P3D Re: SIRDS/DIRDS/RDSs

[Jan Gjessing <jgjessin@xxxxxxxxx>]

Andrew Woods wrote:

>Hmmmm.  OK I got suckered in.  I should have said RDS where I said SIRDS.
>I was obviously too filled up with Christmas cheer to realise the error.

>The earliest reference I knew of to SIRDS was Bela Julesz's 1971 book
>"Foundations of Cyclopean Perception" (University of Chicago Press, Chicago).
>Presumably he had earlier papers which also referred to SIRDS.
>I have a faint recollection that Bela was the inventer of SIRDS but I
>could be wrong...
>
>Andrew Woods

Time for classification?
Stereo World July/august 1995 p 26, 27 and 28, had an article about the
proposed first RDS made by H.J. Mobbs made in 1919. This was also later
reprinted in the Journal of 3-D Imaging, January 1996 p10, 11.

It's about time to make a classification, because of, yes, random (not
always clear) names given. The growing diversity of different subgroups
makes it even more urgent to sort things out.

I propose that the origin could be described loosely as "Hidden Spatial
Impressions" (HSI) That means depth information which is only possible
to decode by stereopsis. As before mentioned many have experienced the
effect in supposed repeated regular everyday patterns. Handmade RDS took
a long time to surface. HSI will exclude ordinary stereograms as the
spatial nature often can be deducted from 2D to 3D by prior knowledge
and experience. However, there is no sharp borderline and it's possible
to fool the brain with an apparent 2D image and what it can be like in
stereo. "Ordinary" photographic stereo images can also be disguised and
only proper stereopsis at work can decode the image.   

To sort out confusion, any classification proposal today should be
accompanied by visual examples. RDS/SIRDS have also been called
autostereogram. Then, as earlier mentioned name like "random-dot
correlogram" pops up. The diversity now includes not only multiple
decoding modes(both hidden anaglyph and SIRD etc.), but also moving and
animated images at the same time.... 

What time? Well, check out this site and you will find an analogue
clock. Wait for some time(!), and it will start working. Classification?
HSI(yes)!  Animated(yes) But is it real-time?

http://www.pluto.dti.ne.jp/~rcn/Java/RDS/AnalogClock.html

jan gjessing


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