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This research paper explores the problem with interpolation using Catmull-Rom spline and proposes a method to interpolate at maximum curvature points in curves. The desired properties include interpolating all control points and ensuring that maximum curvature points only occur at control points. The paper discusses related works and presents an optimization algorithm to achieve curvature interpolation at local maximum points.
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-Curves: Interpolation at Local Maximum Curvature Zhipei Yan1, Stephen Schiller2, Gregg Wilensky3, Nathan Carr2, Scott Schaefer1 1Texas A&M University, 2Adobe Research, 3Adobe
Problems with Interpolation Catmull-Rom Spline
“… human visual system is sensitive to minima and maxima of curvature …” “… all curvature extrema should coincide with the given control points …” [Levien 2009]
Desired Properties • Interpolate all control points • Max curvatures (salient points) only occur at control points ---- No cusps except at control points • Curvature continuous
Clothoid Linear curvature Not continuous with motion of control points
Quadratic Time Parameter Unique from , , and
Computation of Max Curvature Time (1) (2) Substitute (1) into (2) a Unique as a function of , , and
Related works [Schaback 1989]
Related works [Schaback 1989] Use input points as splliting points
Related works [Feng et al. 1995] Interpolate tangent vectors at control points No curvature control.
G2 Condition D C B A C=(1-λ)B+λD E
G2 Joint C D B A E
Inflection Point E • Curvatures have different signs C D B A
Optimization Input
Optimization Initialization
Optimization Iteration 0 pi ci,2 ti ci,0
Optimization Iteration 0 ci+1,1 ci,1 λi ci,0 ci+1,2
Optimization Iteration 0 ci,2 ci,1 ci,0 ti Only is variable.
Step 2 =
Optimization Iteration 1
Optimization Iteration 2
Optimization Iteration 3
Optimization Iteration 4
Optimization Iteration 5