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Interpolation versus approximation spline

Short answer

Interpolation spline passes through all control points, used for digitizing paths. Approximation spline follows shape but only endpoints are guaranteed, used for design. Interpolation can overshoot; approximation gives smoother, predictable shape. Examples: Hermite, cardinal are interpolation; Bezier, B-spline are approximation, with B-spline offering local control.

What is the difference between an interpolation spline and an approximation spline curve?

An interpolation spline passes through all given control points. An approximation spline follows the general shape of the control points but need not pass through them (only some, like the end points).

PointInterpolation splineApproximation spline
Passes through control pointsYes, allNo (usually only end points)
Used forDigitizing drawings, animation pathsDesigning shapes and surfaces
Control of shapeLess intuitive, may overshootSmooth, predictable
Control points known asData pointsControl points forming a control graph
ExamplesHermite, cardinal, Catmull-Rom, natural cubic splineBezier, B-spline
Local changeChanging a point may disturb the curve widelyB-spline gives local control

✓ Answer checked by Claude Opus 5.5 (high effort)

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