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By: Neil E. Cotter |
Triangulation |
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Delaunay triangulation |
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Sphere center point |
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Tool: The following
algorithm finds the center point of an N-dimensional sphere given
N + 1 points, , and is based on the
idea that the center of a sphere lies on bisectors of line segments connecting
points on the perimeter:
i) Determine
vectors, ,
pointing from one point,
,
chosen as an anchor point, toward each other point.
ii) By
dividing by their lengths, normalize the vectors to create unit-length
vectors,
,
pointing from
toward each other point.
iii) Find
the vector, ,
whose projection on each unit-length vector,
, has its endpoint at
the midpoint of the line segment from
to
, (i.e. the projection
of
on
equals
). The projection of
on
is given by the dot
product of
and
.
Group these equations to yield a
matrix formula for .
Since the vectors arise from
points on a sphere, they are not dependent. Thus, the matrix equation is
nonsingular and always solvable.
iv) The center point, , of the circle is
found by summing
and
.