scholarly journals Transverse Chromatic Aberrations in Virtual Reality Devices

Frameless ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 1-4
Author(s):  
Ryan Beams ◽  
◽  
Wei-Chung Cheng ◽  
Andrea S. Kim ◽  
Aldo Badano ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Image Quality ◽  
Relative Size ◽  
Chromatic Aberration ◽  
Field Of View ◽  
Test Results ◽  
Optical Performance ◽  
Color Changes ◽  
Head Mounted Display ◽  
Chromatic Aberrations

We demonstrate a method for measuring the transverse chromatic aberration (TCA) in a virtual reality head-mounted display (VR HMD). This procedure was used to characterize the optical performance of the Oculus Go VR HMD. Results show a measurable TCA for angles larger than approximately 6◦ from the center of the field of view. TCA can be thought of as a wavelength dependent magnification, and as a result, the relative size of objects vary based on the rendering color. In addition, this leads to color changes in the image due to mixing with neighboring pixels, which impacts image quality. The test results for the Oculus Go show promise for characterizing TCA across different HMDs.

Virtual Reality Head-Mounted Display with Large Field of View Based on Stitching

2019 ◽  
Vol 39 (6) ◽  
pp. 0612002 ◽  
Author(s):  
陆驰豪 Chihao Lu ◽  
李海峰 Haifeng Li ◽  
高涛 Tao Gao ◽  
徐良 Liang Xu ◽  
李海丽 Haili Li
Keyword(s):  
Virtual Reality ◽  
Field Of View ◽  
Large Field ◽  
Head Mounted Display

scholarly journals Colour Calibration of a Head Mounted Display for Colour Vision Research Using Virtual Reality

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Raquel Gil Rodríguez ◽  
Florian Bayer ◽  
Matteo Toscani ◽  
Dar’ya Guarnera ◽  
Giuseppe Claudio Guarnera ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Real World ◽  
Vision Research ◽  
Colour Vision ◽  
Software Implementation ◽  
Field Of View ◽  
Large Field ◽  
Colour Constancy ◽  
Head Mounted Display ◽  
Colour Appearance

AbstractVirtual reality (VR) technology offers vision researchers the opportunity to conduct immersive studies in simulated real-world scenes. However, an accurate colour calibration of the VR head mounted display (HMD), both in terms of luminance and chromaticity, is required to precisely control the presented stimuli. Such a calibration presents significant new challenges, for example, due to the large field of view of the HMD, or the software implementation used for scene rendering, which might alter the colour appearance of objects. Here, we propose a framework for calibrating an HMD using an imaging colorimeter, the I29 (Radiant Vision Systems, Redmond, WA, USA). We examine two scenarios, both with and without using a rendering software for visualisation. In addition, we present a colour constancy experiment design for VR through a gaming engine software, Unreal Engine 4. The colours of the objects of study are chosen according to the previously defined calibration. Results show a high-colour constancy performance among participants, in agreement with recent studies performed on real-world scenarios. Our studies show that our methodology allows us to control and measure the colours presented in the HMD, effectively enabling the use of VR technology for colour vision research.

scholarly journals Effects of system- and media-driven immersive capabilities on presence and affective experience

2021 ◽  
Author(s):  
Bradley Standen ◽  
John Anderson ◽  
Alexander Sumich ◽  
Nadja Heym
Keyword(s):  
Virtual Reality ◽  
Image Quality ◽  
Virtual Environment ◽  
Affective Response ◽  
Field Of View ◽  
Alpha Power ◽  
Motivational Systems ◽  
Sense Of Presence ◽  
Motivational Salience ◽  
Different Levels

AbstractVirtual reality (VR) is receiving widespread attention as a delivery tool for exposure therapies. The advantage offered by VR over traditional technology is a greater sense of presence and immersion, which magnifies user effects and enhances the effectiveness of exposure-based interventions. The current study systematically examined the basic factors involved in generating presence in VR as compared to standard technology, namely (1) system-driven factors that are exclusive to VR devices while controlling general factors such as field of view and image quality; (2) media-driven factors of the virtual environment eliciting motivational salience through different levels of arousal and valence (relaxing, exciting and fear evoking stimuli); and (3) the effects of presence on magnifying affective response. Participants (N = 14) watched 3 different emotionally salient videos (1 × fear evoking, 1 × relaxing and 1 × exciting) in both viewing modes (VR and Projector). Subjective scores of user experience were collected as well as objective EEG markers of presence (frontal alpha power, theta/beta ratio). Subjective and objective presence was significantly greater in the VR condition. There was no difference in subjective or objective presence for stimulus type, suggesting presence is not moderated by arousal, but may be reliant on activation of motivational systems. Finally, presence did not magnify feelings of relaxation or excitement, but did significantly magnify users’ experience of fear when viewing fear evoking stimuli. This is in line with previous literature showing strong links between presence and generation of fear, which is vital in the efficacy of exposure therapies.

