63,363 research outputs found
Unobtrusive and pervasive video-based eye-gaze tracking
Eye-gaze tracking has long been considered a desktop technology that finds its use inside the traditional office setting, where the operating conditions may be controlled. Nonetheless, recent advancements in mobile technology and a growing interest in capturing natural human behaviour have motivated an emerging interest in tracking eye movements within unconstrained real-life conditions, referred to as pervasive eye-gaze tracking. This critical review focuses on emerging passive and unobtrusive video-based eye-gaze tracking methods in recent literature, with the aim to identify different research avenues that are being followed in response to the challenges of pervasive eye-gaze tracking. Different eye-gaze tracking approaches are discussed in order to bring out their strengths and weaknesses, and to identify any limitations, within the context of pervasive eye-gaze tracking, that have yet to be considered by the computer vision community.peer-reviewe
Adaptive User Perspective Rendering for Handheld Augmented Reality
Handheld Augmented Reality commonly implements some variant of magic lens
rendering, which turns only a fraction of the user's real environment into AR
while the rest of the environment remains unaffected. Since handheld AR devices
are commonly equipped with video see-through capabilities, AR magic lens
applications often suffer from spatial distortions, because the AR environment
is presented from the perspective of the camera of the mobile device. Recent
approaches counteract this distortion based on estimations of the user's head
position, rendering the scene from the user's perspective. To this end,
approaches usually apply face-tracking algorithms on the front camera of the
mobile device. However, this demands high computational resources and therefore
commonly affects the performance of the application beyond the already high
computational load of AR applications. In this paper, we present a method to
reduce the computational demands for user perspective rendering by applying
lightweight optical flow tracking and an estimation of the user's motion before
head tracking is started. We demonstrate the suitability of our approach for
computationally limited mobile devices and we compare it to device perspective
rendering, to head tracked user perspective rendering, as well as to fixed
point of view user perspective rendering
Systematics of electronic and magnetic properties in the transition metal doped SbTe quantum anomalous Hall platform
The quantum anomalous Hall effect (QAHE) has recently been reported to emerge
in magnetically-doped topological insulators. Although its general
phenomenology is well established, the microscopic origin is far from being
properly understood and controlled. Here we report on a detailed and systematic
investigation of transition-metal (TM)-doped SbTe. By combining density
functional theory (DFT) calculations with complementary experimental
techniques, i.e., scanning tunneling microscopy (STM), resonant photoemission
(resPES), and x-ray magnetic circular dichroism (XMCD), we provide a complete
spectroscopic characterization of both electronic and magnetic properties. Our
results reveal that the TM dopants not only affect the magnetic state of the
host material, but also significantly alter the electronic structure by
generating impurity-derived energy bands. Our findings demonstrate the
existence of a delicate interplay between electronic and magnetic properties in
TM-doped TIs. In particular, we find that the fate of the topological surface
states critically depends on the specific character of the TM impurity: while
V- and Fe-doped SbTe display resonant impurity states in the vicinity
of the Dirac point, Cr and Mn impurities leave the energy gap unaffected. The
single-ion magnetic anisotropy energy and easy axis, which control the magnetic
gap opening and its stability, are also found to be strongly TM
impurity-dependent and can vary from in-plane to out-of-plane depending on the
impurity and its distance from the surface. Overall, our results provide
general guidelines for the realization of a robust QAHE in TM-doped
SbTe in the ferromagnetic state.Comment: 40 pages, 13 figure
A multi-projector CAVE system with commodity hardware and gesture-based interaction
Spatially-immersive systems such as CAVEs provide users with surrounding worlds by projecting 3D models on multiple screens around the viewer. Compared to alternative immersive systems such as HMDs, CAVE systems are a powerful tool for collaborative inspection of virtual environments due to better use of peripheral vision, less sensitivity to tracking errors, and higher communication possibilities among users. Unfortunately, traditional CAVE setups require sophisticated equipment including stereo-ready projectors and tracking systems with high acquisition and maintenance costs. In this paper we present the design and construction of a passive-stereo, four-wall CAVE system based on commodity hardware. Our system works with any mix of a wide range of projector models that can be replaced independently at any time, and achieves high resolution and brightness at a minimum cost. The key ingredients of our CAVE are a self-calibration approach that guarantees continuity across the screen, as well as a gesture-based interaction approach based on a clever
combination of skeletal data from multiple Kinect sensors.Preprin
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