P3D Re: DVD Private Eye

["Greg Wageman" <gjw@xxxxxxxxxx>]

From: Dottle <markaren@xxxxxxxxx>


>This is a dolly motion. Carefully choosing 2 frames from the movie (
>with an estimated parallax that resembles 2-3 inch lens spacing) If the
>background lacks depth in stereo, then the background scenes were added
>with a green screen or some other post-camera effect. If the background
>shows depth in stereo, then the set was of real construction, either a
>model or an actual location. Get it? I noticed some dolly scenes from
>the movie " The Haunting" are flat in stereo........so I conclude that
>these interior scenes are computer generated and the camera motion adds
>to the illusion of depth.
> Some backdrops from the movie " Starship Troopers" are in stereo!
These
>places do not exist so I conclude that models were used.


I don't necessarily agree with your conclusions, Mark.  As we all know,
stereopsis is created by horizontal disparity.  It doesn't matter
whether the objects are "real" or merely drawings.  A savvy cartoonist
knows that foreground objects move a greater apparent distance than
background ones during a horizontal trucking shot, and if drawn that
way, a stereo pair made from a cartoon "dolly shot" will show flat
objects at apparently different depth planes.  Likewise, a background
added using a two-dimensional screen (whether blue, green or
rear-projection) can still show depth if the proper disparity is present
between frames.

Perhaps the background plate was a "traveling matte" shot (i.e. a truly
2-D painting being physically moved behind the [stationary] car in
question).  A greenscreen of a true dolly shot would retain any
horizontal disparities originally present.

I haven't seen the shot you're talking about, but if they've somehow
'blown' the non-stereoscopic perspective depth cues, I can't imagine the
scene looking "right" even in 2-D.  It would look like a piano roll
scrolling by in the distance, or like the background behind Fred
Flintstone when he's driving his car through Bedrock.

     -Greg W. (gjw@xxxxxxxxxx)