基于延时光照的Cook-Torrance光照模型计算技术

真实感图形的实时绘制是虚拟现实技术和计算机游戏软件的一个重要组成部分,笔者提出了采用延时光照技术的Cook-Torrance光照模型快速计算方法。首先介绍了Cook-Torrance局部光照模型的原理和特点,阐述了延时光照处理的基本思想,提出了基于延时光照的Cook-Torrance计算模型,并应用现代图形硬件加速技术实现了Cook-Torrance快速实时的延时光照计算。实验表明采用该技术在获取更高照片质量真实感图形的同时,其运算速度也能满足交互系统的需求。     

多重散射的天空光照效果建模与实时绘制

依据大气散射的物理原理,提出了一种考虑多重散射的天空光照效果建模与实时绘制方法.该方法首先以太阳和天空光作为光源建立了多重散射的天空光照效果模型,然后综合多种大气粒子密度,采用合理的分段采样策略,对天空颜色模型的积分进行简化,以减少积分近似计算所带来的误差;通过对简化后的模型进行分析提出了采用二维纹理与三维纹理对光学深度预计算的方法,避免了运行时计算光学深度积分的问题;最后该算法在GPU的片段处理器上执行,实现了天空光照效果模型的实时绘制,可以满足各种实时应用需求.     

四维空间内的有限元体绘制转换函数设计

经典的有限元体绘制转换函数是定义在三维位置空间内的,然而有限元分析中还存在四维空间的数据,为了对该类数据进行显示,现提出一种面向四维有限元数据的体绘制转换函数模型.该模型结合有限元数据极大值区高关注度的特点和体绘制技术良好的数据筛选能力,在原有位置空间转换函数的基础上扩充第四维,以变换出时序体绘制效果和多标量体绘制效果.该模型的使用可极大的丰富有限元数据的图形显示方法.     

基于三维离散-连续耦合方法的NPR锚索-围岩相互作用机理研究

恒阻大变形(NPR)锚索作为一种高效的吸能锚索已广泛应用于边坡和采矿工程的加固和监测预警中。NPR锚索工作时的径向膨胀特性将影响整个锚固系统的性能。因此,基于离散元法(DEM)-有限差分法(FDM)耦合方法对静力拉伸作用下NPR锚索-围岩的相互作用机理进行分析。NPR锚索考虑为连续单元体,围岩和锚固材料由离散球体单元表征,将整个NPR锚固系统实现了离散元法与有限元法耦合模拟。围岩的离散元细观参数得到校准,NPR锚索的有限差分宏观参数由相应的静力拉伸室内试验进行验证。通过分析数值结果,对NPR锚索与NPR锚固系统的恒阻力进行了比较;描述了锚索-围岩界面的正应力与切应力的分布特征;此外,对锚固剂与围岩的破坏模式进行了细观研究。研究结果描述了NPR锚索与围岩的相互作用并揭示了NPR锚索的特殊锚固机理,可用于预测和提高NPR锚索锚固系统的性能。     

基于多分辨率数据源镶嵌的大规模地形实时绘制算法

针对不同分辨率的测量地形数据源,提出了镶嵌四叉树模型,用以实现对多分辨率数据源的镶嵌,以及与细节层次(LOD)算法的融合.设计了基于此模型的批LOD算法,给出了相关公式,并设计了一种从CPU到GPU的渐进LOD数据传输方法.分析了镶嵌四叉树的场景浏览模式,设计了基于此模型的双向两级外存数据调度算法,通过水平、高度两个方向的预测和两级数据预取实现数据页的动态更新,实现了三维地形场景的快速构建和实时浏览.实验表明,该算法能够快速处理大规模多分辨率数据源并且能够充分发挥CPU、GPU与I/O的效率,从而在有限环境下进行快速实时绘制.     

