Equipe Simulation Visualising Your Imagination

1. This presentation specifically looks at the current FAA / JAA level D (flight simulation) criteria and asks how the visual display elements may be met using LOW COST digital projection technology. This presentation specifically looks at the current FAA / JAA level D (flight simulation) criteria and asks how the visual display elements may be met using LOW COST digital projection technology.

3. What is driving the desire to have increased resolution in terms of pixel count? Is this being driven to the Level D criteria? Is there research to suggest that increased resolution alone provides for a more accurate, immersive simulation with proven enhancements to pilot / aircrew training? Or is it in fact being driven by the display industry based around what TECHNOLOGY can offer and the natural �feeling� that increased resolution leads to better training? (�we can supply super high resolution projection�..and this MUST enhance pilot training��right?�). This presentation hopefully takes a more measured look at the Level D requirements themselves and asks what it required to specifically achieve them. What is driving the desire to have increased resolution in terms of pixel count? Is this being driven to the Level D criteria? Is there research to suggest that increased resolution alone provides for a more accurate, immersive simulation with proven enhancements to pilot / aircrew training? Or is it in fact being driven by the display industry based around what TECHNOLOGY can offer and the natural �feeling� that increased resolution leads to better training? (�we can supply super high resolution projection�..and this MUST enhance pilot training��right?�). This presentation hopefully takes a more measured look at the Level D requirements themselves and asks what it required to specifically achieve them.

4. Since we are talking about using digital projection to achieve level D, only the latency and visual system specific requirements will be discussed. Latency is generally a function of the IG & image correction system rather than the projection technology, however some projection technology, specifically DLP, introduces a delay therefore the impact that this has on overall latency will be discussed.Since we are talking about using digital projection to achieve level D, only the latency and visual system specific requirements will be discussed. Latency is generally a function of the IG & image correction system rather than the projection technology, however some projection technology, specifically DLP, introduces a delay therefore the impact that this has on overall latency will be discussed.

5. JAR-STD 1A visual requirements geared toward Raster Calligraphic CRT�s. Of these requirements, it is the generation of realistic, compliant light points that is the limiting factor in the adoption of digital projection as a raster calligraphic CRT replacement.JAR-STD 1A visual requirements geared toward Raster Calligraphic CRT�s. Of these requirements, it is the generation of realistic, compliant light points that is the limiting factor in the adoption of digital projection as a raster calligraphic CRT replacement.

7. Once every frame, the background raster image is drawn. This simply draws the polygonal content of the scene (buildings, aircraft, trees etc). At 60hz, this needs to be drawn 60 times every second, giving a frame time of 16ms. The time taken by the raster scan will be less than this 16ms limit, giving �Free� time before the next scan must commence (typically 2ms). During this time, the individual light points are drawn by focussing the electron beam at specific points on the display. Since there are only a very small number of points required (2000 points in a day scenario, as opposed to 1.3 million pixels in the raster) each point can be focused on for a far greater time than an individual pixel within the raster scan, giving a far greater intensity and very high contrast between the point and the underlying raster image. (It is also common for the display to be interlaced, meaning that odd numbered raster lines are drawn, followed by half the light points (in 8ms), and then the even raster lines followed by the remaining light points). This method of operation is UNIQUE to raster calligraphic projection, all other projection technology is raster only (with the possible exception of some developmental laser systems). Please note that the statement �Raster Only� when applied to digital projectors is inaccurate, these projectors do not raster scan in the way that CRT projectors do. For the purposes of this presentation however it is simpler to consider their operation as �raster scan� since they are only capable of displaying the �raster� portion of the CRT display (the way they do this is largely irrelevant so far as we are concerned here)Once every frame, the background raster image is drawn. This simply draws the polygonal content of the scene (buildings, aircraft, trees etc). At 60hz, this needs to be drawn 60 times every second, giving a frame time of 16ms. The time taken by the raster scan will be less than this 16ms limit, giving �Free� time before the next scan must commence (typically 2ms). During this time, the individual light points are drawn by focussing the electron beam at specific points on the display. Since there are only a very small number of points required (2000 points in a day scenario, as opposed to 1.3 million pixels in the raster) each point can be focused on for a far greater time than an individual pixel within the raster scan, giving a far greater intensity and very high contrast between the point and the underlying raster image. (It is also common for the display to be interlaced, meaning that odd numbered raster lines are drawn, followed by half the light points (in 8ms), and then the even raster lines followed by the remaining light points). This method of operation is UNIQUE to raster calligraphic projection, all other projection technology is raster only (with the possible exception of some developmental laser systems). Please note that the statement �Raster Only� when applied to digital projectors is inaccurate, these projectors do not raster scan in the way that CRT projectors do. For the purposes of this presentation however it is simpler to consider their operation as �raster scan� since they are only capable of displaying the �raster� portion of the CRT display (the way they do this is largely irrelevant so far as we are concerned here)

