R3^3SGM: Real-time Raster-Respecting Semi-Global Matching for Power-Constrained Systems

Stereo depth estimation is used for many computer vision applications. Though many popular methods strive solely for depth quality, for real-time mobile applications (e.g. prosthetic glasses or micro-UAVs), speed and power efficiency are equally, if not more, important. Many real-world systems rely on Semi-Global Matching (SGM) to achieve a good accuracy vs. speed balance, but power efficiency is hard to achieve with conventional hardware, making the use of embedded devices such as FPGAs attractive for low-power applications. However, the full SGM algorithm is ill-suited to deployment on FPGAs, and so most FPGA variants of it are partial, at the expense of accuracy. In a non-FPGA context, the accuracy of SGM has been improved by More Global Matching (MGM), which also helps tackle the streaking artifacts that afflict SGM. In this paper, we propose a novel, resource-efficient method that is inspired by MGM's techniques for improving depth quality, but which can be implemented to run in real time on a low-power FPGA. Through evaluation on multiple datasets (KITTI and Middlebury), we show that in comparison to other real-time capable stereo approaches, we can achieve a state-of-the-art balance between accuracy, power efficiency and speed, making our approach highly desirable for use in real-time systems with limited power.Comment: Accepted in FPT 2018 as Oral presentation, 8 pages, 6 figures, 4 table

Commissioning ATLAS and CMS with top quarks

The large ttbar production cross-section at the LHC suggests the use of top quark decays to calibrate several critical parts of the detectors, such as the trigger system, the jet energy scale and b-tagging.Comment: 6 pages, 5 figures. Talk given at `V Workshop Italiano sulla Fisica pp a LHC', Perugia, Italy, 30 January - 2 February 200

Clearance of human papillomavirus related anal condylomas after oral and endorectal multistrain probiotic supplementation in an HIV positive male: A case report.

Abstract Go to: Introduction: Here we present the case of a 56-year-old human immunodeficiency virus (HIV)-infected man with multiple anal condylomas and positivity for human papilloma virus (HPV) 18 on anal brushing. Biopsies of the anal mucosa led to the diagnosis of Bowen's disease and a subsequent pelvic magnetic resonance imaging (MRI) scan evidenced multiple reactive lymphoadenopathies and large intra-anal condylomas. The patient was treated with a complete excision of Bowen's lesion and with a 4 months course of supplementation with a high concentration multistrain probiotic formulation administered orally and by rectal instillation with the purpose to reduce local inflammation and to enhance local mucosal immunity. Go to: Conclusion: An MRI performed at the end of the supplementation period evidenced the clearance of the anal condylomas previously described and no evidence of residual lymphadenopathies. Trials are therefore required to confirm this therapeutic possibility and for a better understanding of the mechanisms by which this specific probiotic formulation interacts with local epithelium when administered by the anal route

InfiniTAM v3: A Framework for Large-Scale 3D Reconstruction with Loop Closure

Volumetric models have become a popular representation for 3D scenes in recent years. One breakthrough leading to their popularity was KinectFusion, which focuses on 3D reconstruction using RGB-D sensors. However, monocular SLAM has since also been tackled with very similar approaches. Representing the reconstruction volumetrically as a TSDF leads to most of the simplicity and efficiency that can be achieved with GPU implementations of these systems. However, this representation is memory-intensive and limits applicability to small-scale reconstructions. Several avenues have been explored to overcome this. With the aim of summarizing them and providing for a fast, flexible 3D reconstruction pipeline, we propose a new, unifying framework called InfiniTAM. The idea is that steps like camera tracking, scene representation and integration of new data can easily be replaced and adapted to the user's needs. This report describes the technical implementation details of InfiniTAM v3, the third version of our InfiniTAM system. We have added various new features, as well as making numerous enhancements to the low-level code that significantly improve our camera tracking performance. The new features that we expect to be of most interest are (i) a robust camera tracking module; (ii) an implementation of Glocker et al.'s keyframe-based random ferns camera relocaliser; (iii) a novel approach to globally-consistent TSDF-based reconstruction, based on dividing the scene into rigid submaps and optimising the relative poses between them; and (iv) an implementation of Keller et al.'s surfel-based reconstruction approach.Comment: This article largely supersedes arxiv:1410.0925 (it describes version 3 of the InfiniTAM framework

