P3D Re: aligning in 2d vs 3d

["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.  

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.
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.)

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

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!

George Themelis


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