面向具有重复结构的大规模CAD模型的快速渲染  

Rapid rendering for large-scale CAD model with repeated structure

作　　者：罗月童[1,2] 周全[1] 周俊[1,2] 丁伟强[1] 甘恮 吴斌 

机构地区：[1]合肥工业大学可视化与协同计算研究室,合肥230009 [2]中国科学院核能安全研究所中子输运理论与辐射安全重点实验室,合肥230031

出　　处：《中国图象图形学报》2018年第1期106-113,共8页Journal of Image and Graphics

基　　金：国家自然科学基金项目(61602146);安徽省科技攻关计划(1604e0302001,1604d0802009);安徽省高等学校自然科学研究重点项目(KJ2016A751)

摘　　要：目的基于普通个人计算机快速渲染大规模计算机辅助设计(CAD)模型仍然是个挑战。针对由少量基本对象按一定规律排布而成的大规模CAD模型——重复结构CAD模型,提出一种快速渲染方法,能够在个人计算机上的快速渲染大规模重复结构CAD模型。方法该方法首先利用重复结构CAD模型的层次结构特征,结合现代GPU的Render-To-Texture的功能进行快速视锥裁剪,节约视锥裁剪时间;然后利用重复结构CAD模型中对象按规律布置的特点,仅对少量基本对象进行面片化,其他对象的面片模型在渲染时根据对象排布规律由基本对象的面片模型实时变换生成,解决大规模CAD模型内存需求过多的问题。结果基于超级蒙卡核模拟软件系统SuperMC,使用典型重复结构模型——HM(hoogenboom-martin)、ADS(accelerator driven sub-critical system)、DCA(deuterium critical assembly)全堆芯CAD模型进行测试,HM、ADS、DCA模型分别由1 114 384,113 952和20 808个实体组成。测试结果表明,裁剪算法能大幅减少待渲染对象数量,渲染速度明显提高,且模型规模越大,本文方法优势越明显,在远视角的情况下提升效果最为突出,能提升3倍左右;结论针对任意大规模CAD模型的快速渲染仍然是一个挑战,但本文针对重复结构CAD模型的特点,针对性地提出一套专用渲染策略,在个人计算机上实现大规模重复结构CAD模型的快速渲染。使用多个典型重复结构模型——反应堆全堆芯模型进行测试,测试结果表明了本文方法的有效性。Objective CAD （Computer Aided Design） is widely applied in many areas; however, rapidly rendering a large- scale CAD model on a commodity personal computer remains a challenge. Many researchers have been working on general- purpose rendering methods for large-scale models, and some have evaluated special-purpose rendering methods by utilizing the features of target models. The presented method belongs to special-purpose rendering methods. The method is designed to render a large-scale repeated-structure model, which is constructed by arranging several basic objects according to certain rules. Method Tree is often used to represent hierarchical CAD models. Two special nodes are defined to represent repeat- ed-structure CAD models. One is used to represent basic objects, and the other is used for the ＂arrangement rule＂ of basic objects. A large-scale repeated-structure CAD model can thus be represented with a small-scale tree. CAD models cannot usually be rendered directly ; they are to be converted into facets for rendering. However, the corresponding facet models for large-scale CAD models are extremely large to be stored and processed, which is a significant problem for large CAD model rendering. Repeated-structure CAD models are constructed by arranging few basic objects according to some rules. There- fore, the presented method solves the problem by generating and storing only the facets of basic objects, and the facets of all other objects are generated during the rendering process according to arrangement rules. Basic objects are less than the total objects in CAD models, and facets of basic objects are thus easy to generate and store. The running time of the view-frus- tum culling algorithm is proportional to facet number. For a large number of facets involved in large-scale CAD model ren- dering, the efficiency of the view-frustum culling algorithm is necessary to improve. Instead of processing facets directly, the presented method culls objects layer by layer by utilizing the hierarchical structur

关 键 词：大规模CAD模型快速渲染 重复结构 视锥裁剪 渲染到纹理 

分 类 号：TP391.72[自动化与计算机技术—计算机应用技术]