convexHull

Class: DelaunayTri

(Not recommended) Convex hull

Compatibility

Note

convexHull(DelaunayTri) is not recommended. Use convexHull(delaunayTriangulation) instead.

DelaunayTri is not recommended. Use delaunayTriangulation instead.

Syntax

K = convexHull(DT) [K AV] = convexHull(DT)

Description

K = convexHull(DT) returns the indices into the array of points DT.X that correspond to the vertices of the convex hull.

[K AV] = convexHull(DT) returns the convex hull and the area or volume bounded by the convex hull.

Input Arguments

`DT`	Delaunay triangulation.

Output Arguments

`K`	If the points lie in 2-D space, `K` is a column vector of length `numf`. Otherwise `K` is a matrix of size `numf`-by-`ndim`, `numf` being the number of facets in the convex hull, and `ndim` the dimension of the space where the points reside.
`AV`	The area or volume of the convex hull.

Examples

Example 1

Compute the convex hull of a set of random points located within a unit square in 2-D space.

x = rand(10,1)
y = rand(10,1)
dt = DelaunayTri(x,y)
k = convexHull(dt)
plot(dt.X(:,1),dt.X(:,2), '.', 'markersize',10); hold on;
plot(dt.X(k,1),dt.X(k,2), 'r'); hold off;

Example 2

Compute the convex hull of a set of random points located within a unit cube in 3-D space, and the volume bounded by the convex hull.

X = rand(25,3)
dt = DelaunayTri(X)
[ch v] = convexHull(dt)
trisurf(ch, dt.X(:,1),dt.X(:,2),dt.X(:,3), 'FaceColor', 'cyan')

More About

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Convex Hull

The convex hull of a set of points X is the smallest convex region containing all of the points of X.

Documentation