WATS Presentation

1. WATS Presentation Multi-projector displays using commercial of the shelf (COTS) projectors Andrew Jamison CEO, Scalable Display Technologies

2. Example Case: 50 COTS HD projectors on a 40’ dome Message: “It’s all about the system solution”…

3. The system as a “pixel pipeline” Image Generator Warping Function Projector Screen • COTS “home cinema” projectors • Color correction/control • Light/black levels • Color depth (10 bit) • Geometry correction • Accuracy & warp location • A word on texture filtering

4. Color Correction/Control Three projector illustration • Projector color calibration is a requirement • Projector must have Ethernet connection & knobs to turn • Serial connections work but require more parts in the system • Set projector in “cinema mode” • Two approaches to calibrate color • Shaders – send corrected pixels to the projector “input” • Correct the projectors “output” – modify settings of the projector Available dynamic range 1 2 3 1 2 3 Projector “output” Corrected “Input” only Correction

5. Color Calibration Trade-offs • Input side • Offers opportunity for localized correction of “hot spots” and other aberrations • Faster to calibrate • One weak lamp can drag down the performance of the entire array • “Lowest common denominator” • Output side • Maximizes dynamic range of array • More difficult to execute • Requires communication with each individual projector make and model • Takes longer to calibrate

6. “Output” approach considerations • There are two typical methods to control projectors remotely • “menu based” control • Mimic a remote control • Slow and subject to missed commands • “value based” control • Can receive specific values • Much faster and more accurate Ask your vendor to provide “value based” control

7. Light/black levels • First consider impact of screen shape/finish • Part 60 4.d – surface contrast ratio – 5:1 • cross reflectance…1 lux of ambient light (i.e. a small candle), the max perceivable contrast ratio is 500:1. A dimly lighted room with 30 lux of lighting would squash the maximum perceivable contrast ratio to 50:1 • “Black Level” – no more than .015 candelas/square meter (cd/m²) in an unlit portion of a displayed scene as measured from the pilot eye-point. • Contrast ratio of projectors • Low contrast results in low resolution but high contrast does not necessarily mean high resolution • High CR is a good goal but be careful of marketing numbers…did it say ANSI? • Look for iris and iris controls • Brightness • 4.e - Not less than six (6) foot-lamberts (20 cd/m2).

8. Black level challenge Edge-blended “tiled” example Projector 1 Projector 2 Shared pixels and elevated black here Projector 3 Projector 4 High contrast ratio projectors are required for good blends Area of maximum shared light

9. Color depth 10 Bit color through the entire pipeline makes for brilliant displays

10. Geometry Calibration • Objective is to align the pixels and blend the edges • Manual calibration • Practical and cost-effective for some scenarios • Small arrays and flat screen • Advanced tools are available but challenges persist • Fully automatic calibration • Domes, cylinder and other complex geometries are very difficult to correct manually • Fast, reliable and flexible

11. Geometric Accuracy • 4.c - System Geometry – • 5° even angular spacing within ±1° as measured from either pilot eye point and within 1.5° for adjacent squares. • Uniformity of a grid as measured by theodolite • 6.e - The visual system must be free from optical discontinuities and artifacts that create non-realistic cues. • Geometric mesh must be free of aberrations or discontinuities • Some manual approaches suffer from this…

12. Geometric warping location • Three places to execute geometric warping • Projector • External box • IG • External box and projector warping • “application independent” • Can be fully automatic • Possibility for good filtering • IG warping • “application dependent” – requires SDK integration • Truly zero latency since warp is within the 16ms render cycle – (typically .15ms) • Also consider aliasing artifacts

13. Texture Filtering Basics Better quality re-sampling = better quality images Polynomial interp. Nearest neighbor Linear interpolation

14. A view on resolution • 4.f – Not greater than two (2) arc minutes (per pixel). F Horizontal Field Of View ~ 143 degrees Comparable to 50mm lens (8,400 arc minutes) 4,200 unique pixels needed ~ 5,000 projected pixels Including overlap 1 arc minute = .3 milliradians Each pixel = .6milliradians Sony – 4K pixels / 100°

15. One radian is the anglesubtended at the center of a circle by an arc that is equal in length to the radius of the circle. 1 radian = 57.3°

16. Graphic Cards Allow for Resolution Higher • Multi-GPU technology (Vista only) • nVidia's 'SLI' • ATI's 'Crossfire‘ • Quad output cards • Pixel shader abilities

17. It’s a system • Points of failure are: • Cables • Connectors • Power supplies • Simulators/FTD are controlled environments • Know screens, IGs, projectors • These are repeatable environments

18. 4 Projector Dome, 220 Degrees.

19. Thank you