Path: utzoo!attcan!utgpu!watmath!iuvax!mailrus!tut.cis.ohio-state.edu!hydroplane.cis.ohio-state.edu!ray
From: ray@hydroplane.cis.ohio-state.edu (william c ray)
Newsgroups: comp.graphics
Subject: Re: synthetic -> hologram
Message-ID: <58487@tut.cis.ohio-state.edu>
Date: 24 Aug 89 14:15:21 GMT
References: <4791@portia.Stanford.EDU>
Reply-To: william c ray <ray@cis.ohio-state.edu>
Organization: Ohio State University Computer and Information Science
Lines: 32

In article <4791@portia.Stanford.EDU> rick@hanauma (Richard Ottolini) writes:
>
>Plate #22 in Upstill's RenderMan companions is the "shattered globe" image
>that recently appeared as a National Geographic cover hologram.
>Could someone explain how this synthetic image was converted into a hologram?
>Thanks.

Relatively 'easily'...

The technique is described rather clearly in 'Holography Handbook', by
Unterseher.  decent all around holography handbook for practical holography
from beginner to advanced level.

Anyway, the method is to render successive views of the object from different
directions,  (the same method was used for making the 'Leslie' hologram, if
anyone remembers her), and then using an cylindrical lens, the images are
projected onto vertical slats of the hologram film, (obviously along with a
reference beam, or else we'd just have black lines on the film), typically
in the range of .5-1mm wide.  Each frame/image is projected in this manner,
onto successive slats of the film.  Once finished, process as usual, and make
contacts, or whatever.

When viewing, the trick is that each eye sees a different hologram because
of the difference in the eye-image angle for right and left eyes.

(disclaimer... this is VERY basic, and not intended to be a recipe for do-it
yourself computer holograms...  
Do Not Try This At Home Children... This trick is being performed by TRAINED
professionals, and is VERY dangerous... etc etc etc)

hope that helps
Will Ray