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Fulldome Standards Discussion

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  • Ryan Wyatt
    I have finally finished writing up my notes for the standards discussion held at the Western Alliance conference in Houston, Texas, on Saturday, 19 October
    Message 1 of 1 , Dec 13, 2002
      I have finally "finished" writing up my notes for the standards
      discussion held at the Western Alliance conference in Houston, Texas,
      on Saturday, 19 October 2002. I've been on the road the past few
      weeks, so quality time with my Zaurus (and without my laptop) has
      allowed for added focus on arranging these notes. Please feel free
      to expand on any of the ideas below -- and please correct any errors!

      A version of this document is available online at
      My original notes on the topic are still available at

      The meeting struck me as surprisingly useful. Those gathered
      discussed numerous issues surrounding the free flow of content
      between systems, and talk remained friendly and constructive
      throughout. Many thanks to Carolyn Sumners for scheduling the time
      and space for this meeting; further thanks to those who took the time
      to attend. I sincerely hope we can continue the good work started in

      Talk centered on three broad areas, with a few significant
      digressions. I've broken the following notes into four sections:
      Dome Originals, 3-D Environments, Control Protocol, and Action Items.
      I also added a final note on SIGGRAPH 2003, which would have
      foreshadowed what Ed Lantz posted here recently.

      The notes do not reflect the chronological structure of the
      discussion. Also, for some reason, I chose to write them in the
      present tense. Enjoy!

      Dome Originals

      Ryan Wyatt begins the discussion with a question about the prevalence
      of using Targas for image transport. Compressed Targas happen to be
      a tricky format for the American Museum of Natural History to support

      Aaron McEuen describes his experience using JPEGs as source material
      for the Digistar 3. With minimal compression, he was able to reduce
      disk space significantly without any noticable degredation in quality.

      Kevin Scott asks about difficulties in supporting multiple formats.
      Steve Savage warns against using formats that don't support alpha
      channels, noting that both Targas and TIFFs support alpha channels.
      Kevin Scott adds that the DDS format, prevalent among the DirectX and
      gaming communities, also supports alpha channels. Ed Lantz brings up
      HDR, a "loose" format with RGB floating point

      Ryan Wyatt makes the point that a few insipid elements could be
      incorporated into a dome original standard: using a black background
      for all non-drawn areas, for example, and keeping all dome originals
      square. Other items are possible, such as standardizing the
      orientation of the dome original in the image and agreeing on
      azimuthal versus celestial coordinates (i.e., making the zenith 0
      versus 90 degrees).

      Then Ryan Wyatt raises the issue of color space, and the discussion
      takes a turn toward the detailed.

      Ed Lantz describes difference in brightness moving between dome
      sizes. Imax defines minimum foot lamberts on the projection surface
      -- a minimum of 5 in front, 3 on side. If systems could be defined
      purely in terms of brightness, this would be a handy factor in
      defining post-processing techniques that could facilitate accurate
      translations between domes.

      Ed then suggests something along the lines of a "dome original
      reference frame," which could be bundled with every show.

      A dome original reference frame ("DORF") must take into account
      numerous factors, only a few of which are listed below. For example,
      it should allow for describing colors outside CRT color space (for
      laser projectors), which means "much more than bit depth." Steve
      Savage suggested that it could also clear up complicating details,
      such as determining the azimuth number on the horizon. The general
      idea of metadata is raised. How do we handle geometric compression
      for less than 180-degree dome -- or more than 180 degrees of rendered
      view angle? Ryan Wyatt notes that the Rose Center renders out a
      200-degree field of view from a design eyepoint that lies above the
      dome springline. How do we define a coordinate grid system? Do we
      include a forward point for tilted domes? Adopt a great circle
      format? This raises the issue of producing material outside the
      hemisphere. Aaron McEuen mentions a spherical image plug-in for
      Lightwave. Someone (I didn't note who) claims that it's more
      efficient to save a hemicube than polar dome masters.

      3-D Environments

      The question here relates to how different sites can share 3-D models
      and other information about the environments used to create either
      real-time spaces or playback sequences.

      Ed Lantz brings up the success the gaming industry has had with
      integrating development of hardware-based games and PC games. Aram
      Friedman mentions CAVE libraries as a common environment used by
      places such as the National Center for Supercomputing Applications

      One issue that may cause concern is the use of OpenGL versus DirectX:
      both are used by different systems, and interoperability may prove

      Kevin Scott wonders aloud if we've ever managed to translate between
      existing automation systems. Which leads us to...

      Control Protocol

      This topic arose on the fulldome list some time ago, when Kris McCall
      raised the question of whether virtual planets could be co-registered
      with an analog star machine.

      Steve Savage suggests that each company provide SDKs (Software
      Development Kits) to communicate between systems: this can apply to
      the virtual spaces in real-time systems as well as communication
      between virtual environments and, say, opto-mechanical star
      projectors. Savage notes that Sky-Skan and E&S used the method
      successfully to integrate the sun-moon projectors with Digistar 2.
      One benefit is that the possibly-proprietary image processors (IPs)
      of individual systems remain untouched.

      Someone raised the issue of platform dependence -- different vendors
      use different software platforms, although Windows prevails at the
      moment. Someone else asked who drives whom, in this case, to which
      Savage replied that the SDKs could be developed in two phases:
      first, reporting information from the star projector, so the virtual
      environment could tag along, then perhaps later allowing for commands
      going the other way.

      Any SDK should also include placeholders for undefined, special stuff.

      Action Items

      A Fulldome Technical Committee, with representatives of various
      vendors, should be formed to address some of the issues raised above.
      Jack Dunn and Ryan Wyatt agreed that the International Planetarium
      Society (IPS) should formally request that its member vendors take
      part in this committee.

      The International Commission on Illumination (CIE,
      http://members.eunet.at/cie) and Society of Motion-Picture and
      Television Engineers (SMPTE, http://www.smpte.org) have developed
      standards that could be used as a blueprint. Mark Javis brings up
      the work of the Inter-Society Color Council (ISCC,
      http://www.iscc.org), which could also provide some useful context.

      Results could be posted to the IPS website or fulldome site -- or
      both. The committee could also present ideas at the 2004 IPS Meeting
      in Valencia.

      SIGGRAPH 2003

      After the main agenda, such as it was, has been addressed, Ed Lantz
      calls for help with SIGGRAPH 2003, to be held in San Diego,
      California. There is a possibility of offering a full-day course at
      the Ruben H. Fleet Theater (where they will be celebrating the 30th
      anniversary of Omnimax, a.k.a. Domed Imax, next year).
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