Fulldome Display Specifications: A Proposal

Fulldome Display Specifications: A Proposal

Ed LantzEd LantzPresident

Visual Bandwidth, Inc.ed@visualbandwidth.com

Fulldome Standards SummitL’Hemispheric

CIUDAD DE LAS ARTES Y LAS CIENCIASValencia, SpainJuly 7-8, 2004

Fulldome Standards SummitL’Hemispheric

CIUDAD DE LAS ARTES Y LAS CIENCIASValencia, SpainJuly 7-8, 2004

Fulldome SystemsFulldome Systems

Single Projector(Fisheye)

Single Projector(Fisheye)

Multi-Projector Edge-Blended

Multi-Projector Edge-Blended

Edge-Blended ProjectionEdge-Blended Projection

Polar Source is Split Into Sub-

Frames and Edge-Blended

Polar Source is Split Into Sub-

Frames and Edge-Blended

Sub Frame 1 Sub Frame 2 Sub Frame 3 Sub Frame 4Sub Frame 1 Sub Frame 2 Sub Frame 3 Sub Frame 4

Many Projection ConfigurationsMany Projection Configurations

Five Projectors Six Projectors Seven Projectors Five Projectors Six Projectors Seven Projectors

•DLP - Digital Light Processor

•LCoS - Liquid Crystal on Silicon

•CRT - Cathode Ray Tube

•Scanned Laser

•GLV - Grating Light Valve

Plethora of Projector TechnologiesPlethora of Projector Technologies

•First-cut specifications for displays only– Should expand to include image generator specs– Ultimate spec must be a collaborative effort

•Independent of screen diameter & reflectivity– Should be similar to shopping for video projector

•System level specifications– We’re interested in what would be measured on dome, not

individual projector performance

IPS Display Specification Standard: GoalsIPS Display Specification Standard: Goals

Brightness MeasurementsBrightness MeasurementsDisplay

ParameterMeasurement Unit

IPS Light Output

Full-white (over entire dome) luminous flux actually delivered to dome surface, accounting for projector masking, overlaps, blending, and color matching. Uses ANSI lumens technique.

lumens (l)

IPS Peak Light Output

Same as above, except the measurement is made with a small area of white (3-degree circle) rather than full-white which can drive CRT projectors into current limiting.

lumens (l)

IPS Brightness (30/50 method)

Average full-white brightness produced on 30-foot diameter dome screen with 50% reflectivity.

footlamberts(fL)

Display Brightness (fL) = Screen Reflectance * Light Output (lumens)/Screen Area (sq. ft.)

Brightness/Color Uniformity MeasurementsBrightness/Color Uniformity Measurements

Display Parameter

Measurement Unit

IPS Brightness Uniformity

Peak-to-peak variation in brightness across the entire display, with respect to the average brightness. Specification must hold for all three primary colors in addition to white.

percent (%)

IPS Blend Uniformity

Worst-case peak-to-peak variation of brightness measured at three points along a line perpendicularly intersecting the blend region (points measured at center of and on either side of blend region). Specification must hold for all three primary colors in addition to white.

percent (%)

Bpp (%) = (Bmax – Bmin)/Bavg * 100

Blend Uniformity MeasurementBlend Uniformity Measurement

Color UniformityColor Uniformity

1931 CIE x,y Chromaticity DiagramCourtesy LEDtronics, Inc.

Color Uniformity and delta EColor Uniformity and delta E

MacAdam ellipses shown on the CIE 1931 (x,y) chromaticity diagram at 10x magnification

[Wyszecki 1982]

Color Uniformity - conclusionColor Uniformity - conclusion

Do we want to ask our industry to purchase and utilize spectrophotometers? Perhaps not. For now we can be assured of

first-order color uniformity by requiring Color Uniformity and Blend Uniformity specifications to hold for all three primary colors in addition to white. This technique makes the assumption that the

RGB primaries on all projectors are well matched at the factory.

ResolutionResolution

Display Parameter

Measurement Unit

IPS Resolution Minimum number of pixels projected per degree of arc on the spherical surface, assuming a nominal angular projection (180-degree hemispheric projection for fulldome systems, as specified with alternate configurations). For non-digital displays a 50% MTF criterion is used.

pixels/degree

ResolutionResolution

50% MTF Requirement for Defining CRT Resolution

Contrast RatioContrast Ratio

Display Parameter

Measurement Unit

IPS Contrast Instantaneous contrast ratio of typical system (not individual projectors) using IPS test pattern.

N:1 (ratio)

IPS Sequential Contrast

Frame-sequential (full white/full black) contrast ratio of typical system (not individual projectors) using IPS test pattern.

N:1 (ratio)

Instantaneous Contrast (IPS Test Pattern)Instantaneous Contrast (IPS Test Pattern)

Color GamutColor Gamut

Display Parameter

Measurement Unit

Color Gamut CIE 1931 x, y values numeric x,y

Frame RateFrame Rate

Display Parameter

Measurement Unit

Frame Rate Maximum, minimum and/or typical number of frames displayed per second, and whether the frame rate is progressive or interlaced.

Frames/second(p, i)

GammaGamma

Display Parameter

Measurement Unit

Gamma (Your specification here) (Hmmm…)(Hmmm…)

References

[Wyszecki 1982] G. Wyszecki & W.S. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae, John Wiley & Sons, New York, 1982

[Halsted 1993] Charles P. Halsted, “Brightness, Luminance, and Confusion,” Society for Information Display, March 1993, http://www.crompton.com/wa3dsp/light/lumin.html

SIGGRAPH 2005  Fulldome Venue

SIGGRAPH 2005  Fulldome Venue

Los Angeles Convention Center

In Planning:In Planning:

Please review this spec and provide your feedback for our proceedings!

Thank you.

Please review this spec and provide your feedback for our proceedings!

Thank you.

Ed LantzEd LantzPresident

Visual Bandwidth, Inc.ed@visualbandwidth.com