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a very special fulldome test at the Amsterdam Planetarium

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  • Michel Hommel
    A very special test Last month the Artis Planetarium in Amsterdam was the scene of a very interesting fulldome test. First the facts about our dome: we have a
    Message 1 of 1 , Mar 4, 2003

      A very special test

      Last month the Artis Planetarium in Amsterdam was the scene of a very interesting fulldome test. First the facts about our dome: we have a 20 meter dome with combines state-of-the-art slide projection (using 80 projectors divided over 31 projection planes) with 2 small dlp-beams, several special effect projectors, and - most importantly - a classical Zeiss projector, mark 4B, which is placed on an elevator inside a 6 meter deep central pit. Two years ago, when Sky-Skan modernized our infrastructure, our technician Mark Spoelstra, who invented Digidome together with Govert Schilling, came up with an interesting alternative to the existing fulldome video configurations.

      The simple concept comes down to this: instead of the classical arrangement of six huge videobeams (Barco 909) around the cove, place 18 smaller (and much cheaper) Barco 708 beams around the pit (beaming across the pit). In this position the beams don’t have to bridge 20 meters anymore, but only about 12 meters. As you will understand, we didn’t have 18 beams available to try this out. But thanks to Sky-Skan and our friends from the planetarium of Kiel in Germany last month we could do the test with six beams, covering more than one third of the dome with rendered material in SkyVision.

      The result was a very clear image, with a very high resolution. The highest resolution indeed, as far as I know, ever achieved with videobeams in a dome. And the light and the colours were just fabulous, ultra bright, approaching film quality. This result alone was enough in itself to call the test a success. But there was more to it. For the first time we could make a direct comparison between our Zeiss and the digital stars of Sky-Skan’s DigitalSky. The Zeiss’s stars still remained, in general, the better ones. But the digital stars have clearly crossed the line between ‘well at least it’s a start’ and being really acceptable for a Planetarium. Indeed they were so bright and crisp that it was often difficult to tell the difference between the Zeiss and DigitalSky. The digital Pleïades, for instance, looked awesomely good.

      I was amazed by what I saw in Wichita during the IPS-conference, I was stunned by what I saw in Jena at the ADLIP-demonstration, but I was really knocked off my feet by this little test in our own planetarium. Such an easy way to get a better picture!

      Of course this set up can’t be used for all planetariums. You need a central pit and the space to put 18 projectors in it (or 24 if you beam outwards from the pit, we didn’t try that but that would even improve on the quality). And then there is the issue of the star projector in the centre of our universe – can it stay in place, can it be combined with fulldome video? And if you worry about the costs: these 18 smaller projectors are a lot cheaper than the six big guys. Tweaking remains an issue of course, but the image every beam projects is a lot smaller, only one-eighteenth instead of one-sixth of the dome, so the effect of being out of line doesn’t get so bad. And in our dome we are already used to outlining 80 slideprojectors on 31 projection planes, so it can only get better.

      This set-up looks very promising, at least for our dome. I’ve just seen our fulldome future get a lot closer.

      Michel Hommel

      Artis Planetarium, Amsterdam

      The Netherlands

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