Re: Stereo Window and Convergence Examples

[P3D Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Mon, 23 Jun 97
>From: P3D  Gregg Podnar writes:
>
>..............................
>It may be appropriate to note that unlike retinal disparity, convergence is
>sensed from the eye muscle positions.  As this sensory mechanism is adaptive,
>when an unnatural convergence is required (i.e. setting the infinity point
>wider than interocular spacing), the muscles/nerves compensate.  This accounts
>for an inability to sense window distance when other cues (like the edges of 
>the screen) are not visible.
>				

**** Well described. It made me realize a part of why I consider convergence
to be a powerful cue. While you are viewing a stereo image, you can direct
your full attention to very small areas of the total scene. Doing so
provides a measure of the convergence of any specific point (eye muscle
comparisons). Checking both a close and distant point would define a
triangulated sense of space for the whole scene. 

If one were to pay attention to relative distances in the projection room
before everything was completely dark, you could establish in your mind a
comparative reference to be able to sense later in the dark,  how moving the
slide chips from side to side changes the projected depth of the total scene. 

I seldom look at a stereo image without testing the convergence of many
points in the scene. It's a quick and almost automatic scanning process.
That's why I consider it to be a strong effect. I use it all the time. I
find that doing so sensitizes one to smaller variations and this enhances
the overall depth effect by correlating with associated retinal disparities.
The two types of sensation reinforce each other.

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


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