Real-Time RGB-D Camera Pose Estimation in Novel Scenes using a Relocalisation Cascade

Camera pose estimation is an important problem in computer vision. Common techniques either match the current image against keyframes with known poses, directly regress the pose, or establish correspondences between keypoints in the image and points in the scene to estimate the pose. In recent years, regression forests have become a popular alternative to establish such correspondences. They achieve accurate results, but have traditionally needed to be trained offline on the target scene, preventing relocalisation in new environments. Recently, we showed how to circumvent this limitation by adapting a pre-trained forest to a new scene on the fly. The adapted forests achieved relocalisation performance that was on par with that of offline forests, and our approach was able to estimate the camera pose in close to real time. In this paper, we present an extension of this work that achieves significantly better relocalisation performance whilst running fully in real time. To achieve this, we make several changes to the original approach: (i) instead of accepting the camera pose hypothesis without question, we make it possible to score the final few hypotheses using a geometric approach and select the most promising; (ii) we chain several instantiations of our relocaliser together in a cascade, allowing us to try faster but less accurate relocalisation first, only falling back to slower, more accurate relocalisation as necessary; and (iii) we tune the parameters of our cascade to achieve effective overall performance. These changes allow us to significantly improve upon the performance our original state-of-the-art method was able to achieve on the well-known 7-Scenes and Stanford 4 Scenes benchmarks. As additional contributions, we present a way of visualising the internal behaviour of our forests and show how to entirely circumvent the need to pre-train a forest on a generic scene.Comment: Tommaso Cavallari, Stuart Golodetz, Nicholas Lord and Julien Valentin assert joint first authorshi

Asymptotics of the Packet Speed and Cost in a Mobile Wireless Network Model

An infinite number of nodes move on R^2 according to a random waypoint model; a single packet is traveling towards a destination (located at an infinite distance away) using combinations of wireless transmissions and physical transport on the buffers of nodes. In earlier work [1] we defined two performance metrics, namely, the long-term average speed with which the packet travels towards its destination, and the rate with which transmission cost accumulates with distance covered. Analytical expressions were derived for these metrics, under specific ergodicity assumptions. In this paper we give a precise description of the induced Markov process, we show that it is indeed (uniformly) geometrically ergodic, and that the law of large numbers holds for the random variables of interest. In particular, we show that the two performance metrics are well- defined and asymptotically constant with probability one.European Union’s Horizon 2020 Research and Innovation programme under grant agreement No. 645220 (Road-, Air- and Water-based Future Internet Experimentation - RAWFIE)

Structure and dynamics of the fullerene polymer Li4 C60 studied with neutron scattering

The two-dimensional polymer structure and lattice dynamics of the superionic conductor Li4 C60 are investigated by neutron diffraction and spectroscopy. The peculiar bonding architecture of this compound is definitely confirmed through the precise localisation of the carbon atoms involved in the intermolecular bonds. The spectral features of this phase are revealed through ab-initio lattice dynamics calculations and inelastic neutron scattering experiments. The neutron observables are found to be in very good agreement with the simulations which predict a partial charge transfer from the Li atoms to the C60 cage. The absence of a well defined band associated to one category of the Li atoms in the experimental spectrum suggests that this species is not ordered even at the lowest temperatures. The calculations predict an unstable Li sublattice at a temperature of 200 K, that we relate to the large ionic diffusivity of this system. This specificity is discussed in terms of coupling between the low frequency optic modes of the Li ions to the soft structure of the polymer.Comment: 29 pages, 13 Figure