多维传递函数的纹理映射体绘制算法

本文设计了一种基于空间信息的交互式多维传递函数的纹理映射体绘制算法。该算法不仅可以根据体数据的强度而且还利用体素的空间位置来设定绘制的颜色和阻光度。通过采用一种独特的空间投影变换,根据用户需求,将体数据划分为不同区域,并分别定义各自的传递函数。该特点使得本文的算法可以有效地对体数据进行交互式分析。在算法实现中,利用了通用图形硬件的可编程特性,在普通PC上可以达到理想的绘制质量和交互速度。     

Method of direct texture synthesis on arbitrary surfaces

A direct texture synthesis method on arbitrary surfaces is proposed in this paper. The idea is to recursively map triangles on surface to texture space until the surface is completely mapped. First, the surface is simplified and a tangential vector field is created over the simplified mesh. Then, mapping process searches for the most optimal texture coordinates in texture sample for each triangle, and the textures of neighboring triangles are blended on the mesh. All synthesized texture triangles are compressed to an atlas. Finally, the simplified mesh is subdivided to approach the initial surface. The algorithm has several advantages over former methods: it synthesizes texture on surface without local parameterization; it does not need partitioning surface to patches; and it does not need a particular texture sample. The results demonstrate that the new algorithm is applicable to a wide variety of texture samples and any triangulated surfaces.     

Visualizing and animating the winged-edge data structure

The winged- and half-edge data structures are commonly used representations for polyhedron models. Due to the complexity, students in an introductory course to computer graphics usually have difficulty in handling these data structures and developing applications. This paper describes the authors’ effort in the development of a visualization and animation tool for teaching and learning these data structures. This tool also includes a simple pseudo-code-like language for algorithm design. Instructors may employ this tool for presentation and demonstration purposes. Students may use the simple language to develop and experiment with new algorithms before their actual implementation. The visualization and animation system may be used to explore and understand the relationship among mesh elements and algorithm execution.     

IBCD: a fast collision detection algorithm based on image space using OBB

Image‐based collision detection algorithms make efficient use of the graphics rendering hardware and reduce the computational cost of CPU. In this article, a fast collision detection algorithm based on image space is presented, which combines graphics hardware capabilities with a simplified geometric representation (oriented bounding box) in order to rapidly detect collisions between complex objects. The method can deal with arbitrary polyhedra, while preserving the merits of image‐based collision detection algorithms. This is achieved by decomposing the surfaces of an object into a list of convex pieces. High efficiency of the algorithm is obtained by organizing the convex pieces into a binary tree with each node representing a convex piece, and by adopting triangle strip compression. The algorithm has been implemented and compared with related algorithms. Copyright © 2003 John Wiley & Sons, Ltd.     

在可编程图形硬件上实现图像高动态范围压缩

通过在亮度图像梯度域上对大梯度进行衰减,压缩图像亮度的动态范围,可以使高动态范围图像在被显示时,既能够适应常规的显示硬件,同时又充分保留原始图像的细节信息,使得图像在被观察时能够重现真实场景的亮度效果。文中采用适合由图形处理器加速的快速算法,将整个处理过程通过可编程图形硬件实现,建立快速的图像动态范围压缩技术,建立起适用于高动态范围图像显示的实时应用框架,使之不仅适用于基于图像的动态范围调整的绝大部分情况,还能够成为各种交互式图形应用的核心技术之一。     

一种图形光栅的硬件实现算法

提出了一种面向嵌入式平台的图形光栅的硬件实现算法。将三角面包围盒内的像素分成多个规则像素块,在像素块基础上进行扫描转换和像素插值以及透视校正。在对算法做了大量优化后,用FPGA(现场可编程门阵列)对算法进行了实现和验证。与传统的光栅算法相比,提出的算法提高了像素命中率,减小了计算复杂度,降低了硬件成本。验证结果表明,算法渲染的图形质量达到OpenGLES 1.1渲染效果;在一般场景下的渲染速度达到30帧/秒,满足实时渲染要求;在Xilinx FPGA Vertex2P xc2vp30-7ff89上的综合资源为5 545个Slice,硬件消耗较小。     

Fast and simple hardware accelerated voxelizations using simplicial coverings

Voxelization of solids, that is the representation of a solid by a set of voxels that approximates it, is an operation with important applications in fields like solid modeling, physical simulation or volume graphics. Moreover, the new generation of affordable 3D raster displays has renewed the interest on fast voxelization algorithms, as the scan-conversion of a solid is a basic operation on these devices. In this paper a hardware accelerated method for computing a voxelization of a polyhedron is presented. The algorithm is simple, efficient, robust and handles any kind of polyhedron (self-intersecting, with or without holes, manifold or non-manifold). Three different implementations are described in detail. The first is a conventional implementation in the CPU, the second is a hardware accelerated implementation that uses standard OpenGL primitives, and the third exploits the capabilities of modern GPUs by using vertex programs.     

