Brian Patrick Williams

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Loop closure detection systems for monocular SLAM come in three broad categories: (i) map-to-map, (ii) image-to-image and (iii) image-to-map. In this paper, we have chosen an implementation of each and performed experiments allowing the three approaches to be compared. The sequences used include both indoor and outdoor environments and single and multiple(More)
Monocular SLAM has the potential to turn inexpensive cameras into powerful pose sensors for applications such as robotics and augmented reality. However, current implementations lack the robustness required to be useful outside laboratory conditions: blur, sudden motion and occlusion all cause tracking to fail and corrupt the map. Here we present a system(More)
Monocular SLAM has the potential to turn inexpensive cameras into powerful pose sensors for applications such as robotics and augmented reality. We present a relocalization module for such systems which solves some of the problems encountered by previous monocular SLAM systems-tracking failure, map merging, and loop closure detection. This module extends(More)
Sequential monocular SLAM systems perform drift free tracking of the pose of a camera relative to a jointly estimated map of landmarks. To allow real-time operation in moderately sized environments, the map is kept quite spare with usually only tens of landmarks visible in each frame. In contrast, visual odometry techniques track hundreds of visual features(More)
In this paper we present a loop closure method for a handheld single-camera SLAM system based on our previous work on relocalization. By finding correspondences between the current image and the map, our system is able to reliably detect loop closures. We compare our algorithm to existing techniques for loop closure in single-camera SLAM based on both(More)
We describe a fast method to relocalise a monocular visual SLAM (simultaneous localisation and mapping) system after tracking failure. The monocular SLAM system stores the 3D locations of visual landmarks, together with a local image patch. When the system becomes lost, candidate matches are obtained using correlation, then the pose of the camera is solved(More)
The integrin α9β1 binds a number of extracellular matrix components to mediate cell adhesion, migration and tissue invasion. Although expressed in a variety of normal human cells including endothelium, it is also expressed in cancer cells. We have previously shown that α9β1 binds VEGF-A to facilitate angiogenesis, an important component of the tumor(More)
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