Night vision

About: Night vision is a research topic. Over the lifetime, 6004 publications have been published within this topic receiving 67372 citations.

Optical waveguide technology and its application in head-mounted displays

Abstract: Applying optical waveguide technology to head mounted display (HMD) solutions has the key goal of providing the user with improved tactical situational awareness by providing information and imagery in an easy to use form which also maintains compatibility with current night vision devices and also enables the integration of future night vision devices. The benefits of waveguide technology in HMDs have seen a number of alternative waveguide display technologies and configurations emerge for Head mounted Display applications. BAE System's presented one such technology in 2009 [1] and this is now in production for a range of Helmet Mounted Display products. This paper outlines the key design drivers for aviators Helmet Mounted Displays, provides an update of holographic Optical Waveguide Technology and its maturation into compact, lightweight Helmet Mounted Displays products for aviation and non-aviation applications. Waveguide displays have proved too be a radical enabling technology which allows higher performance display devices solutions to be created in a revolutionary way. It has also provided the user with see through daylight readable displays, offering the combination of very large eye box and excellent real world transmission in a compact format. Holographic Optical Waveguide is an optical technology which reduces size and mass whilst liberating the designer from many of the constraints inherent in conventional optical solutions. This technology is basically a way of moving light without the need for a complex arrangement of conventional lenses. BAE Systems has exploited this technology in the Q-SightTM family of scalable Helmet Mounted Displays; allowing the addition of capability as it is required in a flexible, low-cost way The basic monocular Q-SightTM architecture has been extended to offer wide field of view, monochrome and full colour HMD solution for rotary wing, fast jet and solider system applications. In its basic form Q-SightTM now offers plug-and-play solutions into any cockpit with either Analogue (stroke) or Digital Video Interface (DVI) connections. This offers a significant upgrade opportunity to those users currently struggling with cumbersome legacy CRT using conventional glass optical lenses.

Even moderate visual impairments degrade drivers' ability to see pedestrians at night

Abstract: Purpose: To determine the effect of moderate levels of refractive blur and simulated cataracts on nighttime pedestrian conspicuity in the presence and absence of headlamp glare. Methods: The ability to recognize pedestrians at night was measured in 28 young adults (M=27.6 years) under three visual conditions: normal vision, refractive blur and simulated cataracts; mean acuity was 20/40 or better in all conditions. Pedestrian recognition distances were recorded while participants drove an instrumented vehicle along a closed road course at night. Pedestrians wore one of three clothing conditions and oncoming headlamps were present for 16 participants and absent for 12 participants. Results: Simulated visual impairment and glare significantly reduced the frequency with which drivers recognized pedestrians and the distance at which the drivers first recognized them. Simulated cataracts were significantly more disruptive than blur even though photopic visual acuity levels were matched. With normal vision, drivers responded to pedestrians at 3.6x and 5.5x longer distances on average than for the blur or cataract conditions, respectively. Even in the presence of visual impairment and glare, pedestrians were recognized more often and at longer distances when they wore a "biological motion" reflective clothing configuration than when they wore a reflective vest or black clothing. Conclusions: Drivers' ability to recognize pedestrians at night is degraded by common visual impairments even when the drivers' mean visual acuity meets licensing requirements. To maximize drivers' ability to see pedestrians, drivers should wear their optimum optical correction, and cataract surgery should be performed early enough to avoid potentially dangerous reductions in visual performance. Language: en

Perceptual effects in real-time tone mapping

Abstract: Tremendous progress in the development and accessibility of high dynamic range (HDR) technology that has happened just recently results in fast proliferation of HDR synthetic image sequences and captured HDR video. When properly processed, such HDR data can lead to very convincing and realistic results even when presented on traditional low dynamic range (LDR) display devices. This requires real-time local contrast compression (tone mapping) with simultaneous modeling of important in HDR image perception effects such as visual acuity, glare, day and night vision. We propose a unified model to include all those effects into a common computational framework, which enables an efficient implementation on currently available graphics hardware. We develop a post processing module which can be added as the final stage of any real-time rendering system, game engine, or digital video player, which enhances the realism and believability of displayed image streams.

Individual beacon identification system

Abstract: A compact beacon-detector type IFF system to be carried by individual soldiers. The system consists of a beacon and a special purpose detector. The beacon is a small, light-weight, battery powered device that is worn on the soldier's web gear. The detector consists of a small flashlight-like device that can be hand held or mounted on a weapon, similar to a rifle scope. The beacon's signal is not visible to those using existing night vision equipment nor is it otherwise exploitable by a potential adversary. The system achieves its covertness through the selection of the optical wavelength used by the beacon. Further signature reduction is achieved through the use of a Low Probability of Intercept ("LPI") spread spectrum waveform as the beacon output. This waveform utilizes a spreading code to encode the beacon output signal. Even if an enemy has a sensor capable of detecting the proper optical wavelength, it would not be able to detect or emulate the beacon's signal without prior knowledge of the specific spreading code used. The detector of the present invention is designed to despread the beacon output waveform, allowing the signal to be detected. This spread/despread code can be changed as frequently as required, so that capture of the beacon or detector would not be a serious risk to compromising the system.

Thresholding Using Relaxation

Abstract: If a picture contains dark objects on a light background (or vice versa), the objects can be extracted by thresholding, i.e., by classifying the pixels into ``light'' and ``dark'' classes. If the picture is noisy, so that the object and background gray level populations overlap, there will be errors in the thresholded output. A relaxation process can be used to reduce these errors; we classify the pixels probabilistically, and then adjust the probabilities for each pixel, based on its neighbors' probabilities, with light reinforcing light and dark dark. When this adjustment process is iterated, the dark probabilities become very high for pixels that belong to dark regions, and vice versa, so that thresholding becomes trivial.