Perception of motion-defined form is important in operational tasks such as search and rescue and camouflage breaking. Previously, we used synthetic Aviator Night Vision Imaging System (ANVIS-9) imagery to demonstrate that the capacity to detect motion-defined form was degraded at low levels of illumination (see Macuda et al., 2004; Thomas et al., 2004). To validate our simulated NVG results, the current study evaluated observer’s ability to detect motion-defined form through a real ANVIS-9 system. The image sequences consisted of a target (square) that moved at a different speed than the background, or only depicted the moving background. For each trial, subjects were shown a pair of image sequences and required to indicate which sequence contained the target stimulus. Mean illumination and hence image noise level was varied by means of Neutral Density (ND) filters placed in front of the NVG objectives. At each noise level, we tested subjects at a series of target speeds. With both real and simulated NVG imagery, subjects had increased difficulty detecting the target with increased noise levels, at both slower and higher target speeds. These degradations in performance should be considered in operational planning. Further research is necessary to expand our understanding of the impact of NVG-produced noise on visual mechanisms.

Users of night vision goggles (NVGs) have reported differences in NVG noise across different as well as the same type of NVG. To better understand these differences, we attempted to characterize NVG noise by having subjects choose parameters in an NVG simulation to best match the noise in real NVGs. From our previous efforts, we observed interdependence of simulation parameters and variability across observers. This has lead us to use the method of paired comparisons as a process for characterizing NVG noise. The results suggest that people perceive NVG noise differently in terms of spatial, temporal, and contrast combinations. In addition, we provide a methodology for determining psychophysically the best parameter combinations in a simulation’s algorithm to match the real environment that the simulation represents.

When a bright light source is viewed through Night Vision Goggles (NVG), the image of the source can appear enveloped in a “halo” that is much larger than the “weak-signal” point spread function of the NVG. The halo phenomenon was investigated in order to produce an accurate model of NVG performance for use in psychophysical experiments. Halos were created and measured under controlled laboratory conditions using representative Generation III NVGs. To quantitatively measure halo characteristics, the NVG eyepiece was replaced by a CMOS imager. Halo size and intensity were determined from camera images as functions of point-source intensity and ambient scene illumination. Halo images were captured over a wide range of source radiances (7 orders of magnitude) and then processed with standard analysis tools to yield spot characteristics. The spot characteristics were analyzed to verify our proposed parametric model of NVG halo event formation. The model considered the potential effects of many subsystems of the NVG in the generation of halo: objective lens, photocathode, image intensifier, fluorescent screen and image guide. A description of the halo effects and the model parameters are contained in this work, along with a qualitative rationale for some of the parameter choices.

Several methodologies have been used to determine resolution acuity through Night Vision Goggles. The present study compared NVG acuity estimates derived from the Hoffman ANV-126 and a standard psychophysical grating acuity task. For the grating acuity task, observers were required to discriminate between horizontal and vertical gratings according to a method of constant stimuli. Psychometric functions were generated from the performance data, and acuity thresholds were interpolated at a performance level of 70% correct. Acuity estimates were established at three different illumination levels (0.06-5X10^-4 lux) for both procedures. These estimates were then converted to an equivalent Snellen value. The data indicate that grating acuity estimates were consistently better (i.e. lower scores) than acuity measures obtained from the Hoffman ANV-126. Furthermore significant differences in estimated acuity were observed using different tube technologies. In keeping with previous acuity investigations, although the Hoffman ANV-126 provides a rapid operational assessment of tube acuity, it is suggested that more rigorous psychophysical procedures such as the grating task described here be used to assess the real behavioural resolution of tube technologies.

Anecdotal reports by pilots flying with Night Vision Goggles (NVGs) in urban environments suggest that halos produced by bright light sources impact flight performance. The current study developed a methodology to examine the impact of viewing distance on perceived halo size. This was a first step in characterizing the subtle phenomenon of halo. Observers provided absolute size estimates of halos generated by a red LED at several viewing distances. Physical measurements of these halos were also recorded. The results indicated that the perceived halo linear size decreased as viewing distance was decreased. Further, the data showed that halos subtended a constant visual angle on the goggles (1°48’, ±7’) irrespective of distance up to 75’. This invariance with distance may impact pilot visual performance. For example, the counterintuitive apparent contraction of halo size with decreasing viewing distance may impact estimates of closure rates and of the spatial layout of light sources in the scene. Preliminary results suggest that halo is a dynamic phenomenon that requires further research to characterize the specific perceptual effects that it might have on pilot performance.

