Download - Smoothly Varying Affine Stitching [CVPR 2011] Ph.D. Student, Chang-Ryeol Lee February 10, 2013
Smoothly Varying Affine Stitching [CVPR 2011]
Ph.D. Student, Chang-Ryeol Lee
February 10, 2013
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Introduction– Motivation– Problem
Related works– Dynamosaics: Video Mosaics with Non-Chronological Time [CVPR
2005]
Proposed method– Smoothly Varying Affine Stitching [CVPR 2011]
Expeirments
Contents
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Motivation– Typical camera FOV: 50˚ X 35˚
Introduction
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Motivation– Typical camera FOV: 50˚ X 35˚– Human FOV: 200˚ X 135˚
Introduction
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Motivation– Typical camera FOV: 50˚ X 35˚– Human FOV: 200˚ X 135˚– Panoramic view: 360˚ X 180˚
Introduction
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Impressive
Introduction
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Problem– Usually generating using rotating the camera around the
center of projection:
Introduction
The mosaic has a natural interpretation in 3D The images are reprojected onto a common plane The mosaic is formed on this plane
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Problem: Changing Camera Center
Introduction
synthetic PP
PP1
PP2
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Problem: Changing Camera Center
Introduction
Pics from Internet
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Dynamosaics: Video Mosaics with Non-Chronological Time [CVPR 2005]– Shmuel Peleg (Hebrew University, Israel)
Motivation– Satellites create panoramas by scanning
• 1D sensor• Rotation & Translation• How can this idea be utilized?
Related works
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Push broom stitching
Related works
t t+1 t+2
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Time-Space Cube– Align the images– Create Push-broom mosaics by combining the image pieces– Different Cuts can create different mosaics
Related works
1 2 3 4 5
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Push broom distortion – x-axis: Orthographic Projection– y-axis: Perspective Projection– y shrinks as Z increases, x doesn’t
Experimental result
Related works
x xy y
fz z
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Smoothly Varying Affine Stitching [CVPR 2011]– Loong-Fah Cheong (NUS)
Work Assumption– Most scenes can be modeled as having smoothly varying depth– A global affine has general shape preservation
Proposed method
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Proposed method System overview
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Proposed method The affine stitching field
0 06 11 ; 2i i iv
a b b
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Proposed method Algorithm to compute stitching field
– Input: 1. M Base image features
2. N Target image features
3. Global affine matrix
– Output:1. Converged affine matrix
0ib
0 jt
convergedA
globalA T
0 0, , , SIFT descriptorsi j x yb t
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Proposed method Algorithm to compute stitching field
– Cost function
– Notation• Affine parameters
• Stitched feature points by
01: 1:log |N ME P A t b Ψ A
(1) (2) (3)2
(4) (5) 0 (6)
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i i iS
i ii i i
SS S S
a a a0
a ab b a
00 I
6 1,...,T
M M A a a i global i a a a 0 06 11 ; 2i i iv
a b b
ia
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Proposed method Algorithm to compute stitching field
– Cost function
– Notation• Robust Gaussian mixture
• Smoothness regularization
201: 1: 0 1:
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| , 2N M
N M j M t tij
P g
t b t b
2
2
'
'min
'v
vd
g
RΨ A
2
22( , )z
g e
z
'
'
v
g
01: 1:log |N ME P A t b Ψ A
: Fourier transform of v
: Fourier transform of Gaussian
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Proposed method Algorithm to compute stitching field
– Cost function
– Minimization by EM style optimization
– Estimated stitching field map
01: 1:log |N ME P A t b Ψ A
T2 1 0 (1) 0 (2)
1
( ) ( [ ] )M
i i ii
v a g
z z b b
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Re-shoot
Applications
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Re-shoot
Applications
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Experiments
Panoramic stitching
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Experiments
Matching
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Thank you!
* This material is based on Raz Nossek‘s Image Registration & Mosaicing.