雕塑实体造型系统中连续变化求交问题的相关技术研究

发布时间：2018-05-25 14:43

本文选题：计算机辅助几何设计 + 曲面求交　；参考：《浙江大学》2003年博士论文

【摘要】： 曲面求交技术一直是计算机辅助几何设计中实体造型的核心算法，本文对雕塑实体造型系统中出现的连续变化曲面——等距曲面和运动曲面求交问题进行了深入的研究，讨论了基于雕塑实体模型的连续实体布尔操作运算。作者首先回顾了实体造型系统中实体表示模型的发展历程以及它们各自的特点，阐述了计算机辅助设计中曲面求交技术的分类、发展历史和它们各自的优缺点，并对连续变化曲面求交的应用背景进行了综述。等距曲面和运动曲面在CAD／CAM领域中有着重要的应用，，在一些时间敏感场合例如数控加工动态仿真，等距曲面和运动曲面等连续变化曲面求交运算已成为这些系统的计算瓶颈，连续变化曲面求交问题的通常解法是采用曲面求交算法反复迭代计算交线，没有考虑连续变化曲面交线之间的相似性进行求交简化，效率上一直不能有很大的提高。本文通过对等距曲面交线结构进行了大量的分析，从交线的形成和演化过程，揭示了等距曲面的交线拓扑结构和曲面上特征点之间存在着本质的联系，提取等距曲面不同Offset距离交线环的相关性，并使用特征点来标识交线环的拓扑信息，成功地将拓扑信息和跟踪法相结合，设计了一种等距曲面求交优化算法。算法通过在曲面交线拓扑信息的指导下，确定交线分支初始点的求取策略，根据交线环拓扑结构，动态调整交线环的局部搜索策略，从而提高了交线环求解的演化效率。新算法在已知交线环拓扑信息的情况下不仅自动解决了常规算法中难以克服的拓扑连接错误，而且对于常规算法中难以克服的多分支奇异点等情况都能正确处理。在分析了等距曲面求交问题的基础上，本文针对实体造型系统中较常用的运动曲面求交问题也进行了研究，本文结合运动曲面自身的特点，找到了表征运动曲面不同运动瞬间交线环演化规律的拓扑特征点，并提出了运动曲面优化求交算法。在分析以往雕塑实体模型数据结构的基础上，本文给出了一个运动雕塑实体布尔操作算法，在保证鲁棒性和精确性的同时确保高效率是算法的目标。雕塑实体模型通过裁剪曲面片和半边数据结构来表达几何和拓扑信息。结合前面提到的连续变化曲面求交算法，在原有雕塑实体布尔操作的基础上，把连续变化曲面求交技术应用到运动雕塑实体布尔操作中，利用连续运动中曲面交线相似性进行求交简化，加快布尔操作计算时间，加入对连续运动实体的特殊处理，提升了运动雕塑实体布尔操作的计算效率。同时采用层次求交和交线跟踪的方法，保证曲面片分割和区域分类的一致性，从而克服了实践中常见的退化情况。在该算法的基摘要础上，本文也给出了扩展到非正则模型的布尔操作算法。为了在某些限时操作下得到实时交互的速度，在运动雕塑实体布尔操作的基础上，本文进一步提出了一个运动雕塑实体模型布尔操作的分布式并行算法。实现了一个基于异构多机型的局域网的分布式运动雕塑实体布尔操作并行算法，提出一个常用分布式雕塑实体布尔操作的并行模型，并在此基础上对算法进行改造，实现了运动实体的分布式布尔操作。算法的主要工作是在串行算法的基础上飞提取各个阶段的并行性，并对于不同的并行任务采用不同的负载均衡手段，将任务分布到局域网上不同的处理器节点，以获得实时计算效果。对于常见的网络出错情况，算法也进行了相应的处理，确保任务的最终完成。
[Abstract]:Surface intersection technology has been the core algorithm of solid modeling in computer aided geometric design . In this paper , the problem of continuous change of curved surface , isometric surface and moving curved surface in the modeling system of sculptural entities is studied deeply , and the continuous entity Boolean operation based on the sculpture entity model is discussed .

Firstly , the author reviews the development course of the entity representation model in the solid modeling system and their respective characteristics , expounds the classification , development history and their respective advantages and disadvantages of the surface intersection technology in the computer aided design , and summarizes the application background of the intersection of the continuous changing curved surface .

In this paper , we have made a great deal of analysis on the intersection line structure of an isometric curved surface , and then used the feature points to identify the intersection of the intersection loops .

On the basis of analyzing the intersection problem of isometric curved surface , this paper studies the intersection problem of moving curved surface which is commonly used in solid modeling system . In this paper , we find the topological feature points that characterize the evolution law of the instantaneous intersection ring of the moving curved surface in combination with the characteristics of the moving curved surface , and put forward the algorithm of optimizing the moving curved surface .

On the basis of analyzing the data structure of the traditional sculpture entity model , this paper presents a Boolean operation algorithm of motion sculpture , which ensures the efficiency is the object of the algorithm while ensuring the robustness and accuracy .

pick up

In this paper , the Boolean operation algorithm extended to the non - regular model is also given in this paper .

In order to get the speed of real - time interaction under certain limited - time operation , the basis of the Boolean operation of the moving sculpture entity

In this paper , a distributed parallel algorithm for Boolean operation of motion sculpture entity model is presented in this paper .

a distributed motion sculpture entity Boolean operation parallel algorithm based on heterogeneous multi - model local area network is presented ,

A parallel model of Boolean operation of a common distributed sculpture entity is proposed , and the algorithm is modified on the basis of the parallel model .

In this paper , the distributed Boolean operation of the moving entity is realized , and the main work of the algorithm is based on the serial algorithm .

fly

the parallelism of each stage is extracted , and different load balancing means are adopted for different parallel tasks ,

traffic is distributed to different processor nodes on the local area network to obtain real - time computing effects . For common networks

The algorithm also performs corresponding processing to ensure the final completion of the task .
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2003
【分类号】：TP391.7

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