8. Only raster calligraphic CRT�s draw light points calligraphically during the fly-back phase of the interlaced raster display. Since other projectors do not have this calligraphic capability the functionality it provides MUST be achieved within the raster.Only raster calligraphic CRT�s draw light points calligraphically during the fly-back phase of the interlaced raster display. Since other projectors do not have this calligraphic capability the functionality it provides MUST be achieved within the raster.

9. Raster Calligraphic CRT projection has a number of advantages in terms of image quality, as well as having the capacity to provide calligraphic light points. However they are expensive and complex devices which require costly and time consuming maintenance. A failure in the low voltage deflection amp is likely to destroy the CRT raster which will then require replacement at several thousand Euros per tube. To achieve 6 foot lamberts the tubes have to be driven very hard which results in probable tube replacement prior to annual recertification. They are extremely heavy which causes handling problems during install and maintenance, as well as contributing to the overall weight of the sim which drives the need for powerful motion basis (largely hydraulic, which leads to environmental concerns and again demands highly skilled maintenance). They require high voltages which could be considered hazardous. If it is possible to replace them with cheap, light weight digital systems that replace tubes with lamps (that take about 10 minutes to replace, not several hours) and just don�t require hundreds of highly skilled hours to maintain alignment, while still meeting Level D requirements then the benefits will be obvious. Raster Calligraphic CRT projection has a number of advantages in terms of image quality, as well as having the capacity to provide calligraphic light points. However they are expensive and complex devices which require costly and time consuming maintenance. A failure in the low voltage deflection amp is likely to destroy the CRT raster which will then require replacement at several thousand Euros per tube. To achieve 6 foot lamberts the tubes have to be driven very hard which results in probable tube replacement prior to annual recertification. They are extremely heavy which causes handling problems during install and maintenance, as well as contributing to the overall weight of the sim which drives the need for powerful motion basis (largely hydraulic, which leads to environmental concerns and again demands highly skilled maintenance). They require high voltages which could be considered hazardous. If it is possible to replace them with cheap, light weight digital systems that replace tubes with lamps (that take about 10 minutes to replace, not several hours) and just don�t require hundreds of highly skilled hours to maintain alignment, while still meeting Level D requirements then the benefits will be obvious.

11. This calculation, while mathematically correct, doesn�t take into account certain elements of projection onto a curved display (collimated or otherwise), it assumes that the projection surface is uniformly flat which obviously isn�t the case within a curved collimated display. However, this resolution calculation is proven to be accurate enough to offer a guideline. This calculation, while mathematically correct, doesn�t take into account certain elements of projection onto a curved display (collimated or otherwise), it assumes that the projection surface is uniformly flat which obviously isn�t the case within a curved collimated display. However, this resolution calculation is proven to be accurate enough to offer a guideline.

12. The �Light Valve� refers to the way that light intensity is controlled, and is currently LCD, LCoS or DLP. While LCD and LCoS appear similar in terms of operation, they are in fact quite different technologies. Another projector type that may be suitable for Level D certification is Laser, however this takes a fundamentally different approach and is realistically still a developmental technology, which is likely to be �some years� away from achieving stability for this type of application (low power, monochrome units are currently available, however these are an entirely different beast to what would be required to achieve level D). The �Light Valve� refers to the way that light intensity is controlled, and is currently LCD, LCoS or DLP. While LCD and LCoS appear similar in terms of operation, they are in fact quite different technologies. Another projector type that may be suitable for Level D certification is Laser, however this takes a fundamentally different approach and is realistically still a developmental technology, which is likely to be �some years� away from achieving stability for this type of application (low power, monochrome units are currently available, however these are an entirely different beast to what would be required to achieve level D).

13. I am aware that there is one airline that is experimenting with laser projection but this technology IS expensive and unproven, it certainly could not be considered low cost - or even a guaranteed way of achieving Level D certification. Laser projection in general still has a way to go before it reached technical and economic viability and is therefore not discussed in detail. I am aware that there is one airline that is experimenting with laser projection but this technology IS expensive and unproven, it certainly could not be considered low cost - or even a guaranteed way of achieving Level D certification. Laser projection in general still has a way to go before it reached technical and economic viability and is therefore not discussed in detail.