scholarly journals Image quality guided smart rotation improves coverage in microscopy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiaye He ◽  
Jan Huisken
Keyword(s):  
Image Quality ◽  
Light Sheet ◽  
Field Of View ◽  
Optical Performance ◽  
Sample Rotation ◽  
Optical Instruments ◽  
Selective Plane Illumination Microscopy ◽  
Data Volume ◽  
Optical Paths ◽  
Additional Hardware

AbstractFluorescence microscopy is an essential tool for biological discoveries. There is a constant demand for better spatial resolution across a larger field of view. Although strides have been made to improve the theoretical resolution and speed of the optical instruments, in mesoscopic samples, image quality is still largely limited by the optical properties of the sample. In Selective Plane Illumination Microscopy (SPIM), the achievable optical performance is hampered by optical degradations encountered in both the illumination and detection. Multi-view imaging, either through sample rotation or additional optical paths, is a popular strategy to improve sample coverage. In this work, we introduce a smart rotation workflow that utilizes on-the-fly image analysis to identify the optimal light sheet imaging orientations. The smart rotation workflow outperforms the conventional approach without additional hardware and achieves a better sample coverage using the same number of angles or less and thereby reduces data volume and phototoxicity.

The Shared View Paradigm in Asymmetric Virtual Reality Setups

i-com ◽  
2020 ◽  
Vol 19 (2) ◽  
pp. 87-101
Author(s):  
Robin Horst ◽  
Fabio Klonowski ◽  
Linda Rau ◽  
Ralf Dörner
Keyword(s):  
Virtual Reality ◽  
Virtual Environments ◽  
Real World ◽  
User Study ◽  
Field Of View ◽  
Virtual Scene ◽  
Head Mounted Display ◽  
Safety Aspects ◽  
Common Technique ◽  
Visualization Techniques

AbstractAsymmetric Virtual Reality (VR) applications are a substantial subclass of multi-user VR that offers not all participants the same interaction possibilities with the virtual scene. While one user might be immersed using a VR head-mounted display (HMD), another user might experience the VR through a common desktop PC. In an educational scenario, for example, learners can use immersive VR technology to inform themselves at different exhibits within a virtual scene. Educators can use a desktop PC setup for following and guiding learners through virtual exhibits and still being able to pay attention to safety aspects in the real world (e. g., avoid learners bumping against a wall). In such scenarios, educators must ensure that learners have explored the entire scene and have been informed about all virtual exhibits in it. According visualization techniques can support educators and facilitate conducting such VR-enhanced lessons. One common technique is to render the view of the learners on the 2D screen available to the educators. We refer to this solution as the shared view paradigm. However, this straightforward visualization involves challenges. For example, educators have no control over the scene and the collaboration of the learning scenario can be tedious. In this paper, we differentiate between two classes of visualizations that can help educators in asymmetric VR setups. First, we investigate five techniques that visualize the view direction or field of view of users (view visualizations) within virtual environments. Second, we propose three techniques that can support educators to understand what parts of the scene learners already have explored (exploration visualization). In a user study, we show that our participants preferred a volume-based rendering and a view-in-view overlay solution for view visualizations. Furthermore, we show that our participants tended to use combinations of different view visualizations.

Is Virtual Reality Streaming Ready for Remote Medical Education? Measuring Latency of Stereoscopic VR for Telementoring

2021 ◽  
Vol 65 (1) ◽  
pp. 757-761
Author(s):  
Kerem C. Celebi ◽  
Shannon K. T. Bailey ◽  
Micheal W. Burns ◽  
Kunal Bansal
Keyword(s):  
Virtual Reality ◽  
Technical Skills ◽  
Field Of View ◽  
Low Latency ◽  
Healthcare Education ◽  
Test Results ◽  
Medical Specialist ◽  
Stereoscopic Video ◽  
Video And Audio ◽  
The One

Telementoring in healthcare education has been used successfully to teach technical skills and clinical reasoning when in-person instruction is not feasible; however, previous technology for telementoring had limitations such as narrow field-of-view and high latency. Novel virtual reality (VR) livestreaming technology may address issues in traditional 2-dimensional (2D) systems by expanding the field of view while streaming with low latency. Low latency streaming of video and audio is necessary for smooth communication between a medical specialist and remote trainees. If latency is low between the instructor and the remote trainees, conversations can be held without a noticeable delay, supporting synchronous instruction and collaboration. This research reports the first latency test results of a novel VR system that livestreams stereoscopic video and audio to remote VR headsets. Results showed the one-way audio and video latency was less than half a second, confirming the viability of live VR for medical telementoring.

