Image Generator Developments
Written by Erin Flynn Jay
DOD WANTS TO TAKE ADVANTAGE OF THE RECENT BREAKTHROUGHS IN IMAGE GENERATOR TECHNOLOGY AS THEY BECOME MORE READILY AVAILABLE AND AFFORDABLE.
A shortfall the government has when dealing with the latest image generators (IGs) is that there will always be performance tradeoffs and compromises no matter which system they select based on what’s vital to a particular training application. Aechelon Technology, Concurrent Computer Corp. and Wegmann USA have new IGs on the market that address critical training conditions. The IG’s purpose in a visual display system is to depict a training environment as realistically as possible while meeting the training requirements. IGs play a key role in creating a positive training experience for the trainee.
Many IGs on the market offer medium- to high-fidelity representations of environmental factors, which are an integral part of training. “In a flightbased simulator, volumetric clouds and fog can add depth to a scene,” said Ryan D. McIntire, visual engineer on the AVCATT program that is handling the replacement of the IG in the AVCATT. “Particle-based rain and snow can take into account wind velocity and direction to simulate visibility reduction in bad weather scenarios.”
For programs that rely on shipboard operations, there are solutions that provide 3-D sea states with real-time reflections and ship wakes that conform to the ocean’s surface. For low flight operations some systems are able to support moving grass and trees that can offer enhanced speed and depth cues. In addition, particle-based rotor wash and brownout are also offered on some systems. “This adds a high level of realism to a condition that can cause a loss of situational awareness leading to accidents during landing and takeoff operations,” said McIntire. “You will also find that many DoD programs are now requiring the synchronous rendering of multiple channels in both visual and non-visual spectrums.” Looking to the future and what the DoD will require with regard to IGs, McIntire said the government wants to take advantage of many of the recent breakthroughs in IG technology noted above as they become more readily available and affordable. “The customer wants the most realistic environment possible—period. We strive to create environments where the trainee wants to learn,” he said. “Our goal is to provide the most realistic training environment in order to suspend disbelief while meeting our training requirements.”
An important focus to consider when purchasing IG hardware is to procure hardware that is primarily commercial off-the-shelf (COTS). This can reduce the cost that the government spends on both the acquisition of the hardware itself as well as life cycle operating cost.
“Many image generation systems today can address our critical training conditions at some capacity,” said McIntire. “However, one of the shortfalls that one will find when dealing with any of the latest IGs is that there will always be performance tradeoffs and compromises no matter which system you choose to go with based on what’s vital to the particular training application [ground, high flight, low flight, maritime, etc.].”
ULTRA-HIGH ELEVATION RESOLUTION
In December 2008, Aechelon Technology delivered its 100th high-end trainer visual system and announced number 120 was on order. Most recently, the company introduced its pC-NOVA v4.6 Image Generator. “The key enabling feature is supporting ultra-high terrain elevation resolution in real time and not just terrain imagery,” said Javier Castellar, director of programs at Aechelon Technology Inc.
This new family of image generators is reaching above 1 million polygons per frame at 60 Hz and can render beyond digital terrain elevation data Level 3 with all features enabled. Aechelon Technology has already deployed these systems in programs with country size areas of interest that provide unprecedented foreign area familiarization exclusively for U.S. forces worldwide. Another key feature that further improves training and mission familiarization is unrestricted and accurate real-time terrain and feature shadows while sustaining the new terrain resolution. “Unlike other systems, the devices can render in real-time shadows even at very low angles of the sun and the moon at the time of the mission,” said Castellar. “Another area of improvement is support for very rapid database updates, even for very large databases. Currently our database team routinely manages hundreds of terabytes in existing programs.”
Aechelon Technology has focused on resolving the most challenging training needs beyond the visible spectrum: conditions that limit or impair the sensor operation of night vision goggles, color CCDs, advanced FLIRs and low level TV systems. “Weather and moon/sun locations that make sensor operation harder have been the focus of our R&D efforts with direct input from the end-user operator rather than market and industry trends,” said Castellar. “The fact that our sensor architecture allows for spectral rendering combined with a sensor independent database system provides an accurate perception of terrain when linked with ephemeris models. Our pure software-based solution has paid off and will keep improving with newer COTS hardware.”
Aechelon Technology decided by design since its pCNova introduction to only use truly COTS cards. This has enabled Aechelon Technology to stay on the top of the performance by avoiding delays of one more generation if the COTS cards were to be customized. Aechelon Technology has not necessitated sensor hardware postprocessors thanks to the reliance on software/ GPU-based approaches to sensor rendering. “This innovative approach that we started almost a decade ago has allowed us to remain with gaming COTS hardware even in the most complex configurations,” said Castellar.
Aechelon Technology routinely upgrades its systems as new COTS hardware comes to the market but has the policy of not announcing new products until they are available. Typically Aechelon Technology enjoys very early access to COTS hardware before it is announced, enabling testing and validation before the new hardware hits the street.
HIGH-PERFORMANCE GRAPHICS
In December 2008, Concurrent announced a new member to its PC-IG family— ImaGen RL, offering high-performance graphics in a compact 1U (1.75 in.) package. ImaGen visual servers are powered by Concurrent’s real-time RedHawk Linux operating system for the highest image fidelity.
