硬件加速反走样体Splatting算法

提出一个完全基于图形硬件实现的反走样体Splatting算法的全新框架利用可编程图形硬件中的顶点渲染器和像素渲染器实现距离相关的低通滤波核,获得透视投影下的Splatting体绘制算法的反走样利用规则体数据的空间分布规律和可编程图形流水线,提出一种增量式的压缩比为700 的顶点数据压缩算法,将体素几何完全置于显存实验结果表明,文中算法在512×512的图像分辨率下,每秒可绘制300万个反走样体素     

任意波形的彩色反走样算法研究与实现

由于智能仪器的不断发展,使用反走样技术来提高显示效果已成为一种趋势,针对现有反走样算法处理的图形种类比较单一的局限,设计了一种基于彩色图形的任意波形反走样方法。根据任意波数据的特征,对wu直线反走样算法进行了改进,使用连线的方式实现了任意波形的反走样。采用RGB颜色空间,根据亮度大小分别对前景色和背景色的3个分量值做处理,达到了任意背景色显示的要求。实验结果表明,该方法灵活高效、通用性强,能有效消除图形锯齿,且没有色彩失真。     

反走样技术在计算机图形仿真中的运用

阐述了反走样技术的基本原理和实现方法,重点描述了计算机图形中的直线反走样算法。该文采用的算法是基于三像素线宽的,通过调整像素的亮度来消除直线绘制中的锯齿现象。并把该算法推广到圆和椭圆的反走样。最后,采用改进的直线扫描转换算法与反走样算法相结合,进一步提高了反走样直线的绘制速度。该算法利用了直线的多段特性,以及空间对称特性。仿真表明,相比于Bresenham的算法,该算法的速度大为提高。     

面向延迟着色的统一反走样算法

近年来,面向延迟着色的后期处理反走样算法成为实时绘制研究和应用的热点,针对该算法往往只能处理单一类型的走样的问题,提出一种统一的后期处理反走样算法.该算法既能通过子像素级别的几何对几何边界进行高质量的反走样重建,又能根据着色信息对颜色纹理的走样进行形态学的反走样处理;由于使用2种屏幕空间反走样算法分类处理屏幕像素会导致2类像素之间过渡不平滑,在屏幕空间滤波的基础上使用重投影的反走样方法,能克服动态场景中可能出现的闪烁问题.实验结果表明,文中算法在延时绘制的框架下能较好地处理几何边界走样、纹理边缘走样和时间域走样等多种类型的走样,高效地获得高质量反走样绘制结果.     

纹理映射技术中Mip-Map的研究

在图形处理中,一个重要的研究方向是图形的真实感问题。纹理映射是高质量图像生成的一种重要技术,使三维图形更富真实感。Mip-Map纹理映射技术中,常常用一个正方形来近似表示象素在纹理空间的投影,但是像素投影并非正方形,是各向异性的,所以这种方法不符合反走样的要求,本文提出改进d值算法和长方形区域采样两种改进的算法来实现反走样。     

基于梯形阴影映射技术的平截头体交汇算法

阴影映射是在三维计算机图形中加入阴影的过程,在三维动画中有广泛的应用,但该算法容易产生走样,使用一种基于梯形阴影映射的平截头体交汇算法,对阴影映射进行了反走样处理。实验表明,该方法对于阴影映射分辨率和它们之间平滑过渡的总体能够有很好的把握和控制,能够生成高质量的阴影。     

Nano—X图形引擎算法优化

Nano—X是一个基于客户端／服务器（C／S）#系结构的GUI,系统结构采用分层设计,包括设备驱动层、图形引擎层和应用接口层。Nano—X系统稳定且具有良好的可裁剪性和较高的实时性,但图形引擎中未采用任何反走样算法,图形存在较严重的图形阶梯现象。为解决这一问题,基于Wu反走样算法提出了一种新型快速反走样算法,通过降低运算量提高了算法快速性。仿真结果表明该算法提高了绘图效率,明显减少阶梯现象,同时算法具有较高的实时性。     