In order for night vision goggles (NVGs) to be effective in aircraft operations, it is necessary for the cockpit lighting and displays to be NVG compatible. It has been assumed that the cockpit lighting is compatible with NVGs if the radiance values are compliant with the limits listed in Mil-L-85762A and Mil-Std-3009. However, these documents also describe a NVG-lighting compatibility field test procedure that is based on visual acuity. The objective of the study described in this paper was to determine how reliable and precise the visual acuity-based (VAB) field evaluation method is and compare it to a VAB method that employs less expensive equipment. In addition, an alternative, objective method of evaluating compatibility of the cockpit lighting was investigated. An inexpensive cockpit lighting simulator was devised to investigate two different interference conditions and six different radiance levels per condition. This paper describes the results, which indicate the objective method, based on light output of the NVGs, is more precise and reliable than the visual acuity-based method. Precision and reliability were assessed based on a probability of rejection (of the lighting system) function approach that was developed specifically for this study.

Night Vision Goggles (NVGs) are being used increasingly by the military and law enforcement agencies for night operations. One critical issue in assessing the utility of an NVG is its resolving power or capability to make fine detail distinguishable. The resolution of Night Vision Goggles is typically assessed by measuring the visual acuity of an operator looking through the goggles. These methods can be time consuming. Further, inconsistencies associated with visual observations and judgement add to the variance associated with these measurements. NVG Modulation Transfer Function (MTF) was explored as a possible means of characterizing NVG image quality independent of a human observer. MTF maps the potential contrast output of the NVGs as a function of spatial frequency. The results of this MTF measurement were compared with a commonly used method of visual acuity assessment.

The Joint Helmet Mounted Cueing System (JHMCS),is being considered for integration into the F-15, F-16, and F-18 aircraft. If this integration occurs, similar monocular head-mounted displays (HMDs) will need to be integrated with existing out-the-window simulator systems for training purposes. One such system is the Mobile Modular Display for Advanced Research and Training (M2DART), which is constructed with flat-panel rear-projection screens around a nominal eye-point. Because the panels are flat, the distance from the eye point to the display screen varies depending upon the location on the screen to which the observer is directing fixation. Variation in focal distance may create visibility problems for either the HMD symbology or the out-the-window imagery presented on the simulator rear-projection display screen because observers may not be able to focus both sets of images simultaneously. The extent to which blurring occurs will depend upon the difference between the focal planes of the simulator display and HMD as well as the depth of focus of the observer. In our psychophysical study, we investigated whether significant blurring occurs as a result of such differences in focal distances and established an optimal focal distance for an HMD which would minimize blurring for a range of focal distances representative of the M2DART. Our data suggest that blurring of symbology due to differing focal planes is not a significant issue within the range of distances tested and that the optimal focal distance for an HMD is the optical midpoint between the near and far rear-projection screen distances.

As display technology moves forward, we are seeing the replacement of paper information in cockpits with digital information. Soon the stack of paper carried on the pilot’s knee will be replaced with a digital kneeboard in which the information will not only be displayed, but also manipulated and changed. There are several options for viewing this information, including both a helmet-mounted display (HMD), a small display that rests on the knee (replacing its paper counterpart) or is mounted in the airframe. However, in either case the question arises as to what are the resolution and field-of-view requirements for optimal performance of various tasks. We examined the readability and task performance using the Antelope Technologies Rugged Handheld 01 display which has a resolution of 1024 x 768 (XGA), and the ADR model FG-8000 display with a resolution of 800 x 600 (SVGA). These two displays were used to manipulate the resolution variable as they were each used only in their native mode. Usability was tested with three different tasks at varying fields-of-view (FOV). The tasks required finding and reporting information displayed from: 1) aviation approach plates, 2) FalconView mission planning software, and 3) pseudo-checklists. For the checklist tasks we also manipulated font size to more precisely investigate readability. Results are discussed in terms of both FOV and resolution requirements for each of the tasks. Several recommendations are given for both display requirements as well as tests for examining usability of digital kneeboards.

