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Sensors 2010, 10(4), 4159-4179; doi:10.3390/s100404159
Article

Non-Linearity Analysis of Depth and Angular Indexes for Optimal Stereo SLAM

* ,
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Received: 22 March 2010; in revised form: 19 April 2010 / Accepted: 20 April 2010 / Published: 26 April 2010
(This article belongs to the Special Issue Motion Detectors)
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Abstract: In this article, we present a real-time 6DoF egomotion estimation system for indoor environments using a wide-angle stereo camera as the only sensor. The stereo camera is carried in hand by a person walking at normal walking speeds 3–5 km/h. We present the basis for a vision-based system that would assist the navigation of the visually impaired by either providing information about their current position and orientation or guiding them to their destination through different sensing modalities. Our sensor combines two different types of feature parametrization: inverse depth and 3D in order to provide orientation and depth information at the same time. Natural landmarks are extracted from the image and are stored as 3D or inverse depth points, depending on a depth threshold. This depth threshold is used for switching between both parametrizations and it is computed by means of a non-linearity analysis of the stereo sensor. Main steps of our system approach are presented as well as an analysis about the optimal way to calculate the depth threshold. At the moment each landmark is initialized, the normal of the patch surface is computed using the information of the stereo pair. In order to improve long-term tracking, a patch warping is done considering the normal vector information. Some experimental results under indoor environments and conclusions are presented.
Keywords: extended Kalman filter; localization; mapping; inverse depth parametrization; non-linearity analysis; 2D warping extended Kalman filter; localization; mapping; inverse depth parametrization; non-linearity analysis; 2D warping
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Bergasa, L.M.; Alcantarilla, P.F.; Schleicher, D. Non-Linearity Analysis of Depth and Angular Indexes for Optimal Stereo SLAM. Sensors 2010, 10, 4159-4179.

AMA Style

Bergasa LM, Alcantarilla PF, Schleicher D. Non-Linearity Analysis of Depth and Angular Indexes for Optimal Stereo SLAM. Sensors. 2010; 10(4):4159-4179.

Chicago/Turabian Style

Bergasa, Luis M.; Alcantarilla, Pablo F.; Schleicher, David. 2010. "Non-Linearity Analysis of Depth and Angular Indexes for Optimal Stereo SLAM." Sensors 10, no. 4: 4159-4179.



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