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This appendix presents the principle of the visual motion estimation technique used for SOLERO. Such a technique allows computing an estimate of the 3D camera motion between two stereo pairs acquisitions1. The six displacement parameters are computed on the basis of a set of 3D point-to-point matches established by tracking the pixels in the image sequence acquired by the robot. The following figure summarizes the approach:
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At time t, a stereo pair is acquired and the Harris corner detector [29] is applied to extract interest points from both images. Then, the point-matching algorithm presented in [35] is used to find correspondences between the interest points in both images. Finally, the cloud of 3D points is obtained using stereovision and a second outlier rejection cycle is performed [36]. Stereovision is only computed for the interest points in order to reduce the computation time.
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At time t+1, a new stereo pair is acquired and the Harris points are again extracted from both images. Then, the correspondences between the interest point extracted in the left images (acquired at time t and t+1) are searched using the same technique as presented in 1.
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The stereovision is used to compute the cloud of 3D points at time t+1.
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Finally, the six displacement parameters between t and t+1 are computed using the least square minimization technique presented in [28].
The approach is robust and provides accurate motion estimates. A precision of 1% can be attained after a 100-m traverse. More details about the visual motion estimation technique can be found in [36]. In particular, the error model for the six displacement parameters is presented. This uncertainty model is used in Chapter 5 for sensor fusion.
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© 2008 Springer-Verlag Berlin Heidelberg
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Lamon, P. (2008). Visual Motion Estimation. In: 3D-Position Tracking and Control for All-Terrain Robots. Springer Tracts in Advanced Robotics, vol 43. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-78287-2_10
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DOI: https://doi.org/10.1007/978-3-540-78287-2_10
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-78286-5
Online ISBN: 978-3-540-78287-2
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