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<h1><a
href="http://www.geom.uiuc.edu/graphics/pix/Special_Topics/Computational_Geometry/cone.html"><img
src="qh--cone.gif" alt="[cone]" align="middle" width="100"
height="100"></a>qconvex -- convex hull</h1>
<p>The convex hull of a set of points is the smallest convex set
containing the points. See the detailed introduction by O'Rourke
[<a href="index.htm#orou94">'94</a>]. See <a
href="index.htm#description">Description of Qhull</a> and <a
href="qh-eg.htm#how">How Qhull adds a point</a>.</p>
<blockquote>
<dl>
<dt><b>Example:</b> rbox 10 D3 | qconvex <a
href="qh-opto.htm#s">s</a> <a href="qh-opto.htm#o">o</a> <a
href="qh-optt.htm#TO">TO result</a></dt>
<dd>Compute the 3-d convex hull of 10 random points. Write a
summary to the console and the points and facets to
'result'.</dd>
<dt> </dt>
<dt><b>Example:</b> rbox c | qconvex <a
href="qh-opto.htm#n">n</a></dt>
<dd>Print the normals for each facet of a cube.</dd>
<dt> </dt>
<dt><b>Example:</b> rbox c | qconvex <a
href="qh-opto.htm#i">i</a> <a href="qh-optq.htm#Qt">Qt</a></dt>
<dd>Print the triangulated facets of a cube.</dd>
<dt> </dt>
<dt><b>Example:</b> rbox y 500 W0 | qconvex</dt>
<dd>Compute the convex hull of a simplex with 500
points on its surface.</dd>
<dt> </dt>
<dt><b>Example:</b> rbox x W1e-12 1000 | qconvex
<a href="qh-optq.htm#QR">QR0</a></dt>
<dd>Compute the convex hull of 1000 points near the
surface of a randomly rotated simplex. Report
the maximum thickness of a facet.</dd>
<dt> </dt>
<dt><b>Example:</b> rbox 1000 s | qconvex <a
href="qh-opto.htm#s">s</a> <a
href="qh-optf.htm#FA">FA</a> </dt>
<dd>Compute the convex hull of 1000 cospherical
points. Verify the results and print a summary
with the total area and volume.</dd>
<dt> </dt>
<dt><b>Example:</b> rbox d D12 | qconvex <a
href="qh-optq.htm#QRn">QR0</a> <a
href="qh-optf.htm#FA">FA</a></dt>
<dd>Compute the convex hull of a 12-d diamond.
Randomly rotate the input. Note the large number
of facets and the small volume.</dd>
<dt> </dt>
<dt><b>Example:</b> rbox c D7 | qconvex <a
href="qh-optf.htm#FA">FA</a> <a
href="qh-optt.htm#TFn">TF1000</a></dt>
<dd>Compute the convex hull of the 7-d hypercube.
Report on progress every 1000 facets. Computing
the convex hull of the 9-d hypercube takes too
much time and space. </dd>
<dt> </dt>
<dt><b>Example:</b> rbox c d D2 | qconvex <a
href="qh-optq.htm#Qc">Qc</a> <a
href="qh-opto.htm#s">s</a> <a
href="qh-opto.htm#f">f</a> <a
href="qh-optf.htm#Fx">Fx</a> | more</dt>
<dd>Dump all fields of all facets for a square and a
diamond. Also print a summary and a list of
vertices. Note the coplanar points.</dd>
<dt> </dt>
</dl>
</blockquote>
<p>Except for rbox, all of the qhull programs compute a convex hull.
<p>By default, Qhull merges coplanar facets. For example, the convex
hull of a cube's vertices has six facets.
<p>If you use '<a href="qh-optq.htm#Qt">Qt</a>' (triangulated output),
all facets will be simplicial (e.g., triangles in 2-d). For the cube
example, it will have 12 facets. Some facets may be
degenerate and have zero area.
<p>If you use '<a href="qh-optq.htm#QJn">QJ</a>' (joggled input),
all facets will be simplicial. The corresponding vertices will be
slightly perturbed and identical points will be joggled apart.
Joggled input is less accurate that triangulated
output.See <a
href="qh-impre.htm#joggle">Merged facets or joggled input</a>. </p>
<p>The output for 4-d convex hulls may be confusing if the convex
hull contains non-simplicial facets (e.g., a hypercube). See
<a href=qh-faq.htm#extra>Why
are there extra points in a 4-d or higher convex hull?</a><br>
</p>
</p>
<p>The 'qconvex' program is equivalent to
'<a href=qhull.htm#outputs>qhull</a>' in 2-d to 4-d, and
'<a href=qhull.htm#outputs>qhull</a> <a href=qh-optq.htm#Qx>Qx</a>'
in 5-d and higher. It disables the following Qhull
<a href=qh-quick.htm#options>options</a>: <i>d v H Qbb Qf Qg Qm
Qr Qu Qv Qx Qz TR E V Fp Gt Q0,etc</i>.
<p><b>Copyright © 1995-2003 The Geometry Center, Minneapolis MN</b></p>
<hr>
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