第
36
卷 第
3
期
测 绘 学 报
Vol. 36 , No. 3
2007
年
8
月 ACTA GEODAETICA et CARTO GRAPHICA SINICA
Aug ,2007
文章编号 :1001 21595
(
2007
)
0320358205 中图分类号 : P208 文献标识码 :A
Delaunay
三角形构网的分治扫描线算法
芮一康
,
王结臣
(
南京大学 地理信息科学系 ,江苏 南京 210093
)
A New Study of Compound Algorithm Based on Sweepline and Divide2and2conquer
Algorithms for Constructing Delaunay Triangulation
RU I Yi
2
kang ,WAN G Jie
2
chen
( Depart ment of Geographic Inf ormation Science , Nanji ng U niversity , N anji ng
210093
, Chi na )
Abstract :As one of the most important DTM model , Delaunay triangulation is widely applied in manifold fields. A
wide variety of algorithms have been proposed to construct Delaunay triangulation , such as divide
2
and
2
conquer , in
2
cremental insertion , trangulation growth , and so on. The compound algorithm is also researched to construct Delau
2
nay triangulation , and prevalently it is mainly based on divide
2
and
2
conquer and incremental insertion algorithms.
This paper simply reviews and assessessweepline and divide
2
and
2
conquer algorithms , based on which a new com
2
pound algorithm is provided after studying the sweepline algorithm seriously. To start with , this new compound al
2
gorithm divides a set of points into several grid tiles with different dividing methods by divide
2
and
2
conquer algo
2
rithm , and then constructs subnet in each grid tile by sweepline algorithm. Finally these subnets are recursively
merged into a whole Delaunay triangulation with a simplified efficient LOP algorithm. For topological structure is im
2
portant to temporal and spatial efficiency of this algorithm , we only store data about vertex and triangle , thus edge
is impliedly expressed by two adjacent triangles. In order to fit two subnets merging better , we optimize some data
structure of sweepline algorithm. For instance , frontline and baseline of triangulation are combined to one line , and
four pointers point to where maximum and minimum of x axis and y axis are in this outline. The test shows that this
new compound algorithm has better efficiency , stability and robustness than divide
2
and
2
conquer and sweepline algo
2
rithms. Especially if we find the right dividing method reply to different circumstance , its superiority is remarkable.
Key words :Delaunay triangulation ; compound algorithm ; sweepline algorithm ; divide
2
and
2
conquer algorithm
摘 要
:Delaunay
三角网作为一种主要的
DTM
表示法
,
具有极其广泛的用途 。基于分治算法和逐点插入法的
合成算法是目前研究较多的用于生成
Delaunay
三角网的合成算法 。简要介绍和评价扫描线算法和分治算法
后 ,提出一种新的基于这两种算法的合成算法 。该方法兼顾空间与时间性能 ,稳定性较高 ,分别较扫描线算法
和分治算法
,
运行效率和鲁棒性更优 。
收稿日期
: 2006
2
06
2
21 ;
修回日期
: 2007
2
02
2
06
基金项目
:
国家自然科学基金
(40401046 )
作者简介 : 芮一康
(
19832
)
,男 ,江苏溧阳人 ,研究生 ,主要从事地理信息系统理论与应用研究。
关键词 :Delaunay 三角网 ;合成算法 ;扫描线算法 ;分治算法
1
引 言
2
维平面域内任意离散点集的不规则三角网
(
TIN2Triangular Irregular Network
)
的 构 建 是
GIS
数据表达 、管理 、集成和可视化的一项重要内
容
,
也是地学分析 、计算机视觉 、表面目标重构 、有
限元分析 、道路
CAD
等领域的一项重要的应用技
术 。在所有生成
TIN
的方法中
,Delaunay
三角网
最优
,
它尽可能避免了病态三角形的出现
,
常常被
用来生成 TIN 。Delaunay 三角网是 Voronoi 图的
直线对偶图
,
即是连接所有相邻的
Voronoi
多边
形的生长中心所形成的三角网 。它有以下两条重
要性质
[1 ]
: 空外接圆性质 ,即由点集所形成的三
角网中
,
每个三角形的外接圆均不包含点集中的