Making Online Video Advertising Smart' Timely' Relevant'

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WATS Presentation
Multi-projector displays using commercial of the
shelf (COTS) projectors Andrew Jamison CEO,
Scalable Display Technologies
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Example Case 50 COTS HD projectors on a 40 dome
Message Its all about the system solution
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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

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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
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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

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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
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Light/black levels

• First consider impact of screen shape/finish
• Part 60 4.d surface contrast ratio 51
• cross reflectance1 lux of ambient light (i.e. a
  small candle), the max perceivable contrast ratio
  is 5001. A dimly lighted room with 30 lux of
  lighting would squash the maximum perceivable
  contrast ratio to 501
• 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 numbersdid it say ANSI?
• Look for iris and iris controls
• Brightness
• 4.e - Not less than six (6) foot-lamberts (20
  cd/m2).

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Black level challenge
Edge-blended tiled example
High contrast ratio projectors are required for
good blends
Area of maximum shared light
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Color depth
10 Bit color through the entire pipeline makes
for brilliant displays
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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

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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

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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

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Texture Filtering Basics

• Better quality re-sampling better quality images

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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
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• One radian is the angle subtended at the center
  of a circle by an arc that is equal in length to
  the radius of the circle.
• 1 radian 57.3

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Graphic Cards Allow for Resolution Higher

• Multi-GPU technology (Vista only)
• nVidia's 'SLI'
• ATI's 'Crossfire
• Quad output cards
• Pixel shader abilities

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Its a system

• Points of failure are
• Cables
• Connectors
• Power supplies
• Simulators/FTD are controlled environments
• Know screens, IGs, projectors
• These are repeatable environments

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• 4 Projector Dome, 220 Degrees.

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• Thank you