P3D Re: Pulfrich Effect

[Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Sun, 28 Dec 1997
>From: Ron Fredrickson writes:
>
>> >Pulfrich question: if you make a traditional 3D movie with polarized or LCS
>> >glasses (instead of Pulfrich glasses), but display one view much darker than
>> >the other one, does the Pulfrich effect still work? It seems to me it would,
>> >but it would be interesting to hear whether it's actually been tried. 
>> >John R
>
> (Stuart asks: ) Could one simply increase the density of one polarizing
lens to 
>test this hypothesis?

***** If you mean the projection lens, that should work as long as the added
density is neutral to the polarizing factor. It doesn't seem that increased
density by partial cross polarization would be appropriate since it may
adversely affect the strength of the polarization itself.

A potential projection problem is whether a dimmer image on one side, even
though fully polarized, might end up with ghosting from the brighter side,
and thus ruin the effect. Worth trying though.


>>From Ron Fredrickson
>A friend recently lent me an Alaskan travelogue videotape which was
>advertised as 3-D with glasses included. This was a train trip on the White
>Pass and Yukon Railroad with much lateral motion portrayed. On this
>particular occasion I was using a pair of Pulfrich glasses with a very dark
>lens in place. To my surprise, I had the distinct impression that everything
>was in hyperstereo! Has anyone else noticed whether or not the degree of
>darkness of the viewing lens can change the depth perception in this way? 

*****  Yes, the effect is somewhat proportional to the degree of darkness.
There is probably an ideal range. Too light and there wouldn't be much depth
at all, and too dark one might not be able to experience any synthesizing of
two images at all. Kind of like looking through only one eye.

Larry Berlin

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


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