Observability of Very Thick Specimen by Using Transmission Scanning Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 26-27
Author(s):  
K. Shibatomi ◽  
T. Yamanoto ◽  
H. Koike
Keyword(s):  
Electron Microscope ◽  
Image Quality ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Image Contrast ◽  
Objective Lens ◽  
Thick Specimen ◽  
Transmission Electron ◽  
Scanning Electron

In the observation of a thick specimen by means of a transmission electron microscope, the intensity of electrons passing through the objective lens aperture is greatly reduced. So that the image is almost invisible. In addition to this fact, it have been reported that a chromatic aberration causes the deterioration of the image contrast rather than that of the resolution. The scanning electron microscope is, however, capable of electrically amplifying the signal of the decreasing intensity, and also free from a chromatic aberration so that the deterioration of the image contrast due to the aberration can be prevented. The electrical improvement of the image quality can be carried out by using the fascionating features of the SEM, that is, the amplification of a weak in-put signal forming the image and the descriminating action of the heigh level signal of the background. This paper reports some of the experimental results about the thickness dependence of the observability and quality of the image in the case of the transmission SEM.

The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

1971 ◽  
Vol 29 ◽  
pp. 14-15
Author(s):  
J. S. Lally ◽  
R. Evans
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Usual Practice ◽  
Voltage Electron ◽  
Short Focal Length ◽  
Chromatic Aberrations ◽  
Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

Toward The Simultaneous Correction of Spherical and Chromatic Aberration in Electron Optics by Means of an Electrostatic Electron Mirror

1990 ◽  
Vol 48 (1) ◽  
pp. 206-207
Author(s):  
Gertrude. F. Rempfer
Keyword(s):  
Chromatic Aberration ◽  
Transverse Magnetic ◽  
Objective Lens ◽  
Ion Imaging ◽  
Corrected Image ◽  
Electric And Magnetic Fields ◽  
Chromatic Aberrations ◽  
Improved Performance ◽  
Electron Microscopes ◽  
Image Planes

Optimum performance in electron and ion imaging instruments, such as electron microscopes and probe-forming instruments, in most cases depends on a compromise either between imaging errors due to spherical and chromatic aberrations and the diffraction error or between the imaging errors and the current in the image. These compromises result in the use of very small angular apertures. Reducing the spherical and chromatic aberration coefficients would permit the use of larger apertures with resulting improved performance, granted that other problems such as incorrect operation of the instrument or spurious disturbances do not interfere. One approach to correcting aberrations which has been investigated extensively is through the use of multipole electric and magnetic fields. Another approach involves the use of foil windows. However, a practical system for correcting spherical and chromatic aberration is not yet available.Our approach to correction of spherical and chromatic aberration makes use of an electrostatic electron mirror. Early studies of the properties of electron mirrors were done by Recknagel. More recently my colleagues and I have studied the properties of the hyperbolic electron mirror as a function of the ratio of accelerating voltage to mirror voltage. The spherical and chromatic aberration coefficients of the mirror are of opposite sign (overcorrected) from those of electron lenses (undercorrected). This important property invites one to find a way to incorporate a correcting mirror in an electron microscope. Unfortunately, the parts of the beam heading toward and away from the mirror must be separated. A transverse magnetic field can separate the beams, but in general the deflection aberrations degrade the image. The key to avoiding the detrimental effects of deflection aberrations is to have deflections take place at image planes. Our separating system is shown in Fig. 1. Deflections take place at the separating magnet and also at two additional magnetic deflectors. The uncorrected magnified image formed by the objective lens is focused in the first deflector, and relay lenses transfer the image to the separating magnet. The interface lens and the hyperbolic mirror acting in zoom fashion return the corrected image to the separating magnet, and the second set of relay lenses transfers the image to the final deflector, where the beam is deflected onto the projection axis.

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