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Registration algorithm based
on image matching
for outdoor AR system
with fixed viewing position
IEE Proc.-Vis. Image Signal Process., Vol. 153,
No. 1, February 2006
Speaker：Po-Hung Lai
Date：2010/4/13
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Outline
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Introduction
Principle
Architecture of outdoor AR system
Experiments
Conclusions
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Introduction
• Augmented reality
– characteristic
• joints virtual object with realistic environments
• look like a real part of the scene
– example
• visual medical surgery
• digital reconstruction of historic sites
• military
• industry
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Introduction
– registration three steps
• positioning
• rendering
• merging
– key problem is image registration
• direction-tracking equipment
• computer vision
• hybrid registration
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Introduction
– other problem：placement of markers
• very sensitive to outdoor lighting
• randomly hidden from view
• place markers in many outdoor applications
– improvement
• a fixed-viewing-position outdoor AR system
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Introduction
• fixed-viewing-position outdoor AR system
– Fourier–Mellin-based
– Requires a set of prestored reference images
– more accurate and robust
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Principle
• 2.1 a fixed-viewing -position outdoor AR
system
– pin-hole model
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Principle
– camera
– Registration problem
• translation, rotation, scale changes
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Principle
• Phase correlation technique for detection of
translation
– Let f s and f r are two images
– f s , f r are the corresponding Fourier transforms
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Principle
– cross-spectrum of f s and f r
– inverse Fourier transform of R
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Principle
• Phase correlation technique for detection of
translation and rotation
– According to the property of a Fourier
transformation
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Principle
– Fourier –Mellin transform and detection of scale,
rotation, and translation (R, S, T):
– Fourier transforms
fs
and f r are related
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Principle
– Let Gs and Gr denote the magnitude spectra
– Let H s and H r denote the transforms of Gs and Gr
converted
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Principle
– log transform for
in the polar coordinates
– Let Qs and Qr denote the corresponding transform
of H s and H r
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Principle
– Fourier transform of a log-polar map
equivalent Fourier–Mellin transform
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Principle
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Architecture of outdoor AR system
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Architecture of outdoor AR system
• with the Fourier–Mellin transform algorithm
– accurate orientation
– 6 degrees of freedom of camera
– joints virtual object with realistic
environments
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Architecture of outdoor AR system
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Experiments
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Conclusions
• difficult 3-D image registration can be
simplified to a 2-D image registration
• intrusive object is not significant, registration
result is also correct
• algorithm cannot be performed in real time on
a computer
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