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小木虫论坛-学术科研互动平台 » 专业学科区 » 数学 » 计算数学 » 凹形的平面散乱点作出delaunay网格，怎样把外部多余的delaunay边去掉？急！
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acmuser

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引用回帖:
10楼: Originally posted by chujian77 at 2012-05-15 22:41:15:
我的看法是：
1.给出包含T型区域的三个虚拟点（坐标够大即可），加入到T型区域点集中，进行剖分。
2.找出T型边界与你的剖分网的交点，作为新点加入到原来的点集，重新再做一次Delaunay剖分，基本上可以保证T型区 ...

that may not work, run this matlab script, n is the number of points in the cloud, and R parametrize the virtual points,
function delaunayclouds(n,R)

x=rand(n,1);
y=rand(n,1);

ir = find(x>0.5 & y>0.5);

il = setdiff(1:n,ir);

x=x(il);
y=y(il);

N=length(il);
x(N+1:N+3) = [R, R, -R]';
y(N+1:N+3) = [-R, R, R]';

figure(1);
plot(x,y,'x')
dt = DelaunayTri(x,y);

figure(2);
triplot(dt);
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11楼2012-05-15 23:05:09
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acmuser

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11楼: Originally posted by acmuser at 2012-05-15 23:05:09:
that may not work, run this matlab script, n is the number of points in the cloud, and R parametrize the virtual points,
function delaunayclouds(n,R)

x=rand(n,1);
y=rand(n,1);

ir = find(x ...

I can even add more virtual points, but still no help, in the following, I add 8 virtual points
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12楼2012-05-15 23:14:49
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acmuser

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【答案】应助回帖

引用回帖:
12楼: Originally posted by acmuser at 2012-05-15 23:14:49:
I can even add more virtual points, but still no help, in the following, I add 8 virtual points
16/f5/1582407_1337094886_789.jpg

I think there are some boundary estimate or support estimate algorithm for data clouds in computer graphics, that might help to properly solve this problem. For example,
Rolling-Ball Method For Estimating The Boundary Of The Support Of A Point-Process Intensity (1998)
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.44.3512

But I won't have time to read it through, if you find something simpler, please let us know.
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13楼2012-05-15 23:22:15
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acmuser

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13楼: Originally posted by acmuser at 2012-05-15 23:22:15:
I think there are some boundary estimate or support estimate algorithm for data clouds in computer graphics, that might help to properly solve this problem. For example,
Rolling-Ball Method For E ...

A faster fix might be add some points in the concave corner, see attached, but it is artificial indeed
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14楼2012-05-15 23:38:17
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acmuser

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【答案】应助回帖

use 5 points in the corner
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15楼2012-05-16 00:25:02
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