P3D Re: aligning in 2d vs 3d

[Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Sat, 6 Mar 1999 
>From: "Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
>......................
>OK, OK... I know what you are going to say Larry... You did
>not say that aligning images in 2D is impossible... you said
>it is comical.  

*****   ( and I do it too!   ;-)


>
>However, some people use alignment gauges or other 2D aids 
>because their eyes tolerate a lot of vertical misalignment.
>
>(Actually, I can make a strong case that vertical alignment
>can be only be corrected in 2D... even if you use both eyes,
>you are really alternating vision in R and L to see how the
>images intercept the fixed frame or reference lines.  It is
>only a sense of discomfort that indicates vertical misalignment
>during stereo viewing and you cannot rely on that sense.

*****  You're right, my comment does not apply to every adjustment. Some
things are hard to align except in 2D. The stereo window for example is not
one of those things.



>I am amused - i.e. find it comical! - when projectionists
>claim they can detect and correct misalignments during a stereo 
>projection *without* looking over their glasses... I think this
>is impossible.)

*****  I wouldn't think it's impossible, but it might require a lot of
projection experience as well as lots of comparing with and without glasses
under all conditions.


>
>Also, some people just cannot see the stereo window well 
>in 3d.  The vertical lines of an alignment gauge can help in 
>this case.

*****  Help, yes, but it's still a bit of gueswork. The final test of having
done it right usually is to view it in 3D. There are learnable skills
involved that make any tool easier and more accurate too.


>
>I will be reviewing the Stereo-Active Alignment Magnifier by
>J. van Ekeren, within the next few days.  This is a device
>that allows you to mount stereo slides while viewing them
>in stereo.  Very powerful tool for mounting stereo slides!


*****  Now that sounds like the right device! I look forward to this review.

Larry Berlin

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


------------------------------