Stereo Split Sceen in O

Evans P.R. pre at al.mrc-lmb.cam.ac.uk
Mon Aug 15 02:51:30 EST 1994


In article <32gpkl$jj5 at columba.udac.uu.se> gerard at rigel.bmc.uu.se (Gerard Kleijwegt) writes:

   |> 
   |> The classic way of getting L/R stereo pairs for publication is to set up the
   |> picture you want, full screen, mono for the (eg) left image, take a
   |> picture,  then rotate the picture 6 degrees (or approx), and take a
   |> picture for the right image.  The reason for doing this is that you lose
   |> half the screen resolution in _all_ stereo modes (even on the ESV with its
   |> fantastic anti-aliasing).  Consequently, if you do it the way I suggest,
   |> the final printed images will be better, even though it means you have to
   |> fiddle & stick two half-images together.
   |> 
   |> Of course, in the good old PS390 FRODO 6.6 days, there was a toggle that
   |> switched between full-screen stereo, split stereo, left image and right
   |> image. That way, it was dead simple to do what I am describing. Isn't it
   |> amazing what advances in software & hardware can bring you?
   |> 
   |>                Adrian
   |> 
   |> -- 
   in the SGI version of O, this is controlled by the
   F-keys
   in *all* versions of O, however, you can use the
   Rotate_obj command:

     (make your picture; take a photo)
      O > rot_obj ;;
     (now you have the other one; take a photo)

   --gerard

Note that you should not really do stereo with a y rotation, but with a
shearing operation which changes the screen x but not z. If you use a
rotation, you get different bits clipped by front & back clipping planes
(slab) in the L & R eye view which confuses the eye. A suitable stereo
operation is

	( 1.0 0.0 +-0.05 ) ( x )
	( 0.0 1.0   0.0  ) ( y )
	( 0.0 0.0   1.0  ) ( z )

In O, stereo is correctly implemented on ESV, but wrongly on SGI

	Phil
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Smail:  Phil Evans
        MRC Laboratory of Molecular Biology, Hills Road,
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Email:  pre at mrc-lmb.cam.ac.uk
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--------------------------------------------------------------------------
Smail:  Phil Evans
        MRC Laboratory of Molecular Biology, Hills Road,
        Cambridge, CB2 2QH, UK
Phone: +44-(223)-402211   Fax: +44-(223)-213556
Email:  pre at mrc-lmb.cam.ac.uk
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