Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!ucbcad!pasteur!ucbvax!ucsfcgl!pixar!flip
From: flip@pixar.UUCP (Flip Philips)
Newsgroups: comp.graphics
Subject: Re: Interactive Stereo Viewing
Message-ID: <1396@pixar.UUCP>
Date: 17 Jan 88 21:28:37 GMT
References: <4615@tut.cis.ohio-state.edu> <146@rocky8.rockefeller.edu>
Organization: Pixar -- Marin County, California
Lines: 45

In article <4615@tut.cis.ohio-state.edu> WAMBOLD@OSU-20 (Sandra Wambold) writes:
>
>Does anyone on this BB know the proper translations and rotations for
>interactive stereo viewing?  I am trying to program a Evans&Sutherland
>PS300 so people can use red-blue stereo glasses while they rotate a
>structure (real-time).  All I need to know is the correct angle for
>rotation and the required translation between the red and blue (or green)
>parts.  If anyone can tell I will be very happy, as I have been working
>on this problem for quite some time.
>
Transform the Left & Right views by these:

	1    0    0    0		1    0    0    0
	0    1    0    0		0    1    0    1
	0    0    0 -1/k		0    0    0 -1/k
	k/20 0    0    1    	       -k/20 0    0    0

	   Left Eye			   Right Eye

(This is directly from the book, the 0 in [4,4] for the right should be 1
if you are still maintaining normalized co-ords.)

Quote:
For a human with average eyesight the strongest stereo effect occurs at 50
cm in front of the eyes. Thus for  an eye seperation of 5cm, the stereo angle
is atan(5/50) or 5.71 degrees.
Endquote.

For the matrix above, k is the focal length & d is the distance between
your eyes, therefore atan(d/k) gives the stereo angle. From the above example
we see that the correct stereo angle is 5.71 deg. Therefore d = k/10 is
required to maintain the correct stereo angle. 

since you have d between your eyes each view requires d/2 = k/20. offset
each by + & - and you have a stereo pair. 

A more detailed explination can be found in _Mathematical Elements for
Computer Graphics_ by David Rogers and J.Allen Adams. 1976, McGraw Hill.
(You used to be able to pick it up in the Derby Book Store, it was a text
for CIS 781 or something like that)

Flip Phillips
Pixar
Marin County, Ca

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