14. LCoS chips can be considered to be LCD panels on top of a reflective coating. In the same way as with LCD, pixel intensity is controlled by polarising the LCD substrate to allow specific amounts of light to pass through. It differs from LCD in that this light is reflected from a mirror sub layer and through the lens, rather than directly through the lens as with LCD. LCoS achieves a very small inter-pixel gap which leads to a very smooth, seamless image that removes any discernable pixilation and therefore removes the �Screen Door� effect common to LCD, and is capable of producing extremely high resolutions up to QXGA (2048 x 1536). However since it is largely LCD based it natively suffers from poor contrast ratio�s which may preclude its suitability for Level D certification. This has been addressed by a number of manufacturers that have boosted the contrast ratio to very high levels (10,000 � 15,000:1 reported). LCoS chips are also reportedly difficult to manufacture with production yields being fairly low (Intel scrapped it production for this reason). This may lead to concerns over failures and availability, and may dictate a higher cost for such systems (considering that at least 3 panels are required for each projector). LCoS chips can be considered to be LCD panels on top of a reflective coating. In the same way as with LCD, pixel intensity is controlled by polarising the LCD substrate to allow specific amounts of light to pass through. It differs from LCD in that this light is reflected from a mirror sub layer and through the lens, rather than directly through the lens as with LCD. LCoS achieves a very small inter-pixel gap which leads to a very smooth, seamless image that removes any discernable pixilation and therefore removes the �Screen Door� effect common to LCD, and is capable of producing extremely high resolutions up to QXGA (2048 x 1536). However since it is largely LCD based it natively suffers from poor contrast ratio�s which may preclude its suitability for Level D certification. This has been addressed by a number of manufacturers that have boosted the contrast ratio to very high levels (10,000 � 15,000:1 reported). LCoS chips are also reportedly difficult to manufacture with production yields being fairly low (Intel scrapped it production for this reason). This may lead to concerns over failures and availability, and may dictate a higher cost for such systems (considering that at least 3 panels are required for each projector).

15. LCoS is a relatively new technology based around LCD technology. It offers very high resolution in advance of standard DLP, and produces a very smooth seamless image. High end systems produce extremely high contrast ratios (10,000 to 15,000:1) - potentially in advance of what of what would be required to achieve Level D compliant light points, however this is achieved with technology that is proprietary in nature, and does not represent COTS. LCoS does offer a good alternative to raster calligraphic projection, however in general terms it is expensive due to its complex nature � certainly the most expensive system by far when compared to DLP. It is also likely that repair / parts replacement would be expensive due to the nature of the optical engine. The nature of the analogue control over the LCD substrate may also give some cause for concern. One of the problems with CRT was keeping the colour matched between channels due to fluctuations within the analogue control voltage to each tube within the CRT caused by variations in ambient temperature, humidity etc � analogue voltages are very difficult to control with high accuracy. While the voltages controlling the LCD substrate of each LCoS panel (and therefore the colour level (�shade�) output) are much lower than those driving a CRT, they are never the less analogue in nature and may fluctuate giving colour variations between projectors. (see Projection Technology in Digital Cinema by Michael Karagosian) LCoS is a relatively new technology based around LCD technology. It offers very high resolution in advance of standard DLP, and produces a very smooth seamless image. High end systems produce extremely high contrast ratios (10,000 to 15,000:1) - potentially in advance of what of what would be required to achieve Level D compliant light points, however this is achieved with technology that is proprietary in nature, and does not represent COTS. LCoS does offer a good alternative to raster calligraphic projection, however in general terms it is expensive due to its complex nature � certainly the most expensive system by far when compared to DLP. It is also likely that repair / parts replacement would be expensive due to the nature of the optical engine. The nature of the analogue control over the LCD substrate may also give some cause for concern. One of the problems with CRT was keeping the colour matched between channels due to fluctuations within the analogue control voltage to each tube within the CRT caused by variations in ambient temperature, humidity etc � analogue voltages are very difficult to control with high accuracy. While the voltages controlling the LCD substrate of each LCoS panel (and therefore the colour level (�shade�) output) are much lower than those driving a CRT, they are never the less analogue in nature and may fluctuate giving colour variations between projectors. (see Projection Technology in Digital Cinema by Michael Karagosian)