CAPP工序图的自动生成

一、引言 工序图的绘制是CAPP中的一个重要组成部分,也是正确实施CAPP设计结果的手段之一。开发工序图绘制软件可以克服手工绘图的弊病,提高工艺设计的效率和正确性,加速实现工艺设计的标准化与现代化,然而,和常规的     

实时监测系统数据处理和动态曲线绘制方法

数据处理和曲线绘制是实时监测系统不可或缺的组成部分.实时监测系统由前端数据采集模块、数据传输通道和后端监测模块组成.分析各种数据传输方式的特点,讨论前端采集模块中数据组织和发送的一般方式,研究后端监测模块中数据处理和曲线绘制的基本流程.针对常规曲线绘制方法效率较低、显示死板等缺点,提出基于内存拷贝数据更新方式的动态曲线绘制方法.使用API相关函数优化曲线绘制程序,使程序执行效率有较大提高,可以保证测试系统实时性要求.     

云南绝版套刻版画的数字模拟合成技术研究

非真实感绘制(Non-Photorealistic Rendering,简称NPR)技术已成为计算机图形学领域最热门的研究方向之一. NPR建立在人类认知的基础上,利用计算机生成不同艺术风格的图形.云南绝版套刻版画是极具云南本土少数民族特色的绘画代表,考察、分析其实际创作过程,揭示其在线条、纹理、色彩运用和创作技法上的特点和规律,对于探索、研究基于图像的云南绝版套刻版画的数字模拟合成关键技术是至关重要的.论文正是基于以上研究,对云南绝版套刻版画中基于线积分卷积LIC的刻痕模拟合成方法、基于多频率噪声场的LIC纹理的混色方法以及刻痕的纹理合成方法进行了初步的探索和实现.     

透明软包装设计稿的绘制技巧

为了使生产厂家得到近似实际效果、逼真的透明软包装设计稿;有时是因为设计还未来得及付诸实施而必须赶着参加各级展评会,需要逼真的透明软包装设计稿时,我们可以采取一些较为特殊的手段或技巧来绘制。根据自己长期的设计绘制经验,其技巧通常有两种,现介绍如下:     

改进的肝脏软组织分割算法及实时绘制

提出了一种基于Graph Cut算法的高精度CT肝脏软组织分割算法,并利用开放运算语言(OpenCL)实现了肝脏软组织实时高效绘制.这种改进的Graph Cut算法分割准确度高,平均正确率达到96.2％,而且利用OpenCL实现的基于八叉树的改进RayCasting算法大大提升了并行绘制速度,得到了近于200倍的加速,...     

Reflector luminaire with high power light-emitting diodes for general lighting

The lighting parameters of LEDs are constantly improving. They should not however be applied directly in general lighting luminaires. Luminous intensity distribution solid of high power LEDs is inappropriate for the uniform lighting of a target surface and produces too high of a luminance for this luminaire for large elevation angles. We analyzed the luminous intensity curves allowing us to achieve the best possible lighting uniformity and limited distribution of the luminous flux. Specially manufactured reflectors with limited height were applied in the designed luminaire model. The application of 30 white and additionally six red diodes in the same luminaire provided the resulting optical radiation with the color temperature of 3702 K and a color rendering index of 81.     

Color considerations in fluorescent solar concentrator stacks

We present modeled results of the luminous and color outputs of a three-layer stack of fluorescent planar concentrators (FPCs). FPCs have the potential to provide sufficient luminous output to illuminate moderate-sized rooms for reasonably-sized collecting areas. It is of course necessary not only that the lumens be sufficient, but also that the light be sufficiently white as to be comfortable. Modeling shows that by use of a stack of three FPCs, one each of violet, green, and red, it is possible to achieve good color rendering and sufficient lighting levels for room illumination.     

An illumination and highlights invariant colour model for image matching

Abstract

Colour can provide critical information for a variety of computer vision tasks such as image matching, object recognition and image retrieval. However, for it to be useful in practice, the colour model used to represent the intrinsic properties of the imaged objects must be insensitive of imaging conditions such as lighting geometry, illumination colour and highlights. In this paper, we present a colour model for image matching and object recognition that is invariant for illumination and highlights. The colour model is defined as the ratios of the colour differences between neighbouring pixels for each colour component. Based on the dichromatic reflection colour model, it is shown that the proposed colour model is invariant to lighting geometry, illumination colour, highlights and diffuse lighting. Experimental results show robust image matching using the proposed colour model on objects that are illuminated under different illumination colours and lighting geometry. The proposed colour model can be used as a prepossessing step for applications where limited or no constraints on the imaging process can be imposed.     

