Re: PHOTO-3D digest 1263

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Ronald Beck wrote:

>I'm sorry, but I must disagree somewhat with the statements below 
>regarding movies "are 3D" because of the movement.  While movies have 
>great movement and you do get a "sense of depth", you're relying on 
>"learned" depth queues.  The greatest example of this is the New York City 
>set they have at the Disney studios in Orlando.  This is a flat painting 
>of a New York street corner and it "appears" as though two streets diverge 
>at the corner and go on for about 1/2 mile.  This is a painting on a flat 
>surface.  To the camera eye though, it appears as if you were really there!

Ah, but, if (as originally stated) the camera tracked left or right during
that shot, the lack of any real depth in the matte painting would be
immediately obvious, because the various objects at different apparent
depths would not alter their relative positions, "giving away" the effect.
A shot of a matte like that would almost certainly be taken with the camera
locked down.

Rather than countering it, your example actually supports the argument of
there being depth in movies due to camera motion, as does your subsequent
example with the box corner.  (The camera movement "gave away" the effect.)
Depth cues are depth cues.  Two frames of a tracking shot give exactly
the same parallax cues as stereography, they're just separated over time.

	-Greg


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