16. DLP has two variants, single chip and three chip. 3 chip is used in high end cinema applications (and some simulators) but while giving unsurpassed image quality, it is bulky and expensive. Here we are interested in achieving level D with current low cost digital projection so only the single chip variant will be discussed. Within single chip DLP the image is produced by reflecting light from a DMD (digital micro-mirror device). This DMD is formed of an array of individual mirrors which can be angled to reflect light through the lens (and onto the screen) or away from the lens onto a light absorbent surround. The time that each individual mirror is reflecting light onto the screen dictates the brightness of each individual pixel (since there is one mirror per pixel). Colour is introduced by first passing the light through a rapidly rotating colour wheel, and synchronising the mirror reflection time for each colour, thus building a full colour image. The use of this colour wheel has caused a potential for colour breakout to be discernable in certain circumstances, however recent advances have more or less countered this negative effect by introducing additional colours into the wheel providing a smoother, less abrupt colour change (and also improving colour saturation). DLP has two variants, single chip and three chip. 3 chip is used in high end cinema applications (and some simulators) but while giving unsurpassed image quality, it is bulky and expensive. Here we are interested in achieving level D with current low cost digital projection so only the single chip variant will be discussed. Within single chip DLP the image is produced by reflecting light from a DMD (digital micro-mirror device). This DMD is formed of an array of individual mirrors which can be angled to reflect light through the lens (and onto the screen) or away from the lens onto a light absorbent surround. The time that each individual mirror is reflecting light onto the screen dictates the brightness of each individual pixel (since there is one mirror per pixel). Colour is introduced by first passing the light through a rapidly rotating colour wheel, and synchronising the mirror reflection time for each colour, thus building a full colour image. The use of this colour wheel has caused a potential for colour breakout to be discernable in certain circumstances, however recent advances have more or less countered this negative effect by introducing additional colours into the wheel providing a smoother, less abrupt colour change (and also improving colour saturation).

17. Since DLP is a reflective technology forming the image from very rapidly moving mirrors with very accurate control over the reflection period, very high contrast levels may be achieved (up to 7500:1), and since light loss is minimal (light is reflected directly through the lens) DLP projectors are able to produce very high brightness. They offer native resolutions of up to 1080p (1920 x 1080) within a single chip. Unlike LCoS they are a true �digital� technology (a mirror is either on or off, reflecting light or not reflecting light, with no intermediate steps) and therefore don�t suffer from potential voltage fluctuations. DLP projectors, even high end units ARE inexpensive when compared to high end LCoS units and offer potentially much lower maintenance costs since they are optically less complex. On the negative side single chip variants do produce a �rainbow� effect caused by the way in which colour is generated. This leads to certain users being able to discern individual colours (red, green and blue) within a projected frame. This situation has however been greatly improved in a number of ways, for example by introducing additional colours into the colour wheel to reduce the �abruptness� of the colour change (instead of changing directly from red to green for example these wheels will change from red to yellow and then on to green). This also has the effect of reducing the time that each colour is displayed within each frame, causing a faster �pulse� which is less likely to be visible. Since DLP is a reflective technology forming the image from very rapidly moving mirrors with very accurate control over the reflection period, very high contrast levels may be achieved (up to 7500:1), and since light loss is minimal (light is reflected directly through the lens) DLP projectors are able to produce very high brightness. They offer native resolutions of up to 1080p (1920 x 1080) within a single chip. Unlike LCoS they are a true �digital� technology (a mirror is either on or off, reflecting light or not reflecting light, with no intermediate steps) and therefore don�t suffer from potential voltage fluctuations. DLP projectors, even high end units ARE inexpensive when compared to high end LCoS units and offer potentially much lower maintenance costs since they are optically less complex. On the negative side single chip variants do produce a �rainbow� effect caused by the way in which colour is generated. This leads to certain users being able to discern individual colours (red, green and blue) within a projected frame. This situation has however been greatly improved in a number of ways, for example by introducing additional colours into the colour wheel to reduce the �abruptness� of the colour change (instead of changing directly from red to green for example these wheels will change from red to yellow and then on to green). This also has the effect of reducing the time that each colour is displayed within each frame, causing a faster �pulse� which is less likely to be visible.

