5,821 research outputs found
Efficient 2D-3D Matching for Multi-Camera Visual Localization
Visual localization, i.e., determining the position and orientation of a
vehicle with respect to a map, is a key problem in autonomous driving. We
present a multicamera visual inertial localization algorithm for large scale
environments. To efficiently and effectively match features against a pre-built
global 3D map, we propose a prioritized feature matching scheme for
multi-camera systems. In contrast to existing works, designed for monocular
cameras, we (1) tailor the prioritization function to the multi-camera setup
and (2) run feature matching and pose estimation in parallel. This
significantly accelerates the matching and pose estimation stages and allows us
to dynamically adapt the matching efforts based on the surrounding environment.
In addition, we show how pose priors can be integrated into the localization
system to increase efficiency and robustness. Finally, we extend our algorithm
by fusing the absolute pose estimates with motion estimates from a multi-camera
visual inertial odometry pipeline (VIO). This results in a system that provides
reliable and drift-less pose estimation. Extensive experiments show that our
localization runs fast and robust under varying conditions, and that our
extended algorithm enables reliable real-time pose estimation.Comment: 7 pages, 5 figure
Single Image Human Proxemics Estimation for Visual Social Distancing
In this work, we address the problem of estimating the so-called "Social
Distancing" given a single uncalibrated image in unconstrained scenarios. Our
approach proposes a semi-automatic solution to approximate the homography
matrix between the scene ground and image plane. With the estimated homography,
we then leverage an off-the-shelf pose detector to detect body poses on the
image and to reason upon their inter-personal distances using the length of
their body-parts. Inter-personal distances are further locally inspected to
detect possible violations of the social distancing rules. We validate our
proposed method quantitatively and qualitatively against baselines on public
domain datasets for which we provided groundtruth on inter-personal distances.
Besides, we demonstrate the application of our method deployed in a real
testing scenario where statistics on the inter-personal distances are currently
used to improve the safety in a critical environment.Comment: Paper accepted at WACV 2021 conferenc
Hand gesture recognition with jointly calibrated Leap Motion and depth sensor
Novel 3D acquisition devices like depth cameras and the Leap Motion have recently reached the market. Depth cameras allow to obtain a complete 3D description of the framed scene while the Leap Motion sensor is a device explicitly targeted for hand gesture recognition and provides only a limited set of relevant points. This paper shows how to jointly exploit the two types of sensors for accurate gesture recognition. An ad-hoc solution for the joint calibration of the two devices is firstly presented. Then a set of novel feature descriptors is introduced both for the Leap Motion and for depth data. Various schemes based on the distances of the hand samples from the centroid, on the curvature of the hand contour and on the convex hull of the hand shape are employed and the use of Leap Motion data to aid feature extraction is also considered. The proposed feature sets are fed to two different classifiers, one based on multi-class SVMs and one exploiting Random Forests. Different feature selection algorithms have also been tested in order to reduce the complexity of the approach. Experimental results show that a very high accuracy can be obtained from the proposed method. The current implementation is also able to run in real-time
Freehand 2D Ultrasound Probe Calibration for Image Fusion with 3D MRI/CT
The aim of this work is to implement a simple freehand ultrasound (US) probe
calibration technique. This will enable us to visualize US image data during
surgical procedures using augmented reality. The performance of the system was
evaluated with different experiments using two different pose estimation
techniques. A near-millimeter accuracy can be achieved with the proposed
approach. The developed system is cost-effective, simple and rapid with low
calibration erro
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