Re: PHOTO-3D digest 2297 -Reply

[P3D Peter Davis <pd@xxxxxxxxxxxxx>]

> Hey Gang:
> 
> Here is an off the wall question for any of the
> experts out there: 
> 
> If you take a conventional stereo pair and
> switch the left and right eye views, you get
> pusedostereo as we all know. 
> 
> If you take a properly mounted pair and simply
> turn it upside down, you have essentially the
> same thing as you would have if you mounted
> the Left eye view on the right and right eye
> view on the left. When upside down, the left
> eye is looking at the right image and the right
> eye is looking at the left image. It appears
> upside down, but not in pusedostereo.
> 
> Correct? 

That's right.  Looking at a slide upside-down will NOT give you
pseudostereo.  Basically, the left eye sees behind the left edge fo
the foreground objects, and the right eye sees behind the right edge.
If you flip this upside-down, the symmetry is preserved, so you're
seeing a stereo view of an upside down scene.

> How come then, does the image appear just to
> be upside down but not in puesdostereo?

Imagine you take a stereo picture of two telephone poles, one behind the
other, with the horizon in the background.  Right-side up, it might
look like this: 

	     |			   |
	   | |			   | |
	___|_|___		___|_|___
	   | |			   | |
	   | |			   | |
	     |			   |

Try turning this upside-down and ... voila, it looks the same!

--------
                                    Peter Davis
                             http://world.std.com/~pd/

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