Using Delaunay triangulation to approximate the area

Hi,

I try to use delaunay triangulation but it also connected the boundary point

As you an see the X shape, thats what I wanted only, not the square too.

thank you

[John D'Errico]

Why did you need to ask this question twice? As I showed the last time you asked the question, you cannot use a Delaunay triangulation to do what you want, at least not without understanding how to code an alpha shape.

[madhan ravi]

please don‘t ask the same question twice , this discourages the answerers who answer the question

Answer 1

[KSSV]

Taking the code from John D'Errico. answer here

xy = rand(5000,2);
k = (sqrt(sum((xy - [1 .5]).^2,2)) < 0.3) | ...
    (sqrt(sum((xy - [0 .5]).^2,2)) < 0.3) | ...
    (sqrt(sum((xy - [0.5 1]).^2,2)) < 0.3) | ...
    (sqrt(sum((xy - [0.5 0]).^2,2)) < 0.3);
xy(k,:) = [];
x = xy(:,1) ; y = xy(:,2) ; 
idx = boundary(x,y) ;  % gives boundary 
plot(x,y,'.r')
hold on
plot(x(idx),y(idx),'b')
A = polyarea(x(idx),y(idx))