[net.movies] How does 3-D Work?

davy (03/10/83)

#N:pur-ee:7000029:000:822
pur-ee!davy    Mar  9 22:29:00 1983


	Last night I saw a double feature of two 3-D movies.  We won't
	discuss the technical merits of them, because there weren't any.
	I purposely went on dollar night, because I had never seen a 3-D
	movie before, and was curious.

	Now I'm thinking though:

		How do these 3-D movies work?  They give you a set
	of glasses, with one red and one blue lens.  So, I gather 
	that one eye gets one image, and the other eye gets another
	image.  The thing I don't get is:

		1. How does seeing two different copies of the same
		   image make it 3-D?  Are the images "next to each
		   other", or "one closer than the other", or what?

		2. How come when I took the glasses off, the movie 
		   was in color, but when I put them on, it was in
		   sort of black and white (except for yellows, etc.)?

--Dave Curry
pur-ee!davy

pvl (03/10/83)

I understand how the Red/Blue coding works, but while we're at it,
can anybody explain how the Polarized movies manage to get polarized
movies into standard theatres.  Are special projectors/filters used??
   Pete LaMaster BTL NJ (201)949-0040

jjm (03/10/83)

	3D movies attempt to recreate the method by which you normally
	see things.  That is, each eye gets a slightly different image,
	because it is looking at the object from a different position.

	This difference in viewing angle is referred to as inter-ocular
	parallax.  3D movies attempt to provide each eye with a different
	image, filmed from a pair of cameras (or other arrangement).

	The brain combines these two images, and voila!  3D.


	Two ways of doing this are A) color code two images and view
	through tinted lenses and B) polarize the two images and view
	through polarizing filters.

	Method A can be projected using a standard projector.  Method
	B requires a special projector (or pair of projectors) projecting
	through polarizers.


	Most available 3D films are trashy because of three problems:
		A) poor filming equipment lets the images get out
			of alignment
		B) poor projection equipment makes it worse
		C) most directors (and cameramen) have not taken the
			time to perfect the art of direction and
			filming in 3D.

	American Cinematographer magazine had a special issue recently about
	state-of-the-art 3D filming.  Special 70mm film is used, allowing
	the split images (each 35mm) to be recorded on the same frame.
	Special digitally controlled projectors are used to reduce "jitter"
	(a framing problem) when projected.  A special screen is used that
	does not de-polarize the light it reflects.  Disney World's new
	attraction "EPCOT Center" includes a special 3D theatre, showing 
	a specially produced film. Rumor has it that the effect is marvelous,
	using multi-speaker digital audio to enhance the effect.

	Jim McParland
	American Bell - Holmdel
	hou5e!jjm

bsw (03/11/83)

 	I kind o know basicly how 3D works with red/blue glasses,but 
	I won't (can't) explain it (because I really don't know that 
	much on it)(confusing,ain't it?). But, I have a pair o 3D glasses
	that work, but the lenses are both of black(kindof coalish color)
	Can anyone tell me how these work ?

		Ben Walls
		-cbosgd!bsw