The literature describes the opt-kinetic cervical reflex (OKCR) as potentially contributing to episodes of spatial disorientation and dangerous control input reversal errors. The OKCR is described as a reflex tilting of a pilot’s head that occurs when an aircraft banks and turns under visual meteorological conditions. The implication is that with the aircraft’s banking turn, the horizon appears to the pilot to bank in the opposite directions. This banking of the horizon relative to the pilot is thought to cause the pilot’s head to tilt in order to be perpendicular to the horizon. This OKCR head tilting phenomenon may be important for the design of the head mounted display systems since these systems may be referenced to either the tilting head or the aircraft. The choice is particularly important for the display of aircraft attitude information, which is most commonly referenced to the horizon. The present paper describes an alternative explanation for the observed head tilting behavior of the pilot in a banking turn. This explanation is based on the analysis of an archived database containing the head movement records of four military pilots as they executed a slalom flight maneuver in an AH Mk 7 Lynx helicopter. These data had been collected for purposes unrelated to the present discussion, and previous analyses addressing these original purposed have already been reported. In addition to the description of the new model based on the archived database, the present paper used some results previously published in the literature to compare the new explanation and the tradition OKCR explanation of the observed head tilting behavior of pilots. A clarification of the mechanisms responsible for the observed head tilt phenomena is important for the design of the head mountedinformational display systems.

iBot is an integration of a number of fairly mature technologies - HUD, speech to text, remote pointers, integrated sensors and low power transceivers - that can be linked to the desktop computer via an RF connection giving the user the desired freedom as well as, for those users in a space constrained environment, the desktop space required for a monitor, keyboard and mouse.

Four monocular Head-Mounted Display (HMD) prototypes from the Fire Information and Rescue Equipment (FIRE) project at UC Berkeley are presented. The FIRE project aims to give firefighters a system of information technology tools for safer and more efficient firefighting in large buildings. The paper begins by describing the FIRE project and its use of a custom wireless sensor network (WSN) called SmokeNet for personnel tracking. The project aims to address urban/industrial firefighting procedures in need of improvement. Two “user-needs” studies with the Chicago and Berkeley Fire Departments are briefly presented. The FIRE project’s initial HMD prototype designs are then discussed with regard to feedback from the user-needs studies. These prototypes are evaluated in their potential costs and benefits to firefighters and found to need improvement. Next, some currently available commercial HMDs are reviewed and compared in their cost, performance, and potential for use by firefighters. Feedback from the Berkeley Fire Department user-needs study, in which the initial prototypes were demonstrated, is compiled into a concept selection matrix for the next prototypes. This matrix is used to evaluate a variety of HMDs, including some of the commercial units presented, and to select the best design options. Finally, the current prototypes of the two best design options are presented and discussed.

This system provides real-time guidance for training and problem-solving on production-line machinery. A prototype of a wearable, real-time, video guidance, interactive system for use in manufacturing, has been developed and demonstrated. Anticipated benefits are: relatively inexperienced personnel can provide machine servicing and the dependency on the vendor to repair or maintain equipment is significantly reduced. Additionally, servicing, training or part change-over schedules can be exercised more predictably and with less training. This approach utilizes Head Worn Display or Head Mounted Display (HMD) technology that can be readily adapted for various machines on the factory floor with training steps for a new location. Such a system can support various applications in manufacturing such as direct video guiding or applying scheduled maintenance and training to effectively resolve servicing emergencies and reduce machine downtime. It can also provide training of inexperienced operators and maintenance personnel. The gap between production line complexity and ability of production personnel to effectively maintain equipment is expected to widen in the future and advanced equipment will require complex servicing procedures that are neither well documented nor user-friendly. This system offers benefits in increased manufacturing equipment availability by facilitating effective servicing and training and can interface to a server system for additional computational resources on an as-needed basis. This system utilizes markers to guide the user and enforces a well defined sequence of operations. It performs augmentation of information on the display in order to provide guidance in real-time.

