Showing papers by "David G. Lowe published in 2002"

Mobile Robot Localization and Mapping with Uncertainty using Scale-Invariant Visual Landmarks

Abstract: A key component of a mobile robot system is the ability to localize itself accurately and, simultaneously, to build a map of the environment. Most of the existing algorithms are based on laser rang...

Invariant Features from Interest Point Groups

Abstract: This paper approaches the problem of ¯nding correspondences between images in which there are large changes in viewpoint, scale and illumi- nation. Recent work has shown that scale-space `interest points' may be found with good repeatability in spite of such changes. Further- more, the high entropy of the surrounding image regions means that local descriptors are highly discriminative for matching. For descrip- tors at interest points to be robustly matched between images, they must be as far as possible invariant to the imaging process. In this work we introduce a family of features which use groups of interest points to form geometrically invariant descriptors of image regions. Feature descriptors are formed by resampling the image rel- ative to canonical frames de¯ned by the points. In addition to robust matching, a key advantage of this approach is that each match implies a hypothesis of the local 2D (projective) transformation. This allows us to immediately reject most of the false matches using a Hough trans- form. We reject remaining outliers using RANSAC and the epipolar constraint. Results show that dense feature matching can be achieved in a few seconds of computation on 1GHz Pentium III machines.

Global localization using distinctive visual features

Abstract: We have previously developed a mobile robot system which uses scale invariant visual landmarks to localize and simultaneously build a 3D map of the environment In this paper, we look at global localization, also known as the kidnapped robot problem, where the robot localizes itself globally, without any prior location estimate. This is achieved by matching distinctive landmarks in the current frame to a database map. A Hough transform approach and a random sample consensus (RANSAC) approach for global localization are compared, showing that RANSAC is much more efficient. Moreover, robust global localization can be achieved by matching a small sub-map of the local region built from multiple frames.

Vision-based mapping with backward correction

Abstract: We consider the problem of creating a consistent alignment of multiple 3D submaps containing distinctive visual landmarks in an unmodified environment. An efficient map alignment algorithm based on landmark specificity is proposed to align submaps. This is followed by a global minimization using the close-the-loop constraint. Landmark uncertainty is taken into account in the pairwise alignment and the global minimization process. Experiments show that the pairwise alignment of submaps with backward correction produces a consistent global 3D map. Our vision-based mapping approach using sparse 3D data is different from other existing approaches which use dense 2D range data from laser or sonar rangefinders.

An efficient binary corner detector

Abstract: Corner extraction is an important task in many computer vision systems. The quality of the corners and the efficiency of the detection method are two very important aspects that can greatly impact the accuracy, robustness and real-time performance of the corresponding corner-based vision system. In this paper we introduce a fast corner detector based on local binary-image regions. We verify the performance of the proposed method by measuring the repeatability rate under various illumination, scale and motion conditions. Our experimental results show that while the quality of the features is comparable with other conventional methods, ours delivers a faster performance.

Vision-based Mapping with Backward

Abstract: We consider the problem of creating a consistent alignment of multiple 3D submaps containing distinctive visual landmarks in an unmodified environment. An eficient map alignment algorithm based on landmark specificity is proposed to align submaps. This is followed by a global minimization using the close-theloop constraint. Londmark uncertainty is taken into account in the pair-wise alignment and the global minimization process. Experiments show that pair-wise alignment of submaps with backward comction produces a consistent global 3D map. Our vision-based mapping approach using sparse 30 data is different from other existing approaches which use dense 2D range data from laser or sonar rangefinders.