反走样字符图形叠加算法与FPGA快速实现

为了提高机载平视显示系统中反走样字符图形与背景视频叠加输出的显示效果,提出一种反走样字符图形与视频叠加算法并通过FPGA快速实现。叠加过程中增加反走样字符图形背景融合计算,使反走样字符图形与背景视频叠加后边缘光滑过渡,系统使用两片DDR3分别存储视频和图形数据,两者并行处理,提高系统整体性能,优化背景融合算法DDR3实现流程,降低DDR3中断复杂度。结果表明,该系统整体性能得到提高,叠加融合画面效果良好,灵活性强,适用于机载座舱显示系统。     

高次幂函数逼近的阴影图反走样算法

针对传统阴影图算法由于阴影贴图分辨率的约束而在阴影的边缘会出现走样现象的问题,提出一种基于高次幂函数逼近的预滤波阴影图反走样算法.该算法使用高次幂函数来逼近传统阴影图中的深度比较函数,并对高次幂函数进行泰勒展开,在展开的各项上分别进行预滤波;在绘制过程中,利用泰勒展开式计算得到的数值代替传统阴影图中的深度比较函数得到的二值结果,从而实现了对阴影边缘的反走样.实验结果表明,该算法在现有图形硬件中能够达到很好的效果.     

基于点到直线距离的直线扫描转换算法

直线扫描转换算法是计算机图形学和计算机辅助设计等领域最基本、最重要的算法之一,直线反走样算法也是光栅化图形算法中的重要内容。文中提出了一种基于点到直线距离的直线扫描转换算法,给出了算法的推导过程及代码表示,并介绍了算法在直线反走样中的具体应用。该算法基于增量技术,采用点到直线的距离作为判别式,在扫描转换过程中,可方便地根据点到直线的距离,采用加权区域采样的方法进行直线的反走样,提高了反走样的效率;具有只使用整型变量、不涉及乘除运算的特点,适合硬件实现。     

A psychophysical approach to assessing the quality of antialiasedimages

The assumption that antialiasing destroys useful visual information about object features is challenged in three experiments that examine the effects of antialiasing on the visual information for object location and motion. The results show that proper antialiasing eliminates the spurious visual information produced by sampling processes in image synthesis and allows the viewer's visual system to produce a precise representation of object location and a continuous representation of object motion. This suggests that in designing imagery systems, simply increasing the spatial and temporal addressability and resolution beyond limits set by the human visual system will have a negligible impact on image quality, but that effective use of antialiasing techniques could allow visual information about object features to be presented with great fidelity     

Splatting errors and antialiasing

The paper describes three new results for volume rendering algorithms utilizing splatting. First, an antialiasing extension to the basic splatting algorithm is introduced that mitigates the spatial aliasing for high resolution volumes. Aliasing can be severe for high resolution volumes or volumes where a high depth of field leads to converging samples along the perspective axis. Next, an analysis of the common approximation errors in the splatting process for perspective viewing is presented. In this context, we give different implementations, distinguished by efficiency and accuracy, for adding the splat contributions to the image plane. We then present new results in controlling the splatting errors and also show their behavior in the framework of our new antialiasing technique. Finally, current work in progress on extensions to splatting for temporal antialiasing is demonstrated. We present a simple but highly effective scheme for adding motion blur to fast moving volumes     

Effect of display resolution and antialiasing on the discrimination of simulated-aircraft orientation

In Experiment 1, antialiasing was found to improve performance on an orientation-discrimination task, whereas increasing display pixel-count did not. The latter finding was attributed to a decrease in image contrast associated with driving the CRT beyond its effective bandwidth. In Experiment 2, it was found that display resolution is the primary determinant of orientation-discrimination performance. This performance was not significantly improved by increasing antialiasing beyond a minimal level, suggesting that greater image detail can be substituted for antialias filtering. Finally, data obtained from an objective target-size calibration showed that nominal target size often does not accurately reflect the size (and hence distance) of simulated targets.     

