How do they do that??

4 replies [Last post]
ChrisBitz
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Joined: Jun 8 1999

I've seen a new technique recently that I'm very curious about....

There are people moving about and all of a sudden they all freeze... a presenter walks about the frozen statues, and we notice that the statues are actually 3-D! as the camera is moving....

Probably not a good description, but hopefully someone will know what the hell i'm on about!! Sting used it in one of his videos about 6 months ago, and there's a holiday advert on at the moment (UK) with a load of people at a swimming pool.

I really can't think how it's done as you would have to take about 100 stills all at the same time for 4 seconds of frozen 3D footage.

Maybe thats how they do it.... or maybe with mirrors?

Chris.

andy_winton
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Joined: Jul 6 1999

Hi,

I'm sure this has already been explained
before on this group somewhere, but...

It's called 'slo-mo' or something like that.

They get some cameras in an arc, then at
one instant in time they take the frame from
each camera. They can then WARP (or Morph)
the inbetween frames. I think you can (for
video) get away with as few as 4 video
cameras per 90 degrees.

For 'The Matrix', they used about 90 35mm
still cameras linked together by computer.
The computer could then either take a shot
in one instance, or cascade thus giving very
slight movement.

The advert you saw probably used one of these
techniques with blue screen, so the non
affected character could move arround the
frozen ones.

Maybe someday I'll have more than 1 camera
to try all this fun!

Hope this helps,

andy

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--
Andy Winton
(see my Video at idlechild.net)

Alan Roberts at work
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Joined: May 6 1999

The system that's been used on tv a few times has an array of about 90 35mm cameras mounted in an arc of about 120 degrees. They are all fired in sequence. The result is a set of images from 90 odd view points. The tv signal is simply made by taking each frame in turn, no need for morphing. A sequence of 100 such cameras would make enough images for 4 seconds of video. The "live" presenter is added using chroma-key (colour separation overlay, blue screen, call it what you will) in the usual way.

Christian Lett
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Joined: Apr 26 1999

It's called Time Slice (or, in the case of The Matrix, Flo-mo). On the TV series, Supernatural, They used an arc-like device with a long strip of film inside. There were a set of lenses every inch-or-so which were fired at the same time. A 16mm camera (I think) formed the lens at the start so that the arcing snapshot would begin seamlessly from normal moving footage.

No post-production morphing was used there but on The Matrix, they used a bunch of still cameras (looked like Nikon F4 or 5s) so the distance between lenses was much greater than that on the Time Slice camera. Because the sequence needed to be nice and smooth, a special morphing technique was used to interpolate between each frame to produce the missing information. All these shots were done against a huge green screen so that digitally erasing cables (and the other cameras!) would be nice and simple. Apparently, all backgrounds for these shots were CGI...

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Christian J. Lett
[email=clett@nationalexpress.co.uk]clett@nationalexpress.co.uk[/email]

Christian Lett After Effects and Maya Artist www.quarterlightpictures.com

Eoin
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Joined: Jun 8 1999

Christian is spot on with this one only the system uses really crappy plastic lenses, the same ones which are used to make those disposable cameras so you'll quite often see a lot of distortion on the older time-slice cameras. Newer ones use slightly better lenses. If you are endowed with a modicum of technical savvy you'll be able to make one, but it'll probably take ages.

Eoin