US Army researchers have discovered a new technique for augmented reality (AR) that could help the service improve the target acquisition capability of soldiers in daylight conditions.
Researchers from the US Army Combat Capabilities Development Command, now known as DEVCOM, Army Research Laboratory have identified a way for AR to overcome bright lighting conditions during the day by using low contrast dimming highlights. They said this opens up new research questions that will improve warfighter AR and heads-up display performance in outdoor operations.
“Imagine a soldier of the future, searching for a target in an urban jungle,” said Dr. Chou Hung, a neuroscience researcher at the lab. “He looks out in the street and sees drones searching outside. He looks back down the dark hallway. The goggles instantly highlight the location of the target that the drone saw behind the wall, and the highlight is automatically adjusted to the right level in the dim environment, so that the soldier also sees a second target in another room that was missed by the drone.”
In this scenario, the highlight worked. It was at the right level of contrast to attract the soldier’s attention, but not so strong that it caused him to miss the second target that wasn’t highlighted.
“We knew that AR displays work well indoors, but outdoors, the icons disappear because the displays have limited brightness,” Hung said. “Even at the brightest level, they’re up to 100 times dimmer than a bright sunny day, so the icons and target highlights become invisible.”
Hung said it’s difficult to make the displays brighter due to the amount of power needed and it’s hard (and computationally expensive with existing technology) to make sure the highlighting isn’t so strong that it prevents the soldier from paying attention to the rest of the scene.
“We proposed a new approach, low contrast dimming, that can be used to titrate the visibility of target highlighting, but we were concerned that strong lighting variations on the retina as we shift our gaze would drown out the signal,” Hung said. “Our research shows that it should work; our visual system is actually very resilient to strong luminance dynamics; we can see very low contrast (10%) immediately after looking at something 100 times brighter.”
Researchers said future warfighters will need AR in outdoor and mixed indoor/outdoor environments.
“Our discovery paves the way towards enabling that use, including in challenging desert, snow, marine, and dense urban environments,” Hung said. “The same approach could also improve situational awareness for other display technologies such as image intensifiers, infrared and fused night vision displays. This approach would also enable indirect optics and has potential for laser eye protection as well.”
According to Col. James Ness, professor of engineering psychology at the US Military Academy, “Indirect viewing optics are definitely needed as laser powers that shift blue when hitting optics designed to filter harmful wavelengths become transparent.”
The researchers studied high dynamic range, or HDR, luminance – images in which the brightest and darkest pixels differ by up to 100,000-to-1 ratio in brightness – and how it affects visual processing.
“We believe this should increase situational awareness and intel, and avoid situations where information is lost because the display is simply invisible under bright conditions,” Hung said.
“For example, if you’re in hotel room looking outside, we see both inside and outside simultaneously, but a typical camera can only see one or the other because of limited dynamic range, and current AR technology would have the same display problem. This would ensure that the information is visible on both parts of the screen, when it’s shown against the outside and when it’s shown against the indoor environment.”
Researchers said success will also make future commercial AR more functional in daytime environments.