Bézier surfaces |
Bézier surfaces are special types of rational surfaces, which use Bernstein bases to represent the polynomial functions. Several types of Bézier surfaces exist.
A rectangular or tensor product Bézier
parametric surface is the image of a map of
the form
where are the control points, and
,
are the Bernstein basis
elements of degree
for the interval
.
A rational tensor-product Bézier surface is constructed as follows:
where are the weights of the control
points (usually
).
The bidegree of the parametrisation is .
A triangular or simplex Bézier parametric
surface is the image of a map of the form
where is the triangle defined by the points
,
are the control
points, and
,
are the
barycentric coordinates of
with respect to
(
).
A rational triangular Bézier surface is constructed similarly as for rectangular surfaces:
where are the weights of the control
points (usually positive).
Here is the well-known example of a teapot model made of 32 pieces
of tensor product Bézier surfaces of bidegre :