Sharpening Their Focus
New projector and screen technologies allow
warfighters to train with new levels of detail.
by Tom Marlowe
MT2 Correspondent
The U.S. military relies upon projectors to create simulations for training in stressful scenarios with a high op tempo. To successfully simulate battle space, the projectors must be capable of rendering highly detailed, accurate images that move by the warfighter very quickly.
As researchers at the U.S. Air Force Research Laboratory (AFRL) can attest, these requirements are a tall order for any projector, much less commercial projectors that are not built to handle anything nearly so complex. However, advances in digital technology have begun to offer warfighters the opportunity to train with a level of detail that they previously only would have found in the real world.
Dr. Byron Pierce, principal scientist of the Immersive Environments Branch at the AFRL Warfighter Readiness Research Division, spends his time studying visual, audio and tactical technologies that transport trainees into a virtual battlefield, providing them with opportunities to fly various airframes in simulated hostile environments and thereby improving their skills.
Pierce recently exchanged information with the U.S. Navy and confirmed that naval aviators have many of the same requirements for their F-18 simulators that the Air Force has for its simulation projectors: more pixels, more color and less blurring.
Higher resolution must come not simply in the sheer number of pixels on the screen but also in a high percentage of resolvable pixels, Pierce told MT2. Old CRT projectors could not necessarily present a high number of resolvable pixels.
“If you have a vertical line of pixels on and a vertical line of pixels off and repeat that across the screen, how resolvable those lines are is a principal determinant of true resolution, and hence image quality,” Pierce explained. “The better projectors will give you at least 25 percent measurable contrast between line pairs. With new digital technologies, you generally get much greater than that. The older CRTs are not nearly as good.”
Air Force simulators demand much higher resolution than is available in commercial high definition television (HDTV) systems, although military digital projector advancements often make use of the same innovations in LCD and digital light processing (DLP) technologies used in HDTV. A simulator would require a lot of commercial HDTV systems to create a full field of view at the resolution sought by Air Force commanders.
Good color balance also is important for simulation projectors, Pierce added. New laser projectors offer excellent color balance with a very wide color gamut. Old CRT technology could not offer nearly as many colors as new digital projectors. Moreover, complex simulations often require the use of a number of projectors to create an immersive environment “Once you put things in motion, you want a good temporal response for these pixels you are generating. Otherwise, the images start blurring in our retina,” Pierce explained. “As you are tracking objects with your eyeball, if the projector has a very slow pixel response, that imagery will start to blur on the retina. So you are spending a lot of money to get higher resolution and the last thing you need is something that looks great when it is stable but then when you start flying through it and doing maneuvers, everything starts blurring on you.”
Anything above six to eight milliseconds constitutes a slow response that could result in blurring on a screen, Pierce said. The AFRL and others examined this problem and published papers describing its causes in the late 1990s, but industry has caught up to the problem only in the past several years, he said. “Recent projector developments have produced systems with both higher resolvable pixel counts and faster response times that can support requirements for most Air Force simulator applications. Manufacturers continue to produce systems that are not only better, but are becoming more affordable.”
ENHANCING DLP PROJECTION
Christie Digital Systems USA Inc., based in Cypress, Calif., is launching what the company calls a revolutionary new product during the I/ITSEC in Orlando, during the first week of December.
Christie Digital Systems, a subsidiary of Japanese company Ushio, will unveil the first purpose-built simulation projector, Zoran Veselic, vice president of Visual Environments at Christie Digital Systems, told MT2.
“This product will fundamentally change the game and shift focus less on the product itself and more on how the product meets the requirements of the customer,” Veselic declared. “We are not in any way modifying the standard projector for conference rooms that many companies use with this projector. This new product is designed at 100 percent at Christie and was designed from the cradle with simulation in mind. The whole purpose of the projector is to address the requirements of the simulation market and nothing else.”
Tom Olechnowicz, Christie senior director of sales for visualization and simulation, cautioned the company could not go into more detail about the product before its release, but he emphasized that it would reduce the costs of maintenance and sustainability for projectors as well as fundamentally improve the performance of image displays.
