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9Re: [fulldome] Some initial Full-Dome video thoughts

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  • Ryan Wyatt
    Oct 2, 2000
      In response to Don Davis's suggestion to remove star projectors from
      the optimal seating area in the planetarium, J. Scott Miller wrote:

      >So, what you are saying is that rather than reproduce a star field that shows
      >the subtle but vivid colors that stars show in the real sky, one should simply
      >settle for a mediocre star field, a star field where stars look like small
      >snowballs instead of points of light.

      As a proud owner of a snowball projector (a.k.a. Digistar), I find
      the trade-off perfectly acceptable: at least in terms of being able
      to put real-time 3D wireframe imagery on the dome. I can show a
      school group a model of the solar system (demonstrating clearly that
      the orbits lie in essentially the same plane), fly them around a 3D
      starfield, guide them through a cartoon of the Milky Way...

      What we show our visitors is *always* a caricature of the night sky.
      Even the much-vaunted Zeiss Mark 9.14159265 or whatever doesn't
      present a truly realistic image of the sky... The pinpoint stars
      look ab fab, but they stand out in too-high contrast against the
      background: it's not the real sky, and we shouldn't kid ourselves
      into thinking that way. (I'm not saying anyone on the list said
      that, BTW, but many of our colleagues seem to think that way.)

      That said, I haven't seen an acceptable starfield projected by
      full-dome video systems (I do have *some* standards, after all), with
      the possible exception of the Digital Galaxy at the Hayden.

      >A better solution would be to keep the star ball but put it on an elevator.
      >Remove it when it isn't necessary for programs in which astronomy is not the
      >purpose, or even during programs of an astronomy nature in which the stars are
      >acting like background anyway.

      That still doesn't address the fact that the star projector takes up
      the Best Seat in the House. When I visited the Hayden this past
      June, I had the chance, during a late-night session, to sit (well,
      actually, I laid flat on my back) in the center of the theater with
      the starball sunken and the SGI system rolling. Magnificent! That's
      where we need to be... Someday. Although I'm not sure when that day
      will come, it will come soon.

      As long as a system possesses real-time capability, it can perform
      the critical tasks to do a star show (my litmus test). But if you
      had to pre-animate star shows for a full-dome playback system, you'd
      never get anything else done.

      Denver will take the plunge with the first pitless planetarium. We
      can all see how well they sink or swim. :) I think the choice of
      laser video projection makes the most sense for reproducing a
      starfield, and their system will also work in real time. The best
      combination of choices for a planetarium application, IMO.

      Don wrote:

      >> In old Planetarium designs the audiences were asked to accept the cove
      >> line as a horizon, despite the resulting perspective of being in a shallow
      >> pit. A tilted dome gives the viewer a chance to see an eye level horizon,
      >> providing a more natural visual experience. The theme park rides I know of
      >> using dome projection are generally highly tilted, so audiences look
      >> forward as much as up.

      To which Scott (may I call you Scott?) replied:

      >I been in both and from my own experience, each has advantages in its own use.
      >But there are probably few audiences that want to feel like they are looking
      >forward when they have come to see the stars. A slight tilt is fine (ours
      >will be about 12 to 15 degrees) but I am glad we didn't opt for a dome tilt
      >more than that.

      I came on board at LodeStar after the theater design had been
      completed, and I initially dreaded working in the 25-degree tilt. I
      was particularly concerned about how the audience would adapt to the
      skewed horizon when doing a star show. My anecdotal perspective, six
      months down the line and 25,000 visitors later: dome tilt, no
      problem! I wouldn't do more than 30 degrees, but I'm quite happy
      with what I have to work with.

      And the full-dome video sequences definitely work better with the
      tilt. The only exceptions are the sequences that present a horizon
      parallel to the cove-line: then the audience feels like they're
      sunken into a bowl. But tilting the horizon in the animation (even
      less than the dome tilt) seems to remedy the problem.

      >> Although useful as an aquisition medium, the days of film being used in
      >> Planetarium projection are passing. I once had high hopes for Omnimax, but
      >> the medium was too ungainly and expensive for general use. The better
      >> efforts using fisheye film technology should be scanned and shown in
      >> digital formats, they may well appear superior to the images projected on
      >> film, especially if transferred at 30 FPS.

      I've had to deal with a 70-mm film projector in our SimEx theater,
      and let me tell you, I've never been a bigger fan of digital
      projection! Film is far, far, far too *analog* for me. Our
      projector requires more coddling and maintenance than any piece of
      machinery deserves to demand from a human. Plus, film has its own
      problems of uneven illumination and jitter.

      >Sorry, facts are facts. You don't get the resolution in video projection that
      >you get in film. You can kid yourself into believing it, but when all is said
      >and done, there is no comparison.

      And the fact is that full-dome video resolutions are already
      approaching or exceeding Imax(tm) resolutions on the dome. And the
      situation will only improve. Even if there's "no comparison" now
      (which I would dispute), there will be in the very near future.

      Can you say "Zulip"? Rhymes with tulip and julep... And although
      the demonstration we saw at IPS this year showed a technology in its
      infancy, it also showed tremendous promise. Mentally scaling up to
      the sizes and resolutions required for full-dome presentation, I
      convinced myself that (assuming they can correct the black-level
      issues and attain the resolutions they say they can) the technology
      should work beautifully for full-dome applications in a Denver-like
      time frame of two years.

      The greatest challenge with all these technologies right now is the
      price (n.b. that my favored technologies in this message have been
      SGIs and laser video projectors). But those prices will come down,
      in much the fashion Don referred to in his posting...

      >> Now people can create images filling a dome using affordable home
      >> computers and animation software. The days of machine shops under
      >> Planetaria custom building projectors for each show are giving way to
      >> artists and animators, on site and contracted, using software like Electric
      >> Image, Lightwave, and the various Strata and 3D Studio incarnations to fill
      >> the dome with digital enviornments.


      >And all have their place. But none are replacement.

      Not yet, but...

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