Uncalibrated Stereo Rectification for

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Uncalibrated Stereo Rectification for Automatic
3D Surveillance
Ser-Nam Lim, Anurag Mittal, Larry S. Davis and
Nikos Paragios
Results
Why does it work?
Stereo Rectification

• PlaneParallax effect
• Residual parallax displacement field in the
  plane-aligned image is a displacement along a
  line geometrically identical to the epipolar line
  in the reference view

• Pre-processing step to simplify stereo matching
• Transforms the epipole to the point at infinity,
  conjugate epipolar lines are aligned horizontally
• Current issues
• Image distortion
• Accuracy
• Epipole in image

Automatic 3D Surveillance with Moving Cameras

• Stereo used in surveillance for purposes such as
  3D reconstruction, illumination-invariant
  background subtraction
• Cameras are dynamically positioned to optimize
  performance
• Reverse polarity of conjugate epipolar lines is a
  problem when moving cameras are used

Rectification steps

• Determine Fundamental Matrix
• Determine epipoles octant
• Minimize loss of pixel information
• Bresenhams line scanning algorithm
• Distance between consecutive epipolar
• lines lt 1 pixel
• Appropriate starting position of each
• rectified image row

Concluding Remarks

• Stereo rectification for automatic 3D
  surveillance
• Handles moving camera, therefore allows camera
  re-positioning to optimize system performance
• Resolved common rectification issues

Basic Idea of Our Approach

• Exploit presence of planes in the scene
• Aligning plane in second view with homography
• Conjugate epipolar lines become geometrically
  identical
• Add conjugate epipolar lines to the final
  rectified pair line by line

References

• M. Pollefeys. R. Koch and L. VanGool, A Simple
• and Efficient Rectification Method for General
  Motion, ICCV99