Meanwhile, Olechnowicz said, Christie continues to focus on DLP as its preferred digital system. The company has been contracted to replace CRTs in airplane simulators with its digital systems in recent months. Christie replaced CRTs in the A-10 simulator program with its digital projectors, for example.
“We have acquired the capability to do night vision goggle stimulation,” for trainees. So it becomes important to balance colors across those multiple projectors as well so that the simulation is seamless and accurate. “We want them bright,” Pierce noted. “We want turnkey operations. We don’t want to have to individually take an hour or two to boot the system up because it’s a new emerging technology that takes a lot of care and feeding. We just like to flip a switch and then everything is functional right away.” Immersive simulations involve lots of moving objects designed to confront or distract the trainee. As these images move across a display, they must accurately depict the motion of enemy forces or other battle elements—which means they must avoid leaving the blurry tail of light often associated with fast moving objects on viewing displays. Olechnowicz reported. “We have the ability to reduce smearing, which tends to come about with any matrix projector. Anything that is not a CRT tends to have smearing associated with it. We have some technology that has been very successful in solving that problem.” Veselic pointed to the Christie technology known as Accu- Frame, the company’s proprietary anti-smearing solution.
“DLP technology has an optical arc without this technology that gives you an illusion of smearing behind fast-moving objects. Our technology, which is completely electrical and software inside our simulation projectors, eliminates smearing and tails behind fast-moving jets, for example,” Veselic said. “Some other people use devices to eliminate the smearing or use a mechanical solution. With DLP, we can do this electronically without any mechanical device.”
Christie also has developed its Multi-Blend solution for multiprojection applications, Veselic noted. This proprietary technology blends multiple projectors, for example, to properly display night scene simulations. Overlapping adjacent projector units increases the level of brightness, Veselic explained. The company customizes unique filters that are in front of the projection systems to eliminate any overlaps between multiple projectors.
Finally, Christie offers a unique technology called Auto-Cal, which minimizes costs of maintaining projectors for the company’s customers. The autocalibration system adjusts the brightness and color of an image across multiple projectors in a simulator, maximizing the performance of the overall system, minimizing the maintenance and minimizing the downtime of simulation devices.
“These three technologies are key in the use of DLP technology for simulation,” Veselic stated. “We believe DLP has the highest reliability level and a much better position for simulation than LCOS [liquid crystal on silicon]. Those two technologies change over time. DLP is truly digital and reflective, so there is no organic material in the DLP. The life of the simulation device stays at the same level as the same time when you purchased the simulator.”
EMBRACING LCOS PROJECTION
The military has held onto some CRT projectors over recent years because it had come to depend on some of the qualities CRT projectors offered that were not yet found in digital projectors. But now digital projectors have been catching up, thanks to innovations from companies like Belgium-based Barco.
“The military market lagged quite a bit,” Paul Lyon, Barco director of business development for simulation, told MT2. “The CRTs have really nice properties for night vision goggle stimulation and really good black levels for nighttime simulation scenes. Until recently, they had better resolution than the digital projectors. The military market hung onto the CRTs, and there are still hundreds and hundreds of CRT projectors in the military because they have really good qualities.”
CRTs largely remain better for the stimulation of night-vision goggles for testing them over many of the digital projectors available. But the consumer market has abandoned CRT projectors completely, driving repair and maintenance costs for those military CRT projectors way up as parts and expertise became scarce, Lyon observed.
“CRTs only last two or three thousand hours,” Lyon explained. “If you have a heavy simulator, that’s only a year or so and then you need one.”
To match the resolution and other properties of CRT projectors, Barco has turned to liquid crystal on silicon (LCOS), which it believes offers the most benefits for military simulation projectors. CRT projectors can offer two or three million pixels in its high-end units. Barco manufactures an LCOS projector called the Sim-7, which is a 3-million-pixel projector with a resolution of 2,048 pixels by 1,536 pixels.
The high pixel count found in an LCOS projector allows for flexibilities not found in other digital projectors, Lyon contended. For example, military trainers would like to project images on curved surfaces and the like to realistically simulate objects in the air and in other conditions. Warfighters could configure CRT images to adapt to those circumstances much easier than digital images.
