1. Fulldome Display Specifications: A Proposal Ed Lantz President Visual Bandwidth, Inc. ed@visualbandwidth.com Fulldome Standards Summit L’Hemispheric CIUDAD DE LAS ARTES Y LAS CIENCIAS Valencia, Spain July 7-8, 2004

2. Fulldome Systems Single Projector (Fisheye) Multi-Projector Edge-Blended

3. Edge-Blended Projection Polar Source is Split Into Sub- Frames and Edge- Blended Sub Frame 1 Sub Frame 2 Sub Frame 3 Sub Frame 4

4. Many Projection Configurations Five Projectors Six Projectors Seven Projectors

5. DLP - Digital Light Processor LCoS - Liquid Crystal on Silicon CRT - Cathode Ray Tube Scanned Laser GLV - Grating Light Valve Plethora of Projector Technologies

6. 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: Goals

7. Brightness Measurements Display Parameter MeasurementUnit 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.)

8. Brightness/Color Uniformity Measurements Display Parameter MeasurementUnit 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

9. Blend Uniformity Measurement

10. Color Uniformity 1931 CIE x,y Chromaticity Diagram Courtesy LEDtronics, Inc.

11. Color Uniformity and delta E MacAdam ellipses shown on the CIE 1931 (x,y) chromaticity diagram at 10x magnification [Wyszecki 1982]

12. 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.

13. Resolution Display Parameter MeasurementUnit IPS ResolutionMinimum 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

14. Resolution 50% MTF Requirement for Defining CRT Resolution

15. Contrast Ratio Display Parameter MeasurementUnit IPS ContrastInstantaneous 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)

16. Instantaneous Contrast (IPS Test Pattern)

17. Color Gamut Display Parameter MeasurementUnit Color GamutCIE 1931 x, y valuesnumeric x,y

18. Frame Rate Display Parameter MeasurementUnit Frame RateMaximum, minimum and/or typical number of frames displayed per second, and whether the frame rate is progressive or interlaced. Frames/second (p, i)

19. Gamma Display Parameter MeasurementUnit Gamma(Your specification here)(Hmmm…)

20. 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.htmlhttp://www.crompton.com/wa3dsp/light/lumin.html

21. SIGGRAPH 2005 Fulldome Venue Los Angeles Convention Center In Planning:

22. Please review this spec and provide your feedback for our proceedings! Thank you. Ed Lantz President Visual Bandwidth, Inc. ed@visualbandwidth.com