Exponential Quasi-interpolatory SubdiviExponential Quasi-interpolatory Subdivision Schemesion Scheme
Yeon Ju Lee and Jungho Yoon Yeon Ju Lee and Jungho Yoon
Department of Mathematics, Ewha W. University Seoul, Korea
Exponential quasi-interpolatory s.s.
ContentsContents
Subdivision scheme – several type of s.s. Quasi-interpolatory subdivision scheme Construction Smoothness & accuracy Example Exponential quasi-interpolatory subdivision scheme Construction Smoothness Example
Exponential quasi-interpolatory s.s.
Subdivision schemeSubdivision scheme
Useful method to construct smooth curves and surfaces in CAGD
The rule :
Exponential quasi-interpolatory s.s.
Subdivision schemeSubdivision scheme
Rule :
Interpolatory s.s. & Non-interpolatory s.s
Stationary s.s. & Non-stationary s.s
Exponential quasi-interpolatory s.s.
B-spline subdivision schemeB-spline subdivision scheme
It has maximal smoothness Cm-1 with minimal support. It has approximation order only 2 for all m. Cubic-spline :
Exponential quasi-interpolatory s.s.
Interpolatory subdivision schemeInterpolatory subdivision scheme
4-point interpolatory s.s. :
The Smoothness is C1 in some range of w. The Approximation order is 4 with w=1/16.
Exponential quasi-interpolatory s.s.
Goal
We want to construct a new scheme
which has good smoothness and approximation order.
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme Construction
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme Advantage L : odd (L+1,L+2)-scheme. So in even pts case, it has
tension. L : even (L+2,L+2)-scheme. It has tension in both
case.
This scheme has good smoothness.
It has approximation order L+1.
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme
The mask set of cubic case
In cubic case, the mask can reproduce polynomials up to degree 3.
odd case : use 4-pts
even case : use 5-pts with tension v
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme
Various basic limit function which start with
-6 -4 -2 0 2 4 6-0.2
0
0.2
0.4
0.6
0.8
1
1.2
v=0
Limit functions
v=0.02
v=0.04
v=0.06
Cubic Spline
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme
Comparison of schemes which use cubic
Cubic-spline 4-pts interp. s.s. Sa
Where L=3
Support of limit ftn [-2, 2] [-3, 3] [-4, 4]
MaximalSmoothnes
sC2 C1 C3
Approximation
Order2 4 4
Exponential quasi-interpolatory s.s.
ExampleExample
1 2 3 4 5 6 70.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
v=0
v=0.02
v=0.04
v=0.06
Cubic-spline
Exponential quasi-interpolatory s.s.
Comparison with some Comparison with some exampleexample
Example < cubic-spline > < Sa >
E=0.8169 E=0.1428
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8-10
-5
0
5
10
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.80
0.2
0.4
0.6
0.8
1
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8-10
-5
0
5
10
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.80
0.05
0.1
0.15
0.2
Exponential quasi-interpolatory s.s.
Quasi-interpolatory subdivision schemeQuasi-interpolatory subdivision scheme
General caseL Mask set Sm
.Range of tension
3 O=[-1/16,9/16,9/16,-1/16] E= [-v, 4v,1-6v,4v,-v]
C3 0.0208<v<0.0404
4 O=[-v,–77/2048+5v,385/512-10v, 385/1024+10v,-55/512-5v,35/2048+v] E(i)=O(7-i) for i=1:6
C3 -0.0106<v<-0.0012
5 O=[3,–25,150,150,–25,3]/256] E=[-v,6v,–15v,1+20v,-15v,6v,-v]
C4 -0.0084<v<-0.0046
6 O=[-v,385/65536+7v,–2079/32768-21v, 51975/65536+35v,5775/16384-35v, -7245/65536+21v,945/32768-7v,-231/65536+v] E(i)=O(9-i) for i=1:8
C4 0.0007<v<0.0017
7 O=[-5,49,–245,1225,1225,–245,49,–5]/2048 E=[-v, 8v,–28v,56v,1-70v,56v,–28v,8v,–v]
C5 0.0012<v<0.0015
Exponential quasi-interpolatory s.s.
Exponential quasi-interpolatory s.s.Exponential quasi-interpolatory s.s. Construction
Exponential quasi-interpolatory s.s.
Analysis of non-stationary Analysis of non-stationary s.s.s.s.
Exponential quasi-interpolatory s.s.
Exponential quasi-interpolatory s.s.Exponential quasi-interpolatory s.s.
Exponential quasi-interpolatory s.s.
Exponential quasi-interpolatory s.s.Exponential quasi-interpolatory s.s.
Example
E=7.7716e-016 E=0.1434
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8-10
-5
0
5
10
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.80
0.05
0.1
0.15
0.2
-1 -0.5 0 0.5 1-1
-0.5
0
0.5
1
Exponential quasi-interpolatory s.s.
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