The improvement over earlier ImaGen models is the ease of rack or stack integration into synthetic environments where space restrictions exist. Multiple ImaGen RL visual servers may be stacked with an Ethernet switch in a 14U rackmount enclosure for added flexibility. “Software rendering applications that simulate complex environmental scenarios can achieve maximized realism when executing on a highly deterministic, realtime image generation platform,” said Ken Jackson, vice president, Real-Time Development and Concurrent Special Systems for Concurrent Computer Corp. This is where Concurrent’s Imagen IG powered by Red- Hawk Linux comes in by delivering the required real-time performance and seamless response for an improved training experience. Concurrent’s NightStar tools enable IG software developers to tune their visual rendering applications to more closely match real-world conditions.
The ImaGen family of visual servers can be custom configured to address a wide range of price/performance requirements featuring the latest in COTS gaming industry graphics such as the high-performance NVIDIA Quadro FX 5800. Concurrent’s RedHawk Linux OS includes I/O drivers that have been enhanced to ensure real-time deterministic response. Proprietary drivers such as the popular drivers from NVIDIA have been enhanced and are included.
Concurrent plans to add ImaGen Visual Server support for Intel’s latest-generation Nehallem microarchitecture offering more powerful I/O performance for enhanced realism.
DYNAMIC TERRAIN SUPPORT
MilCIG3, the next-generation IG from Wegmann USA, is a significant improvement over the already successful and powerful Mil- CIG2. This release introduces several features and enhancements in the broad categories of improved database handling and installation, integration, performance and visual feature support.
MilCIG3 enhances the installation and handling of terrain and model databases in the following ways:
• Databases can be installed separately from the MilCIG3 application.
• Terrains can be changed/reloaded faster and without requiring a restart of the IG.
• Uses a unified model database, which contains all vehicles, characters, etc.
• Individual models are loaded dynamically on demand.
• Includes a database preprocessing tool to convert OpenFlight and Maya 3-D models to optimized binary format for IG
“In the area of improved integration, MilCIG3 configuration is XML-based, uses distributed interactive simulation protocol for communication with other subsystems, and simplifies network configuration and traffic related to the IG,” said Don Kemper, manager, training and simulation for Wegmann USA. “This release also introduces an integrated stealth viewer for the display of any visual channel of any simulator in the system; previous versions required separate subsystems for each stealth viewer.”
MilCIG3 supports dynamic structures, animation and modification of static terrain and database objects such as buildings, trees and other obstacles in the environment. This includes detailed damage models for buildings, switchable states for static database objects like trees and the ability to set houses and dynamic objects on fire. Dynamic terrain features support the run-time addition, modification and deletion of various terrain features, such as craters, trenches, embankments, barbwire and mines.
This dynamic terrain support is not merely a change in the texture that is displayed. “For example, adding a crater actually modifies the terrain mesh and adds the appropriate texture. This means that a vehicle can react accordingly when attempting to drive over a crater; a tracked vehicle may drive over it, a wheeled vehicle may become stuck and a human may walk into and out of the crater,” said Kemper. Similarly, damaged buildings produce rubble, which then becomes obstacles in the synthetic environment.
Visual effects include improved lighting and shadow effects using light sources for street lights, etc., and cascaded shadow maps with filtering for enhanced shadows. Special effects such as fire, smoke, rain, snow, dust, muzzle flashes and ammunition effects (smoke, tracers, flares, etc.) are implemented as particle systems within the IG. Various subeffects for impacts and explosions are supported, such as hit flash, fire cloud, dust/smoke and water splashes.
MilCIG3 supports numerous weather and environment control options such as rain and snow particle effects, and wind effects (seen via dust, smoke and tree animations). The realism of the training environment is enhanced by these particle effects in subtle but critical ways. “For example, in our driving simulators the rain and snow particle effects affect the driver’s view by collecting and moving on the windshield in response to motion and windshield wipers. Part of the strategy is to make extensive, yet optimal, use of lighting effects, shadow effects, fog, haze, cloudiness, sun glare and wind to further enhance the realism of the synthetic environment,” said Kemper.
Another significant part of the strategy is dynamic terrain as previously discussed. The ability to dynamically modify the terrain both visually and physically affords the opportunity for an improved training experience. Consider an impact crater or trench created in the path of a trainee’s vehicle: what is the training effect when the operator drives over it as is the case with static terrain environments vs. the effect of falling into it as could happen with MilCIG3’s dynamic terrain.
The ability to run on COTS PCs and COTS graphics cards targeted at gaming was a key design requirement and a cornerstone in the MilCIG3 design. Additionally, it does not rely on any third-party software, allowing new hardware features to be supported relatively quickly. Although MilCIG3 supports a wide range of COTS graphics hardware, this release is performance optimized for the Nvidia DX10 hardware with best performance on GeForce 8xxx, 9xxx, GTX 2xx series’ graphic processors.
“We bundle all product updates and enhancements, driven from product development and customer requirements, into major products releases twice a year,” Kemper concluded. “The next product release, which includes MilCIG3, is scheduled for April 30, 2009. The second release for 2009 is scheduled for October 31.” ♦