Announcements
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Project 2 code & artifact
due Friday |
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Midterm out tomorrow (check
your email), due next Fri |
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Stereo
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Readings |
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Trucco & Verri, Chapter 7 |
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Read through 7.1, 7.2.1, 7.2.2,
7.3.1, 7.3.2, 7.3.7 and 7.4, 7.4.1. |
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The rest is optional. |
Slide 3
Slide 4
Slide 5
Slide 6
Slide 7
Anaglyphs online
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I used to maintain of list of
sites, but too hard to keep up to date.
Instead, see wikipedia page: |
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http://en.wikipedia.org/wiki/Anaglyph_image |
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Stereo
Stereo
Stereo correspondence
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Determine Pixel Correspondence |
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Pairs of points that correspond
to same scene point |
Stereo image
rectification
Stereo image
rectification
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reproject image planes onto a
common |
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plane parallel to the line
between optical centers |
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pixel motion is horizontal
after this transformation |
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two homographies (3x3
transform), one for each input image reprojection |
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C. Loop and Z. Zhang. Computing
Rectifying Homographies for Stereo Vision. IEEE Conf. Computer Vision and
Pattern Recognition, 1999. |
Stereo matching
algorithms
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Match Pixels in Conjugate
Epipolar Lines |
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Assume brightness constancy |
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This is a tough problem |
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Numerous approaches |
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A good survey and
evaluation: http://www.middlebury.edu/stereo/ |
Your basic stereo
algorithm
Window size
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Smaller window |
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Larger window |
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Stereo results
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Data from University of Tsukuba |
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Similar results on other images
without ground truth |
Results with window
search
Better methods exist...
Stereo as energy
minimization
Stereo as energy
minimization
Depth from disparity
Video View Interpolation
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http://research.microsoft.com/users/larryz/videoviewinterpolation.htm |
Real-time stereo
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Used for robot navigation (and
other tasks) |
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Several software-based
real-time stereo techniques have been developed (most based on simple
discrete search) |
Stereo reconstruction
pipeline
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Steps |
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Calibrate cameras |
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Rectify images |
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Compute disparity |
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Estimate depth |
Active stereo with
structured light
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Project “structured” light
patterns onto the object |
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simplifies the correspondence
problem |
Active stereo with
structured light
Laser scanning
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Optical triangulation |
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Project a single stripe of
laser light |
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Scan it across the surface of
the object |
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This is a very precise version
of structured light scanning |
Laser scanned models
Laser scanned models
Laser scanned models
Laser scanned models
Laser scanned models
Spacetime Stereo