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Bézier Curve


Bezier

Given a set ofn+1 control pointsP_0,P_1, ...,P_n, the corresponding Bézier curve (or Bernstein-Bézier curve) is given by

 C(t)=sum_(i=0)^nP_iB_(i,n)(t),

whereB_(i,n)(t) is aBernstein polynomial andt in [0,1]. Bézier splines are implemented in theWolfram Language asBezierCurve[pts].

A "rational" Bézier curve is defined by

 C(t)=(sum_(i=0)^(n)B_(i,p)(t)w_iP_i)/(sum_(i=0)^(n)B_(i,p)(t)w_i),

wherep is the order,B_(i,p) are theBernstein polynomials,P_i are control points, and the weightw_i ofP_i is the last ordinate of the homogeneous pointP_i^w. These curves areclosed under perspective transformations, and can representconic sections exactly.

The Bézier curve always passes through the first and last control points and lies within theconvex hull of the control points. The curve is tangent toP_1-P_0 andP_n-P_(n-1) at the endpoints. The "variation diminishing property" of these curves is that no line can have more intersections with a Bézier curve than with the curve obtained by joining consecutive points with straight line segments. A desirable property of these curves is that the curve can betranslated and rotated by performing these operations on the control points.

Undesirable properties of Bézier curves are their numerical instability for large numbers of control points, and the fact that moving a single control point changes the global shape of the curve. The former is sometimes avoided by smoothly patching together low-order Bézier curves. A generalization of the Bézier curve is theB-spline.


See also

B-Spline,NURBSCurve,Spline

Explore with Wolfram|Alpha

References

Bartels, R. H.; Beatty, J. C.; and Barsky, B. A. "Bézier Curves." Ch. 10 inAn Introduction to Splines for Use in Computer Graphics and Geometric Modelling. San Francisco, CA: Morgan Kaufmann, pp. 211-245, 1998.Piegl, L.Fundamental Developments of Computer Aided Geometric Design. San Diego, CA: Academic Press, 1993.Shene, C.-K. "Introduction to Computing with Geometry Notes. Unit 5: Bézier Curves."http://www.cs.mtu.edu/~shene/COURSES/cs3621/NOTES/.

Referenced on Wolfram|Alpha

Bézier Curve

Cite this as:

Weisstein, Eric W. "Bézier Curve."FromMathWorld--A Wolfram Resource.https://mathworld.wolfram.com/BezierCurve.html

Subject classifications

Created, developed and nurtured by Eric Weisstein at Wolfram Research

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