智能优化平台的并行实现及在光学设计中的应用研究

构建了一个智能优化平台,包括粒子群算法、蚁群算法、遗传算法、模拟退火算法、混沌算法和复合形法。该平台包括4个模块,分别是优化问题选择,优化参数设置,优化过程显示以及优化结果输出。将该优化平台应用在RGB LED混合白光的优化设计中,对混合照明模块中发光效率和显色指数进行优化,给出了混合照明模块中发光效率和显色指数的计算方法。     

复杂三维模型的遮挡检测加速算法

在环境光照下渲染复杂三维植被模型时,其自身阴影的计算极为耗时;对它进行预处理是加速运算的一个重要方法。笔者对三维模型各处的自身阴影遮挡测试的预处理计算进行优化,即按坐标轴向对三维模型进行分层,用每层的正交投影图像代替层内的复杂三维结构,使遮挡计算可以快速进行;同时还利用层层合并的技术以节省存储空间。实验结果表明,笔者提出的算法明显提高了三维模型自身阴影遮挡测试的运算速度。     

大功率固态照明用荧光陶瓷研究进展

固态照明具有功率大、亮度高、体积小、节能环保等优点, 已成为21世纪最有前景的照明技术。作为固态照明关键材料, 荧光材料的性能直接决定固态照明器件的显色指数、流明效率和可靠性等技术参数。相较于荧光单晶、荧光玻璃、荧光薄膜及量子阱, 荧光陶瓷因具有优异的热学和光学性质及微观结构易调控等特点, 被认为是综合性能最优的大功率固态照明用荧光材料。未来, 荧光陶瓷将在汽车大灯、户外照明、激光电视、激光影院等领域得到更广泛的应用和发展, 具有广阔的市场前景。本文探讨了大功率固态照明用荧光陶瓷的设计原则, 重点介绍了目前研究相对较多的氧化物荧光陶瓷(主要指钇铝石榴石结构)和氮(氧)化物荧光陶瓷的研究进展, 最后对大功率固态照明用荧光陶瓷的未来发展方向进行了展望。     

Application of high-efficiency light sources

The ever increasing development and marketing of lamps has imposed a greater need upon the lighting designer to understand the different operating characteristics of these various lamps and their application in lighting designs. Luminous efficacy must be treated with great care when used to compare light sources of different types, as it conveys no information about variation of light output with age, colour appearance, colour rendering, mortality or flexibility of control     

Plasma und Dünne Schichten

Plasma and thin films for lighting application Thin films play an important role in the lighting industry. Well known products are reflectors with simple aluminium coating or with dichroic coatings for cold light mirrors. Especially for energy saving applications special halogen bulbs are coated with a transparent hot mirror that increases the overall efficiency up to 50 % while keeping the positive properties of halogen lighting like color, color rendering index, start up performance and others unchanged. Special thin film applications realize color filters, IR filters, UV filters or color conversion filters. All these processes are vacuum processes that work with plasma assistance. The most prominent technologies for cost effective production are the PICVD processes (former development of SCHOTT AG in cooperation with Auer Lighting) and the Microdyn® technology from DSI, Santa Rosa.     

Psychophysical optimization of lighting spectra for naturalness, preference, and chromatic diversity

The optimal spectral profiles of lighting for naturalness, individual preference, and chromatic diversity were estimated with psychophysical experiments in which observers selected illuminants from a set of metamers of D65 to render outdoor and indoor scenes. For naturalness, the illuminant selected was more spectrally structured than daylight and had a low color rendering index. For preference, the illuminant was similar but produced colors a little more saturated. For chromatic diversity, the spectrum was much more structured, with clearly defined peaks in the blue, green, and red spectral regions. These experiments show that light sources with specific structured spectra may have important visual applications in lighting.