Retinal rivalry in 3Discover images

[P3D <PTWW@xxxxxxx>]

Re: Gabriel notes problems fusing water around Statue of Liberty in the
3Discover Great America I cassette, image #2, but concludes the shots
were taken simultaneously.  I have to disagree.  Look closely at the
people walking on the path around the island, and especially at the
two people walking on the grass just to the right (as you look at it)
of the star point facing the camera.  The distance between those two
people is different in the right and left images, so at least one of
them was moving.  Also, the waves lapping up against the island are
different.  To me, this is more noticeable with the waves on the right
and left sides of the island, than with those in the front.  I don't know
whether Gabriel was referring to the breaking waves or the water generally,
but I think it is differences in the images that are causing the effect
he describes.

In contrast, image 3, (Golden Gate Bridge), which also has some
retinal rivalry, does appear to be taken simultaneously.  There are
about 5 very strong reflections in the right image that are not in the
left image; and at least one small reflection in the left image that
is not in the right image.  However, the cars on the bridge do not
appear to move and they fuse quite normally.  This image is not
labelled as an aerial view, however.

Image 7, (Chicago), is labelled aerial.  It has very little obvious
movement, but the steam rising from the red office building does
change between the two images.  #12, (New York) has slight movement;
some of it is in areas I can only see with one eye at a time anyway
when wearing glasses.

Of course, with aerial hyperstereo shots of cities, it is virtually
inevitable that there will be movement resulting in some retinal
rivalry.  It would take quite a large plane to get two cameras
spaced far enough apart!

The comments above are intended as documentary observations, not
criticism.  I think, however, the differences in the aerial shot of the
Pentagon are just annoying enough that, in a very tough call, I probably
would have voted on the side of shooting the scene over, or leaving it
off the cassette.

Paul Talbot


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