[photo-3d] "Wobble stereo", "one-eyed stereo", VISIDEP

[Abram Klooswyk <abram.klooswyk@xxxxxx>]

Threads on this list often are like a Geysir burst: unexpected 
start, quick rise and suddenly over. So was the thread on 
wobble stereo which lasted for hardly a week last June. 
Although (too?)late, I have done some additional reading and 
should like to present some details for future reference. 

On 15 Jun 2000 I wrote: "Images of two TV cameras were shown 
in rapid succession, but not so quick as a flickering, I guess 
some 5 frames per second. If memory serves there even was a 
patent application for it."
I could have found the answer in the Photo-3D archives.

Ray '3-D' Zone wrote on 30 Aug 1998 to the list (in part):
>>In 1982 a professor of media arts at the University of South 
Carolina named Porter McLaurin along with his colleague Edwin 
R. Jones, a physicist, showed videotape footage of their 
autostereoscopic TV process they called "Visidep" on ABC with 
a nationally syndicated television program named "That's 
Incredible." Despite several marketing attempts, no widespread 
commercial application of Visidep ever took place.  
It is yet another unique example of the attempt to find the 
"Holy Grail" of 3-D:  a simple and universal autostereoscopic 
system.<<

The quest for the Holy Grail assumes that it _exist_ :-).
Or is it more like the Alchemists' making of gold?

Further back there was a Photo-3D thread on "one-eyed stereo" 
and Visidep in 1996. Tony Alderson also has written on
Visidep.

The TV broadcast was on aug 10, 1982 on ABC en CNN. 
John Dennis (then already editor!) wrote on it in "Stereo 
World", March/April 1983.  "VISIDEP" stands for "Visual Image 
Depth Enhancement Process". 

A patent search (www.patents.ibm.com) resulted in: 
Edwin R Jones Jr., A Porter McLaurin en LeConte Cathey filed 
a patent application on July 16, 1981, issued on jan 31, 1984, 
United States Patent 4,429,328, "Three-dimensional display 
methods using vertically aligned points of origin." 
Full text at:
http://www.patents.ibm.com/details?&pn=US04429328__&s_all=1

Later two other related patents were issued: 4,528,587 on 
July 9, 1985 and 4,924,853 on May 15, 1990. 
The inventors also have written: "VISIDEP (TM): visual image 
depth enhancement by parallax induction", SPIE Vol 457 
Advances in Display Technology IV, 16-19, 1984.

>From the text of the first US patent, 4,429,328:
>>a method for producing a three-dimensional illusion of a 
subject is provided which comprises the step of sequentially 
displaying on a viewing surface images of the subject as 
viewed alternatively first from one point of origin and then, 
time displaced, from another point of origin at a rate within 
a range of 4 to 30 changes between points of origin per 
second, with the points of origin being vertically displaced 
from one another. Preferably the above-mentioned range is 
between 6 and 15 changes per second, and most perferably about 
8 changes per second. <<

So my guess "5 frames per second" was not far off.
This seems also some answer to Ron Beck (13 Jun 2000):
>I wonder if there's an "optimum" wobble speed.  Would a 
>faster wobble speed give better depth perception?  
>Would a slower speed negate the 3D appearance?

An obvious question for us stereoscopists is: What vertical
"stereo" base? The inventors wrote: 
"Most preferably, the points of origin are vertically aligned 
with respect to one another and the points of origin are 
displaced from another a distance less than the standard 65 mm 
interocular distance of human eyes. The points of origin are 
perferably displaced from one another at a distance on the 
order of 10 to 15 mm."

Video and TV where used for the demonstrations, but the 
patent description also says:
"A still further aspect of the invention contemplates a method 
using two slide projectors for producing three-dimensional 
illusions from slides. (...) alternately displaying the slides 
at a rate within a range of 4 to 30 changes per second between 
the first and second slides. Perferably the rate of change is 
between 6 and 15 changes per second, and most perferably about 
8 changes per second. It is also perferable that the first 
slide be displayed from a first projector and the second slide 
be displayed from a second projector, with the step of 
displaying being achieved by alternately activating light 
sources of the first and second projectors."
(BTW: 'perferable' and '-bly' is the original spelling.) 

Vertical alignment of two projectors is not so unusual for us, 
and "alternately activating light sources" can easily be done 
by covering the lenses alternately. In fact, you can see this 
very often being done _before_ stereo slide shows, when the 
projection is tested! I indeed often see the wobble effect on 
those occasions. Moreover, you can see a similar effect, but 
horizontal, when you cover your eyes alternately with your 
hand _during_ stereoslide projection. Many of us have done 
this to test _which_ image is out of focus :-).

Sergio Baldissara on 14 Jun 2000 referred to this "obsolete 3d 
standard for TV: VISIDEP!" , which he found on a site devoted 
to "Dead Media", however the link he quoted (to islandnet) 
also is dead... The active link is: 
http://www.wps.com/dead-media/notes/23/233.html 
Dead medium: VISIDEP 3-D Television.

The first VISIDEP patent expired in 1996: "Expired due to 
failure to pay maintenance fee". 
It was not the Holy Grail after all...

Abram Klooswyk