1,721,039 research outputs found
The role of camera convergence in stereoscopic video see-through augmented reality displays
Full text linkIn the realm of wearable augmented reality (AR) systems, stereoscopic video see-through displays raise issues related to the user's perception of the three-dimensional space. This paper seeks to put forward few considerations regarding the perceptual artefacts common to standard stereoscopic video see-through displays with fixed camera convergence. Among the possible perceptual artefacts, the most significant one relates to diplopia arising from reduced stereo overlaps and too large screen disparities. Two state-of-the-art solutions are reviewed. The first one suggests a dynamic change, via software, of the virtual camera convergence, whereas the second one suggests a matched hardware/software solution based on a series of predefined focus/vergence configurations. Potentialities and limits of both the solutions are outlined so as to provide the AR community, a yardstick for developing new stereoscopic video see-through systems suitable for different working distances
Procedimento e sistema per Ia rappresentazione tridimensionale di una scena a realta aumentata, particolarmente per applicazioni chirurgiche"
No full textAbstract not availabl
An Occlusion-Robust Optical-Inertial Tracking Solution for Augmented Reality Headsets
No full textAugmented Reality (AR) is a technology that is
increasingly used to guide manual tasks and aid the user in
enabling vision that would not be possible with the naked eye.
For example, in the surgical field, this aid consists of
visualising occluded anatomical areas or other additional
information along the direction of view. The present work
aims to develop a sensor fusion algorithm for an AR system
based on hybrid optical-inertial tracking incorporating head
kinematics. The developed technology ensures accurate and
robust tracking, which can cope with partial and total
occlusions of optical markers by implementing a method that
integrates data from video cameras with data from a
Magnetic-Inertial Measurement Unit (MIMU) sensor
Augmented reality-guided neurosurgery
No full textLetter to the Editor: Augmented reality-guided neurosurger
Parallax Free Registration for Augmented Reality OpticalSee-through Displays in the Peripersonal Space
Full text linkEgocentric augmented reality (AR) interfaces are quickly becoming a key asset for assisting high precision activities in the peripersonal space in several application fields. In these applications, accurate and robust registration of computer-generated information to the real scene is hard to achieve with traditional Optical See-Through (OST) displays given that it relies on the accurate calibration of the combined eye-display projection model. The calibration is required to efficiently estimate the projection parameters of the pinhole model that encapsulate the optical features of the display and whose values vary according to the position of the user's eye. In this article, we describe an approach that prevents any parallax-related AR misregistration at a pre-defined working distance in OST displays with infinity focus; our strategy relies on the use of a magnifier placed in front of the OST display, and features a proper parameterization of the virtual rendering camera achieved through a dedicated calibration procedure that accounts for the contribution of the magnifier. We model the registration error due to the viewpoint parallax outside the ideal working distance. Finally, we validate our strategy on a OST display, and we show that sub-millimetric registration accuracy can be achieved for working distances of com.elsevier.xml.xocs.dtd.Math@1d6be07f mm around the focal length of the magnifier
The Right Mix of Visual and Mechanical Constraints to Guide the Relative Pose between Rigid Objects
No full textRestoring and/or obtaining the correct relative pose between rigid objects is a common precision task in many sectors, from industry to healthcare, as during the reduction of long-bones fractured. Augmented Reality (AR) can provide useful indications, showing how one bone should be positioned with respect to another, for example. However, moving a rigid body by manually managing its six degrees of freedom (DOF) until the desired pose is obtained can be difficult. At first, because AR visualization is commonly not able to provide an accurate depth perception. Second, because it is very challenging to control and handle all the six DOFs simultaneously. In this work, we evaluated whether the addition of adaptable and easily adjustable mechanical constraints, each constraining a single degree of freedom, allow increasing the feasibility, accuracy, and efficiency of an AR guidance. This preliminary study shows that handling simultaneously all the 6 DOFs of a rigid object is hardly feasible under hand-free AR guidance, and that we can therefore insert simple mechanical constraints to facilitate the achievement of the desired relative pose between rigid objects
Closed - Loop Calibration for Optical See-Through near Eye Display with Infinity Focus
No full textIn wearable augmented reality systems, optical see-through near-eye displays (OST NEDs) based on waveguides are becoming a standard as they are generally preferred over solutions based on semi-reflective curved mirrors. This is mostly due to their ability to ensure reduced image distortion and sufficiently wide eye motion box without the need for bulky optical and electronics components to be placed in front of the user's face and/or onto the user's line of sight. In OST head-mounted displays (HMDs) the user's own view is augmented by optically combining it with the virtual content rendered on a two-dimensional (2D) microdisplay. For achieving a perfect combination of the light field in the real 3D world and the computer-generated 2D graphics projected on the display, an accurate alignment between real and virtual content must be yielded at the level of the NED imaging plane. To this end, we must know the exact position of the user's eyes within the HMD reference system. State-of-the-art methods models the eye-NED system as an off-axis pinhole camera model, and therefore include the contribution of the eyes' positions into the modelling of the intrinsic matrix of the eye-NED. In this paper, we will describe a method for robustly calibrating OST NEDs that explicitly ignore this assumption. To verify the accuracy of our method, we conducted a set of experiments in a setup comprising a commercial waveguide-based OST NED and a camera in place of the user's eye. We tested a set of different camera (or eye) positions within the eye box of the NED. The obtained results demonstrate that the proposed method yields accurate results in terms of real-to-virtual alignment, regardless of the position of the eyes within the eye box of the NEDs (Figure 1). The achieved viewing accuracy was of .85 pm 1.37$ pixels
Corrigendum: Optical See-Through Head-Mounted Displays With Short Focal Distance: Conditions for Mitigating Parallax-Related Registration Error
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