Transcript Fulldome Display Specifications: A Proposal Fulldome Standards Summit Ed Lantz

Fulldome Display Specifications:
A Proposal
Fulldome Standards Summit
L’Hemispheric
CIUDAD DE LAS ARTES Y LAS CIENCIAS
Valencia, Spain
July 7-8, 2004
Ed Lantz
President
Visual Bandwidth, Inc.
[email protected]
Fulldome Systems
Single Projector
(Fisheye)
Multi-Projector
Edge-Blended
Edge-Blended Projection
Polar Source is
Split Into SubFrames and EdgeBlended
Sub Frame 1 Sub Frame 2 Sub Frame 3 Sub Frame 4
Many Projection Configurations
Five Projectors
Six Projectors
Seven Projectors
Plethora of Projector Technologies
•DLP - Digital Light Processor
•LCoS - Liquid Crystal on Silicon
•CRT - Cathode Ray Tube
•Scanned Laser
•GLV - Grating Light Valve
IPS Display Specification Standard:
Goals
•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
Brightness Measurements
Display
Parameter
IPS Light
Output
IPS Peak Light
Output
Measurement
Unit
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)
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 Average full-white brightness produced on 30(30/50 method) foot diameter dome screen with 50%
reflectivity.
footlamberts
(fL)
Display Brightness (fL) = Screen Reflectance * Light Output (lumens)/Screen Area (sq. ft.)
Brightness/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 Measurement
Color Uniformity
1931 CIE x,y Chromaticity Diagram
Courtesy LEDtronics, Inc.
Color Uniformity and delta E
MacAdam ellipses shown on the CIE 1931 (x,y)
chromaticity diagram at 10x magnification
[Wyszecki 1982]
Color 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.
Resolution
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
Resolution
50% MTF Requirement for Defining CRT Resolution
Contrast Ratio
Display
Parameter
IPS Contrast
IPS Sequential
Contrast
Measurement
Unit
Instantaneous contrast ratio of typical system
(not individual projectors) using IPS test
pattern.
N:1 (ratio)
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)
Color Gamut
Display
Parameter
Measurement
Unit
Color Gamut
CIE 1931 x, y values
numeric x,y
Frame Rate
Display
Parameter
Frame Rate
Measurement
Unit
Maximum, minimum and/or typical number of Frames/second
frames displayed per second, and whether the
(p, i)
frame rate is progressive or interlaced.
Gamma
Display
Parameter
Measurement
Unit
Gamma
(Your specification here)
(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
In Planning:
SIGGRAPH 2005
Fulldome Venue
Los Angeles Convention Center
Please review this spec and provide your
feedback for our proceedings!
Thank you.
Ed Lantz
President
Visual Bandwidth, Inc.
[email protected]