Helmet-mounted displays need a data feed that is typically provided by a cable or RF wireless data link to an external computer. In defense applications these solutions are problematic: a cable gets in the way and restricts use and emergency egress, while an RF wireless link can be detected at some distance giving away position and is susceptible to jamming. What is required is an alternative wireless technology that is low power, extremely localized and difficult to detect or jam. Near field magnetic communications is one possible alternative to RF communications that may fulfill these needs. This technology uses a time varying magnetic field to carry information, and is only useable over small distances of order six feet. This is expected to have significant advantages for particular applications: notably power requirements and security compared with RF wireless links. The power stored in a magnetic field falls off as 1/r6, compared with 1/r2 for RF, which means that all the power is localized around the transmitter. By having a physically small communications region around each platform or user, a large bandwidth can be guaranteed by allowing the reuse of the frequency spectrum outside the immediate vicinity. It also confers security on the data-link, as the signal is undetectable beyond the short range of the system.

Head-mounted or helmet-mounted displays (HMDs) have long proven invaluable for many military applications. Integrated with head position, orientation, and/or eye-tracking sensors, HMDs can be powerful tools for training. For such training applications as flight simulation, HMDs need to be lightweight and compact with good center-of-gravity characteristics, and must display realistic full-color imagery with eye-limited resolution and large field-of-view (FOV) so that the pilot sees a truly realistic out-the-window scene. Under bright illumination, the resolution of the eye is ~300 μr (1 arc-min), setting the minimum HMD resolution. There are several methods of achieving this resolution, including increasing the number of individual pixels on a CRT or LCD display, thereby increasing the size, weight, and complexity of the HMD; dithering the image to provide an apparent resolution increase at the cost of reduced frame rate; and tiling normal resolution subimages into a single, larger high-resolution image. Physical Optics Corporation (POC) is developing a 5120 × 4096 pixel HMD covering 1500 × 1200 mr with resolution of 300 μr by tiling 20 subimages, each of which has a resolution of 1024 × 1024 pixels, in a 5 × 4 array. We present theory and results of our preliminary development of this HMD, resulting in a 4k × 1k image tiled from 16 subimages, each with resolution 512 × 512, in an 8 × 2 array.

Active Matrix Organic Light Emitting Diode (AMOLED) displays are known to exhibit high levels of performance, and these levels of performance have continually been improved over time with new materials and electronics design. eMagin Corporation developed a manually adjustable temperature compensation circuit with brightness control to allow for excellent performance over a wide temperature range. Night Vision and Electronic Sensors Directorate (US Army) tested the performance and survivability of a number of AMOLED displays in a temperature chamber over a range from -55°C to +85°C. Although device performance of AMOLEDs has always been its strong suit, the issue of usable display lifetimes for military applications continues to be an area of discussion and research. eMagin has made improvements in OLED materials and worked towards the development of a better understanding of usable lifetime for operation in a military system. NVESD ran luminance degradation tests of AMOLED panels at 50°C and at ambient to characterize the lifetime of AMOLED devices. The result is a better understanding of the applicability of AMOLEDs in military systems: where good fits are made, and where further development is needed.

The Visually Coupled Acquisition Targeting System (VCATS) was initiated by the Air Force Research Laboratory (AFRL) and the Air Combat Command (ACC) to perform the risk reduction activities for developing a helmet-mounted tracker/display (HMT/D) in the air-to-air engagement arena. VCATS started as a one-year Operational Utility Evaluation (OUE) at Nellis Air Force Base (AFB), but expanded into a seven-year OUE, examining the human performance issues and the operational impacts of using an HMT/D for aircrews (See Figure 1). The VCATS system was designed and built with foresight and flexibility to allow upgrades more easily as technology and operational concepts evolved. This paper will trace this evolution of the VCATS system through initial design concept, system upgrades, technology transitions, and lessons learned.