屏幕空间自适应的地形Tessellation绘制

为了在大规模真实感地形渲染中利用GPU硬件加速的Tessellation技术,在对地形Tessellation原理分析的基础上,提出一种屏幕空间自适应的地形Tessellation绘制算法,实现了在GPU内部对地形模型的三角形自适应细分。该算法采用Tile和Patch的形式对地形数据进行分层组织,在CPU和GPU上分别以Tile和Patch为基础实现地形LOD(level of detail)的自适应简化;提出在Hull Shader上基于Patch边界的细分系数计算模型,确保了Patch细分时的无缝连接;给出了Domain Shader上置换贴图的处理过程,以实现细分顶点的高程纹理映射;并且采用了两级视锥体裁剪机制,减少了渲染数据的冗余量。实验结果表明,该算法具有较好的屏幕空间自适应性和渲染性能,能够在输入粗糙网格的基础上,渲染输出高分辨率几何细节特征的地形模型。     

一种基于GPU硬件加速计算的辐射度实现方法

提出一种新的基于GPU(graphics processing unit)的辐射度方法．该方法利用可编程图形处理单元GPU的并行计算能力,将辐射度方法中形状因子计算以及线性方程组求解的全过程完全在可编程图形硬件中完成,避免了原有基于GPU的辐射度方法需要CPU参与的问题,绕开了计算机主内存与GPU纹理内存之间数据交换的瓶颈;在基于半立方体法的形状因子计算和绘制过程中,解决了基于GPU硬件加速的遍历、分类和累加问题．此外,该方法采用新的矩阵和向量在GPU中的存储方法,利用GPU实现Jacobi迭代法快速求解线性方程组．实验结果证明。该方法能够快速有效地实现辐射度的计算和绘制．     

A Unified, Object-Oriented Graphics System and Software Architecture for Visualising CAD/CAM Presentations

Most object-oriented graphics systems (OOGS) either support general purpose graphics capabilities (drawing editors, ray tracing, etc.), or have targeted specific areas of computer graphics, for example, interface building, animation, and visualisation. However, the key concept in CAD/CAM graphics systems is that of presentations—pictures that convey information about products or parts of products. CAD/CAM graphics systems that create and manipulate presentations have specific graphical requirements that have not been addressed by existing OOGS. These requirements include the support of CAD/CAM concepts such as drawings, views and view-specific graphics, and layers, and the ability to allow external geometric modelers to be linked into the presentation. We describe an object-oriented presentation architecture that allows the application to describe the structure of the CAD/CAM presentation. This architecture provides a unified interface to drawings, views, layers and entities, and allows linkage to models created with an external geometric modeler, while isolating applications from details of the underlying traditional graphics rendering systems. It is our hope that this architecture provide the foundation for the architecture of next generation OOGS. We also present an implementation of this architecture and compare it to other OOGS.     

一种图形加速器和着色器的体系结构

为了适应智能手机和网本机对于图形加速器的需求,提出一种二维图形加速器和三维像素着色器的体系结构.该体系结构包括自主设计的VLIW指令集和可重组的数据驱动流水线.针对通常将图像帧划分成多个块,且每块由一个微引擎处理的方法可能造成微引擎的负载不均衡的问题,采用按扫描行分配的并行存储和处理结构,其中每个扫描行的处理任务按照需要动态地分配给微引擎.为了评估和实现该体系结构,建立了性能仿真平台、系统仿真平台和RTL仿真平台,并用C++语言编写性能仿真平台评估了该体系结构对性能的影响.模拟实验结果表明,新颖的存储/任务映射方法可以充分地利用处理器资源,降低存储访问的冲突,有利于改善并行处理的可扩展性.文中还讨论了自主设计的图形产生器、图像变换器和VLIW微引擎的结构以及相关的图形硬件加速算法.