Head-mounted display | EPFL Graph Search

A head-mounted display (HMD) is a display device, worn on the head or as part of a helmet (see Helmet-mounted display for aviation applications), that has a small display optic in front of one (monocular HMD) or each eye (binocular HMD). An HMD has many uses including gaming, aviation, engineering, and medicine. Virtual reality headsets are HMDs combined with IMUs. There is also an optical head-mounted display (OHMD), which is a wearable display that can reflect projected images and allows a user to see through it. A typical HMD has one or two small displays, with lenses and semi-transparent mirrors embedded in eyeglasses (also termed data glasses), a visor, or a helmet. The display units are miniaturized and may include cathode ray tubes (CRT), liquid-crystal displays (LCDs), liquid crystal on silicon (LCos), or organic light-emitting diodes (OLED). Some vendors employ multiple micro-displays to increase total resolution and field of view. HMDs differ in whether they can display only (CGI), or only live imagery from the physical world, or combination. Most HMDs can display only a computer-generated image, sometimes referred to as virtual image. Some HMDs can allow a CGI to be superimposed on real-world view. This is sometimes referred to as augmented reality (AR) or mixed reality (MR). Combining real-world view with CGI can be done by projecting the CGI through a partially reflective mirror and viewing the real world directly. This method is often called optical see-through. Combining real-world view with CGI can also be done electronically by accepting video from a camera and mixing it electronically with CGI. Optical head-mounted displayAn optical head-mounted display uses an optical mixer which is made of partly silvered mirrors. It can reflect artificial images, and let real images cross the lens, and let a user look through it. Various methods have existed for see-through HMD's, most of which can be summarized into two main families based on curved mirrors or waveguides.

On the Importance of Providing a Tangible Haptic Response for Training Cardiopulmonary Resuscitation in Virtual Reality

Ronan Boulic, Bruno Herbelin, Mathias Guy Delahaye

The current approach to train Cardiopulmonary Resuscitation (CPR) is to employ a mannequin device replicating the physical properties of a real human head and torso. This aims to ensure a correct transfer of the cardiac massage location, amplitude and frequency in a real situation. However, this type of training does not replicate the stress that may be elicited in the presence of a real victim ; this may result in reduced CPR performances or even errors. Virtual Reality (VR) may alleviate this lack by adding visual immersion with a Head-Mounted Display (HMD) so that the trainee is cut from the potential distractions of the real surrounding and can fully engage in a more faithful training scenario. However, one must ensure in the first place that using this technology maintains the quality of the CPR. Hence, we have conducted an experimental study to evaluate the potential of visual immersion in such a training context (limited to the cardiac massage). One important requirement was to ensure a correct hand tracking while executing the standard CPR two-hands pose. In the present paper we describe first how we assessed a simple approach using two HTC-Vive trackers. Results show that the proposed minimal setup based on a single hand tracking is validated for frequency and, with correction, for amplitude. Then, to assess the quality of the training, we performed an evaluation study considering the following two factors: Haptic feedback with the mannequin device (with/out) and Real-time Performance feedback (with/out) in the HMD. We observed that the visually immersive experience proposed in this paper delivers a sufficient level of spatial presence, involvement and agency. Integrating the real CPR mannequin in VR has a significantly positive impact on the massage performance quality whereas displaying the real-time performance in the virtual environment tends to be only useful for the frequency when no mannequin is used.

The Eurographics Association2021

An Authoring Model For Interactive 360 Videos

Roberto Gerson De Albuquerque Azevedo

The recent availability of consumer-level head-mounted displays and omnidirectional cameras has been driving an explosion of 360 video content. Transforming the original recorded 360 video content in meaningful interactive multimedia presentations that support viewers in tasks such as learning, entertainment, and telepresence, however, is not trivial and requires new tools. Such tools must provide an easy-to-use authoring model for the integration of different media objects and active user interface elements.In this paper, based on real-world scenarios for interactive 360 videos, we gather a set of requirements and propose a declarative authoring model to support authors in the process of designing and creating 360-degree interactive video presentations. As a case study, we implement different applications showing the expressiveness and completeness of the model in the scope of the target scenarios.

IEEE2020

Subjective and Viewport-based Objective Quality Assessment of 360-degree Videos

Pascal Frossard, Roberto Gerson De Albuquerque Azevedo

Visual distortions in processed 360-degree visual content and consumed through head-mounted displays (HMDs) are perceived very differently when compared to traditional 2D content. To better understand how compression-related artifacts affect the overall perceived quality of 360-degree videos, this paper presents a subjective quality assessment study and analyzes the performance of objective metrics to correlate with the gathered subjective scores. In contrast to previous related work, the pro- posed study focuses on the equiangular cubemap projection and includes specific visual distortions (blur, blockiness, H.264 compression, and cubemap seams) on both monoscopic and stereoscopic sequences. The objective metrics performance analysis is based on metrics computed in both the projection domain and the viewports, which is closer to what the user sees. The results show that overall objective metrics computed on viewports are more correlated with the subjective scores in our dataset than the same metrics computed in the projection domain. Moreover, the proposed dataset and objective metrics analysis serve as a bench- mark for the development of new perception-optimized quality assessment algorithms for 360-degree videos, which is still a largely open research problem.

2020

On the Importance of Providing a Tangible Haptic Response for Training Cardiopulmonary Resuscitation in Virtual Reality

Ronan Boulic, Bruno Herbelin, Mathias Guy Delahaye

The Eurographics Association2021