“CRTs with their electron beam could shape the image on the CRT face,” Lyon described. “You could pre-distort the image so it would look correct projecting on a dome or a flat surface at a steep angle. You could get the electron beam to draw the shape you needed. The digital projectors have a fixed matrix. It’s a silicon chip in a rectangular format. You cannot distort that chip; it is a physical device.”
So to correct images for spherical surfaces or off-axis projection, trainers must distort imagery on the chip. That requires discarding some of the pixels in the image. But because projectors like the Sim-7 have such a high pixel count, discarding some of those pixels does not alter the quality of the projector’s performance.
Barco markets the Sim-7 to the military, where it is beginning to catch on, Lyon said. The projector has excellent properties for night-vision goggle stimulation. It has an unparalleled black level and a good brightness dynamic range. A CRT projector offers 250- 300 lumens of brightness at best, but the Sim-7 offers 2,000 lumens. The brightness is the result of arc lamps in the projectors, which start out much brighter than the phosphor inside a CRT projector.
Barco also produces a 10-million-pixel LCOS projector called the LX-5, which is quite expensive at present but permits unmatched applications. The company also manufactures DLP projectors, but they top out at 2 million pixels, limiting their use for training, Lyon noted.
“For flight simulators, there is always a demand for what we call eye-limited resolution,” he explained. “Even in ground simulation for tanks, the users would like their simulators to emulate the real world as much as possible. To really duplicate the resolution of the real world, you need huge amounts of pixels in your displays. LCOS has made that possible technologically.”
While opportunities for real-world resolution in a wide field of view are limited at present, Lyon predicted the projector market would meet the need within three to five years.
PROJECTOR’S BEST FRIEND
3D Perception Inc., with an office in Orlando, Fla., manufactures projector screen technology, but it also produces a box that attaches to other projects. The goal of the company, the U.S. branch of a Norwegian corporation, is to make any projector capable of operating as a simulation projector.
The product, called Compact UTM, is a PC-based box that provides image warping, edge blending, and color management for projectors that were not made for simulations, Mike Raines, 3D Perception president, told MT2. The features of the simulation therefore come in a box instead of within a purpose-built projector.
That offers customers quite a bit of flexibility as well as very high savings, Raines said. Customers are able to choose from a range of professional-grade projectors that can make use of the Compact UTM and thereby gain the ability to simulate environments with the projector combined with the box.
“In any curved screen display system, you need image warping, which maps the image to the geometry of the screen,” Raines commented. “The image has to be mapped to the curved screen so it looks correct from the pilot’s eye point. It’s not just one projector, but it’s multiple projectors—three, five, eight, 12 or whatever the requirements call for. You stitch those images together and create one continuous image through the system.”
One Compact UTM box sits between the image generator and the projector, enabling the use of commercial projectors from the likes of Canon, JVC or Sony for simulation purposes.
The device blends edges so that no gaps appear between projected images placed side by side. Operators overlap the images by perhaps five degrees and then vary the intensity in the blend zone to keep an even intensity across the entire picture. In addition, matching colors between projectors and to real-world items becomes very important of the accuracy of simulation training, Raines added. “Basically, whether it is in our box or in an image generator— mostly in the commercial airline world—this functionality needs to be somewhere,” he remarked. “Historically, this capability has been built into projectors.”
Projector manufacturers mass produce non-simulation projectors for use by commercial markets, selling them to a wide variety of businesses. This high volume creates a large supply of high-quality digital projectors, which are generally very affordable.
“Logistically, instead of thinking about how to repair a simulation specific projector for many years because simulators are in service for 15 or 20 years or more, you could replace the whole projector for a very low cost,” Raines stated. “The new projector has the same 16x9 aspect ratio, excellent black levels, smear reduction technology, excellent color performance and reproduction.”
Enabling the ability to use any high-end projector provides warfighters with the opportunity to tap into the mass projector market and take advantage of it, Raines argued. “It’s a different way of thinking about it. It’s new. It’s just not about the perfect technical solution. There are also logistics and cost aspects and taking advantage of the mass market,” he said. ♦