Re: Vertical misalignment

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

Dr. T writes:

>> John B writes:

>> Sure you have vertical misalignment, or more properly vertical parallax,
>> _within_ the chips if you tilt the camera.

> What is the definition of misalignment or vertical parallax _within_ 
> the chips?  It is confusing to call "misalignment" something that is 
> subjective or requires a frame of reference to be observed.

We do have a frame of reference and it is the bubble level/inner ear.
The bubble level is on your Kodak and the inner ear is in your head.
The one mimics the other.  You normally will hold your head erect.  So
the camera should normally be level when it takes a picture.  However,
as you say, there are plenty of situations where you wouldn't keep the
camera level, including looking straight up or straight down.  None of 
these situations causes misalignment of the gates and lenses or mask
apertures and chips 8-) as I was attempting to say.  

I think the real confusion here is due to having an insufficient number
of terms to describe the situation.  That's why I tried to introduce
"vertical parallax" in place of "vertical misalignment" when talking
about camera tilt.  Vertical parallax means there is some parallax in
the vertical direction which is perpendicular to the horizontal 
direction which is established by the bubble level when you're taking 
the picture.  However, you won't see vertical parallax in the viewer 
reference frame, as I attempted to indicate previously, until you twist 
your chips which trigonometrically converts some of the camera's parallax 
from horizontal to vertical and from vertical to horizontal (in the 
viewer reference frame).  If there is too much of this, problems can 
arise.

> Finally if the person viewing
> the stereo image insists in tiling his head, then that's his problem.

I'm not sure what you mean by this.  Sounds like antagonism but knowing
you I'm sure it's not!  Most people viewing a scene taken with a camera 
tilted 45 degrees will find it more realistic if they also tilt their heads
when viewing 45 degrees in the same direction, whether left, right, up, 
or down.  Now, I'm talking about uncorrupted people here.  Old stereo hands
have become inured to everything imaginable!  8-)

In conclusion, I sure don't see where we disagree except as to terminology.

John B


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