[vtkusers] insphere radius of a tetrahedron

[Will Schroeder]

The inscribed sphere radius is not directly related to the circumsphere. In 
the limiting case (where the tetra approaches flat) the insphere r ~ 0, 
while the circumsphere R -> infinity. Go to 
http://mathforum.org/dr.math/faq/formulas/faq.polyhedron.html#tetrahedron 
for the equations. If you code it up, please let's add it into vtkTetra as 
a companion to   "static double Circumsphere(double  p1[3], double p2[3], 
double p3[3], double p4[3], double center[3]);" The ratio of r/R is a good 
measure of the quality of the tetrahedron, and is used by finite element 
analysts.
Will


At 06:50 AM 4/25/2002 -0500, Randy Heiland wrote:
>If you have the outer, isn't the inner just 1/3 of it?
>
>Randy
>
>------------------------
>Hi everybody,
>
>I would like to calculate the insphere radius of a tetrahedron...I used
>Circumsphere() function for the outer radius...
>
>How can I compute easily the inner sphere radius of a tetrahedron in VTK or
>mathematically using VTK....
>
>I would be greatful if you help me.....
>
>Thanks....
>
>Rupi
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