Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Functional Equations Find parametric midpoint of a function F x x 0 1 F G ( F ( x ), F ( x )) 0 1 2 Example: F ( x ) = cos( m x+b ) ( 1 F ( x ))( 1 F ( x )) ( 1 F ( x ))( 1 F ( x )) x x 0 1 0 1 0 1 F 2 2
Other Averaging Rules Function Averaging Rule 2 2 x x F ( x ) F ( x ) F ( ) 0 1 0 1 F ( x ) x 2 2 (( ( ) ( )) / 2 ( ) ( ) F x F x F x F x x x 2 F ( ) 0 1 0 1 F ( x ) x 0 1 2 2 x x F ( x ) F ( x ) F ( ) 0 1 0 1 1 F ( x ) 2 ( F ( x ) F ( x )) / 2 x 0 1 x x F ( x ) F ( x ) F ( ) 0 1 0 1 1 F ( x ) 2 2 2 2 x ( F ( x ) F ( x ) ) / 2 0 1 ( ( ) 1 )( ( ) 1 ) ( ( ) 1 )( ( ) 1 ) F x F x F x F x x x F ( x ) cosh( x ) F ( ) 0 1 0 1 0 1 2 2
Non-linear Maps Given n R F: 1-1 function on S: subdivision scheme ˆ 1 S F S F Then ˆ 1 S F S F ˆ 0 0 S p p S F p F p
Non-linear Maps Given n R F: 1-1 function on : subdivision scheme S S S 2 S 1 d ˆ 1 S F S F Then ˆ 1 1 1 S F S F F S F F S F 2 1 d
Non-linear Maps Example ˆ 1 1 1 S F S F F S F F S F 2 1 d F ( x ) Lane-Reisenfeld ˆ j S ( p ) p 1 S ( p ) F ( F ( p )) 1 j 1 j j 2 2 ˆ 1 1 p p F ( p ) F ( p ) j j 1 j j 1 S ( p ) S ( p ) F ( ) i 1 j i 1 j 2 2
Non-linear Maps Example ˆ 1 1 1 S F S F F S F F S F 2 1 d x Lane-Reisenfeld F ( x ) e ˆ j j S ( p ) p S ( p ) p 1 j 1 j 2 2 ˆ p p j j 1 S ( p ) S ( p ) p p i 1 j 2 i 1 j j j 1
Smoothness and Interpolation Given n R F : 1-1 function on S : subdivision scheme ˆ 1 S F S F Then ˆ ˆ 0 k n 0 min( k , n ) S ( p ) : C & F : C S ( p ) : C ˆ S :interpolatory :interpolatory S
Example Four-Point [Dyn et al. 1987]
Example Four-Point [Dyn et al. 1987] 9 9 16 16 1 1 16 16
Example Four-Point [Dyn et al. 1987]
Example Four-Point [Dyn et al. 1987]
Example Four-Point [Dyn et al. 1987]
Example Four-Point [Dyn et al. 1987]
Example Four-Point [Dyn et al. 1987] Mobius Transform
Example Four-Point [Dyn et al. 1987] Mobius Transform
Example Four-Point [Dyn et al. 1987] Mobius Transform
Example Four-Point [Dyn et al. 1987] Mobius Transform
Example Four-Point [Dyn et al. 1987] Mobius Transform
Geometric Properties Properties: convex-hull, variation diminishing z Linear F ( z ) e
Geometric Interpretation Modify geodesics so that the properties hold ˆ ˆ ˆ ˆ 1 1 D ( P , Q ) Dist ( F ( P ), F ( Q )) Euclidean F 1 F
Geometric Interpretation A set C is convex w.r.t. the geodesics G if the geodesic connecting any two points in C lies completely within C
Geometric Interpretation A set C is convex w.r.t. the geodesics G if the geodesic connecting any two points in C lies completely within C
Geometric Interpretation A set C is convex w.r.t. the geodesics G if the geodesic connecting any two points in C lies completely within C
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Intersection If convex hulls of the control points do not 1) intersect, then the curves do not intersect If each curve is approximately a straight 2) line, intersect those lines; else subdivide
Computing Convex Hulls Non-linear hulls may be curved and difficult to compute If is monotonic, we can compute a F ' t ( ) simple piecewise linear approximation
Computing Convex Hulls Non-linear hulls may be curved and difficult to compute If is monotonic, we can compute a F ' t ( ) simple piecewise linear approximation
Computing Convex Hulls Non-linear hulls may be curved and difficult to compute If is monotonic, we can compute a F ' t ( ) simple piecewise linear approximation
Computing Convex Hulls Non-linear hulls may be curved and difficult to compute If is monotonic, we can compute a F ' t ( ) simple piecewise linear approximation
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