18. The Level D requirements specify a delay of Less Than 150ms between a pilot input and the simulator responding. When a pilot moves the control column for example, this input is fed to the simulator host, which then calculates the nature of the input and the correct reaction of the avionics. This data is then passed to the motion and control loading computer which converts the signal to an input to the motion base to move the simulator (and apply the correct resistance to the control column). Simultaneously this data is passed to the visual IG which calculates the correct response of the display, and feeds video data to the display device (via the image correction computer) thus producing the correct change in the displayed image. The largest delay is typically caused by the host since it is responsible for the majority of the computations, however the motion and control loading system will also introduce a delay since certain mechanical systems take time to react over and above the mathematical calculations performed by the motion computer (hydraulic pumps may need to ramp up for example, and the motion actuators take a short time to react). This delay MUST occur before any display change is completed, if the visual moves before the motion base responds to the input severe motion sickness may result (even for an experienced combat pilot). The time between the host communicating with the motion system and the motion base responding can be considered a Mandatory delay, that is a period of time during which the visual MAY NOT update. While this period is less than the 16ms delay introduced by a DLP system, it never the less offsets it a little and brings the inherent delay down below around 10Ms. There are a great many simulator hosts and motion systems operating at Level D, some of which are quite old and comparatively slow. Even with older systems however the overall delay (host, motion AND IG) is typically less than 100ms, meaning that an additional delay of <10ms is still WAY within tolerance. The 1 frame delay caused by DLP has in no way caused concern over Level D acceptability. The comparison between the DLP delay and the �delay� inherent within CRT�s is entirely accurate � from an observational perspective there is no difference. However, it is convenient for CRT that FAA / JAA latency tests measure the time from pilot input to START of frame display not frame COMPLETE, giving the common, inaccurate belief that CRT is quicker than DLP. DLP buffers the frame in its entirety and displays it in one go rather than building it up a pixel at a time, and this has been done intentionally to remove any possibility of frame �tear�. The Level D requirements specify a delay of Less Than 150ms between a pilot input and the simulator responding. When a pilot moves the control column for example, this input is fed to the simulator host, which then calculates the nature of the input and the correct reaction of the avionics. This data is then passed to the motion and control loading computer which converts the signal to an input to the motion base to move the simulator (and apply the correct resistance to the control column). Simultaneously this data is passed to the visual IG which calculates the correct response of the display, and feeds video data to the display device (via the image correction computer) thus producing the correct change in the displayed image. The largest delay is typically caused by the host since it is responsible for the majority of the computations, however the motion and control loading system will also introduce a delay since certain mechanical systems take time to react over and above the mathematical calculations performed by the motion computer (hydraulic pumps may need to ramp up for example, and the motion actuators take a short time to react). This delay MUST occur before any display change is completed, if the visual moves before the motion base responds to the input severe motion sickness may result (even for an experienced combat pilot). The time between the host communicating with the motion system and the motion base responding can be considered a Mandatory delay, that is a period of time during which the visual MAY NOT update. While this period is less than the 16ms delay introduced by a DLP system, it never the less offsets it a little and brings the inherent delay down below around 10Ms. There are a great many simulator hosts and motion systems operating at Level D, some of which are quite old and comparatively slow. Even with older systems however the overall delay (host, motion AND IG) is typically less than 100ms, meaning that an additional delay of <10ms is still WAY within tolerance. The 1 frame delay caused by DLP has in no way caused concern over Level D acceptability. The comparison between the DLP delay and the �delay� inherent within CRT�s is entirely accurate � from an observational perspective there is no difference. However, it is convenient for CRT that FAA / JAA latency tests measure the time from pilot input to START of frame display not frame COMPLETE, giving the common, inaccurate belief that CRT is quicker than DLP. DLP buffers the frame in its entirety and displays it in one go rather than building it up a pixel at a time, and this has been done intentionally to remove any possibility of frame �tear�.

19. Both LCoS and DLP are very good technologies, and both have been proven to be suitable CRT replacements. Both LCoS and DLP are very good technologies, and both have been proven to be suitable CRT replacements.

20. However, if cost is a factor (and lets face it, when is it not?) then DLP offers a potential cost saving��.However, if cost is a factor (and lets face it, when is it not?) then DLP offers a potential cost saving��.

21. ��.and this cost saving may be significant��.and this cost saving may be significant

22. As a simulation specific projector manufacturer Equipe Simulation have a proven record of meeting the Level D criteria with DLP. As such we are developing a simulation specific DLP based projector that offers higher native resolution than previously available with the explicit aim of meeting the level D requirement within a reduced channel count. TXGA at 1920 x 1400. As a simulation specific projector manufacturer Equipe Simulation have a proven record of meeting the Level D criteria with DLP. As such we are developing a simulation specific DLP based projector that offers higher native resolution than previously available with the explicit aim of meeting the level D requirement within a reduced channel count. TXGA at 1920 x 1400.