[photo-3d] Re: Stereo Dissolve- problem?

[Abram Klooswyk <abram.klooswyk@xxxxxx>]

George Themelis wrote 22 Sep 2000:
> There was a comment in the MF list about someone
> getting sick during a stereo dissolve projection
(...)
> Personally, not only I don't have a problem with
> stereo dissolve but I also see it as a nice thing to have.

Ray Moxom  23 Sep 2000:
>(...) I do believe that one of the curses of 3D is that those 
>who practice it constantly have very flexible eyes that can 
>accommodate all sorts of mounting, excess separation and other 
>defects that can screw the eyeballs out of some newcomers. 
(...)

I agree with Ray. I remember that when I went to club stereo 
projection sessions, in the early years I always went home 
with headache, but now for quite some years not so anymore, 
although still slides with many errors (made by new members) 
are shown. Koo Ferwerda many years ago has studied mounting
errors in an PSA exhibition (a Stockton-on-Tees / Holland one)
which caused complaints by non-stereo acquainted people.
(This where shows without dissolve.)
Two years ago I have written on it in Tech-3D, see: 
http://www.pauck.de/archive/mailinglist/tech-3d/mhonarc/msg01290.html 

The classical mounting errors are bound to be more conspicuous 
in dissolve projection, but apart from that setting up
dissolve 
projection shows is a special skill.
It requires, among other qualities, careful judgment of which 
3-D structure is to dissolve in which other, and especially  
_where_ in 3-D viewing space.

For example, a dissolve from an attention attracting feature 
on the left below at 3 meter distance to another feature at 
the high right and at 6 meter might cause nausea in some 
people. A _movement_ like that resembles being on a ship in a 
storm. Handing out motion sickness pills before a dissolve 
stereo show could be a solution :-) (Personnaly, I also never 
need such pills at sea or in the air, but I believe that was 
already so before I got used to stereo projection.)

But Pat Whitehouse' shows were the superb examples of the 
right technique. A macro of -say- a round single flower 
centrally placed at a virtual distance of 3 meter, dissolving 
in a large garland of flowers, which has the same virtual 
place, size and distance as the single macro flower, will
not give a perception of a movement in space, so will be
more acceptable for sensitive stomachs.

Unexpected movements in 3-D viewing space should not
be used too often, I believe.

Abram Klooswyk