“The technology has progressed a lot in terms of visual systems, and that’s why we’re here today,” says St-Hilaire. He recalls seeing Unreal Engine entering the simulation arena 10 years ago.“Back then, we were seeing part-task trainers or lower-level task trainers developed with game engines, first-person shooter and tactical training,” he says. “It was very disruptive because you had a turnkey system in a single package—you had the development environment as the tool and the means to distribute your own solution.” He adds that Unreal Engine’s ecosystem of content and community was also disruptive to the simulation industry.
Since then, St-Hilaire notes, game engine technology has advanced, along with GPU power and other elements that comprise a simulation solution, to solve many of the challenges the simulation industry was dealing with in creating a convincing, effective training solution: global coordinates that resolve correctly over long distances, low latency, and of course, graphics quality, just to name a few.
Solving latency in simulation
St-Hilaire illustrates the importance of low simulator latency by comparing a flight simulator to a closed control loop, where the trainee applies force to the yoke and experiences a number of sensations. “Pilots sense motion through their bodies. Their eyes are telling them where they are and where they’re going; their inner ears are sensing acceleration and rotation; their sense of touch provides force feedback. That loop is very delicate,” St-Hilaire explains. “Any latency, any delay in that loop, will make something feel incorrect, can impact the pilot’s control of the simulated aircraft, and overall will make the pilot disconnect from the experience.”
Latency is so critical, St-Hilaire says, that industry regulators prescribe an upper limit of 90 milliseconds for all delays and latency, starting from when the pilot moves a control, through the display of visuals, along with any other data transfers and calculations that take place.
“If I’m training on a fighter simulator in a joint scenario, my wingman on the other simulator has to see what I’m seeing,” St-Hilaire says. “If I shoot down something, both of us need to see at the same time that I shot it down.”
This, he says, highlights the importance of network latency—it’s just as critical as the simulator’s own latency in keeping the simulation immersive, realistic, and effective for training.
Moving toward standardization
About 15 years ago, CAE moved its development focus to make use of commercial GPUs and drivers, and has been riding that journey of pilot visual calculations ever since. This, St-Hilaire points out, is another example of technology changes in the process of creating the visuals themselves.
Source: Unreal Engine Blog