Documentation

This is machine translation

Translated by Microsoft
Mouseover text to see original. Click the button below to return to the English verison of the page.

Note: This page has been translated by MathWorks. Please click here
To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.

convhull

    Note:   Qhull-specific options are no longer supported. Remove the OPTIONS argument from all instances in your code that pass it to convhull.

Syntax

K = convhull(X,Y)
K = convhull(X,Y,Z)
K = convhull(X)
K = convhull(...,'simplify', logicalvar)
[K,V] = convhull(...)

Description

K = convhull(X,Y) returns the 2-D convex hull of the points (X,Y), where X and Y are column vectors. The convex hull K is expressed in terms of a vector of point indices arranged in a counterclockwise cycle around the hull.

K = convhull(X,Y,Z) returns the 3-D convex hull of the points (X,Y,Z), where X, Y, and Z are column vectors. K is a triangulation representing the boundary of the convex hull. K is of size mtri-by-3, where mtri is the number of triangular facets. That is, each row of K is a triangle defined in terms of the point indices.

K = convhull(X) returns the 2-D or 3-D convex hull of the points X. This variant supports the definition of points in matrix format. X is of size mpts-by-ndim, where mpts is the number of points and ndim is the dimension of the space where the points reside, 2 ≦ ndim ≦ 3. The output facets are equivalent to those generated by the 2-input or 3-input calling syntax.

K = convhull(...,'simplify', logicalvar) provides the option of removing vertices that do not contribute to the area/volume of the convex hull, the default is false. Setting 'simplify' to true returns the topology in a more concise form.

[K,V] = convhull(...) returns the convex hull K and the corresponding area/volume V bounded by K.

Visualization

Use plot to plot the output of convhull in 2-D. Use trisurf or trimesh to plot the output of convhull in 3-D.

Examples

collapse all

xx = -1:.05:1;
yy = abs(sqrt(xx));
[x,y] = pol2cart(xx,yy);
k = convhull(x,y);
plot(x(k),y(k),'r-',x,y,'b*')

More About

collapse all

Convex Hull

convhull returns the convex hull of a set of points in 2-D or 3-D space.

Introduced before R2006a

Was this topic helpful?