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Robotics 2017, 6(4), 38;

Cloud-Edge Suppression for Visual Outdoor Navigation

Computer Engineering Group, Faculty of Technology, Bielefeld University, D-33615 Bielefeld, Germany
Author to whom correspondence should be addressed.
Received: 25 September 2017 / Revised: 22 November 2017 / Accepted: 27 November 2017 / Published: 3 December 2017
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Outdoor environments pose multiple challenges for the visual navigation of robots, like changing illumination conditions, seasonal changes, dynamic environments and non-planar terrain. Illumination changes are mostly caused by the movement of the Sun and by changing cloud cover. Moving clouds themselves also are a dynamic aspect of a visual scene. For visual homing algorithms, which compute the direction to a previously visited place by comparing the current view with a snapshot taken at that place, in particular, the changing cloud cover poses a problem, since cloud movements do not correspond to movements of the camera and thus constitute misleading information. We propose an edge-filtering method operating on linearly-transformed RGB channels, which reliably detects edges in the ground region of the image while suppressing edges in the sky region. To fulfill this criterion, the factors for the linear transformation of the RGB channels are optimized systematically concerning this special requirement. Furthermore, we test the proposed linear transformation on an existing visual homing algorithm (MinWarping) and show that the performance of the visual homing method is significantly improved compared to the use of edge-filtering methods on alternative color information. View Full-Text
Keywords: visual navigation; outdoor; visual homing; warping; edge detection; sky segmentation; color transformation visual navigation; outdoor; visual homing; warping; edge detection; sky segmentation; color transformation

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Hoffmann, A.; Möller, R. Cloud-Edge Suppression for Visual Outdoor Navigation. Robotics 2017, 6, 38.

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