As the Army increases its reliance upon and continues to develop helmet mounted displays (HMDs) or head-up displays (HUDs), it is paramount that displays are developed that meet the operational needs of the warfighter. During the development cycle, questions always arise concerning the operational requirements of the HMD. These include questions concerning luminance, contrast, color and resolution. To provide intelligent answers to these operational questions, a method has been devised to evaluate these issues. Integral to this method is an HMD simulation model that was previously presented at this meeting. The model is continually undergoing improvements with additional features and improved accuracy. The model allows for the simulation of see-through images with overlaid symbology. In this study, symbology was overlaid over eight natural images, one uniform field, and one artificial background composed of moderate to high spatial frequencies. Observers graded the quality of symbology on a scale of 1 to 7, with 7 representing symbology of high contrast and excellent quality. In all, observers graded 200 images (20 images per background scene). These images ranged from an average Michaelson contrast value of about 0.09 to 0.93. We found, as have others, that the complexity of the backgrounds greatly affected the observer’s rating. The simulated images were analyzed and statistical correlates were developed that could relate to the observer’s ratings. Metrics were developed that could help predict the luminance requirements for HMD or HUD symbology.

Military missions often require drivers to maneuver across hazardous, off-road terrain using visual displays rather than direct vision. When soldiers use 2D displays, significantly more mobility errors occur than when soldiers use 3D displays that provide a stereoscopic view of the terrain. The purposes of the present experiment were to quantify the visual forewarning of a drop-off provided by a stereoscopic 3D display compared to a 2D display, and to measure the potential of increased camera separation (i.e., hyperstereo) for enhancing the benefit of 3D for the detection of terrain drop-offs. This experiment consisted of four viewing conditions: 0X (the 2D condition), 1X (stereo with the normal interpupillary distance [IPD] between the viewpoints provided to the two eyes), 2X (stereo with twice the normal IPD), and 3X (stereo with three times the normal IPD). Thirty-two participants viewed 80 video clips, each clip depicting an approach to a terrain drop-off as would be seen in a daytime driving situation. As soon as the drop-off became apparent, he or she pressed a brake pedal. As expected, the average detection time for drop-offs viewed with 1X (stereo display) was significantly better than when drop-offs were viewed with the 0X (2D) display. The failure to observe further improvements in task performance with 2X and 3X IPD suggests follow-on research to determine whether these unexpected hyperstereo results may be attributable to adverse side effects of hyperstereo: increased mismatch between accommodation and convergence, the minification effect, and increased stereoscopic “frame violation.”

Anecdotal evidence suggested that bright, night-vision imaging system (NVIS) compatible, green cockpit displays could cause a veiling luminance in night-vision goggles (NVGs) and degrade visual performance. The mechanism suspected of causing this veiling luminance was an infrared emission from the image intensifier tube photocathode stimulated by visible, NVIS compatible light. This paper describes an effort to measure this stimulated infrared emission from three different image intensifier tubes. Measurements of the emission were analyzed with respect to tube age, the wavelength of incident illumination, and illumination angle of incidence. The emission was found during certain combinations of light wavelengths, angles, and intensities. However, results suggest that this phenomenon is not sufficiently strong to cause observable veiling luminance in NVGs.

As part of a 2003 survey during Operation Iraqi Freedom, forty AH-64 Apache aviators were interviewed regarding their experience using the AH-64’s monocular helmet-mounted display (HMD). Participants represented a total of 8564 flight hours and 2260 combat hours in the OIF theatre of operation. The interview consisted of 12 questions that addressed previously identified potential problem areas (e.g., maintaining full field-of-view [FOV], combiner breakage, and sensor slew rate) and requested participant opinion on the best and worst features of the IHADSS, day versus night use of the IHADSS, and the acceptance of a hypothetical binocular IHADSS design. Participants expressed a desire for a larger FOV; emphasized the impact of poor helmet fit on ability to achieve and maintain a full FOV; decried the overall performance of the current FLIR sensors; and reported that the current slew rates for the PNVS and TADS are slower than desired (worse for TADS), necessitating compensation in normal head movement rates.