An Efficient 2½ D rendering and Compositing System

We describe a method for doing image compositing using either 2D geometric shapes or raster images as input primitives. The resolution of the final image is virtually unlimited but, as no frame buffer is used, performance is much less dependant on resolution than with standard painting programs, allowing rendering very large images in reasonable time. Many standard features found in compositing programs have been implemented, like hierarchical data structures for input primitives, lighting control for each layer and filter operations (for antialiasing or defocus).     

Jim Blinn's Corner-a trip down the graphics pipeline: subpixelicparticles

Reasons for subdividing pixels into subpixelic particles are discussed. Working with subpixel resolution in the floating-point domain is suggested as the easiest approach. To illustrate the use of floating-point pixel space, the arithmetic of two rendering algorithms is reviewed. The algorithms are an antialiased line renderer and a simple polygon tiler. Another use for subpixel resolution, i.e., doing antialiasing by subsampling is also considered. Using integer arithmetic in addition to subsampling is briefly discussed     

一种延期着色的快速反走样算法

使用延期着色技术,无法应用硬件对图形进行反走样处理。针对该问题,提出一种延期着色的快速反走样算法。利用缓存的位置和法线信息准确高效地在缓存中进行边缘检测,对边缘部分采用加权抖动采样方法进行平滑处理。实验表明,该算法能够快速地获得效果较好的反走样结果。     

On the Parameters of Human Visual Performance: An Investigation of the Benefits of Antialiasing

A two-part experiment was conducted to investigate the effects of aliasing artifacts and screen resolution on a simple visual recognition task. The results indicate that in many cases far less realism may be necessary in synthetic computer-generated imagery than is often assumed. The first part of the experiment was a subjective rating of image quality. The second part measured the relationship between image quality and task effectiveness: Subjects were asked to discriminate between images of two types of objects similar to objects used in experiments involving mental rotation. At higher resolutions, the elimination of aliasing artifacts did not significantly improve subjects' performances. At intermediate and low resolutions, comparable to what might be used for iconic menus, the reduction in aliasing artifacts improved performance. The subjective ratings indicate that for both high and low resolution the elimination of aliasing artifacts does not improve quality, whereas images rendered at intermediate resolutions are significantly degraded by aliasing artifacts to the extent that antialiasing improves the subjective rating. These results are interpreted in the context of an ongoing research program aimed at identifying the parameters of real-time human performance for graphics workstations.     

Metalights: Improved Interleaved Shading

We present metalights, a novel Virtual Point Light (VPL) encapsulating structure which enhances classic interleaved shading by improving VPL sampling, based on few initial screen space samples to estimate VPL contribution to current view. Our method leads to important noise variance reduction in the final picture by only adding a small fraction of computation. The implementation is straight‐forward and well adapted to both CPU and GPU‐based engines. We also present different image‐space assignment schemes for the VPL subsets to break the regularity of the noise pattern or to adapt it to simple antialiasing.     

Solving aliasing from shading with selective shader supersampling

Existing GPU antialiasing techniques, such as MSAA or MLAA, focus on reducing aliasing artifacts along silhouette boundaries or edges in image space. However, they neglect aliasing from shading in case of high-frequency geometric detail. This may lead to a shading aliasing artifact that resembles Bailey's Bead Phenomenon—the degradation of continuous specular highlights to a string of pearls. These types of artifacts are particularly striking for high-quality surfaces. So far, the only way of removing aliasing from shading is by globally supersampling the entire image with a large number of samples. However, globally supersampling the image is slow and significantly increases bandwidth consumption. We propose three adaptive approaches that locally supersample triangles only where necessary on the GPU. Thereby, we efficiently remove artifacts from shading while aliasing along silhouettes is reduced by efficient hardware MSAA.