Fulldome Standards Discussion
- 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!
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.
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...
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.
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
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).