Re: Headtracking with the screen (not HMD) as projection plane

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Nathaniel Bletter (nat++at++od.sri.com)
Tue, 15 Oct 1996 13:16:56 -0700

Your first method with off-axis projections is correct, you probably just have
some measurement wrong. To get this to work well, you have to have screen to
source, source to tracker, tracker to eye transformations, screen dimensions
and eye separation measured very accurately and in the same units. If any of
these are wrong, the object can looked warped with motion, but if they are all
correct, it will look great. What kind of tracker are you using? Is the tracker
coords to inches/meteres factor correct?

On Oct 15, 5:29pm, Daniela Rainer wrote:
> What is the best projection for headtracking (with a ultrasonic or magnetic
> tracker) with the workstation or other screen as projection plane?
>
> 1. Way
>
> Off axis projection (asymmetric frustum) with the frustum defined by a near
> plane parallel to the screen:
>
>
> .------------------------------. far
> . .
> . .
> ---------------------- screen
> . .
> . .
> . l r . l...left
> .------|---. near r...right
> . | .
> . | .
> .|.
> eye = tracker position
>
>
> The problem is, that objects are distorted.
>
> 2. Way:
>
> With an on axis projection (symmetric frustum) the objects look ok but if you
> move the head, it looks as they are moving.
>
>
> Thanks for any answers
> Regards
> Daniela
>
> --
> -------------------------------------------------------------------------
> Daniela Rainer | email: rainer++at++rus.uni-stuttgart.de
> Rechenzentrum Uni Stuttgart (RUS) | Tel: +49 (0) 711 685 5970
> Allmandring 30a, 70550 Stuttgart | Fax: +49 (0) 711 678 7672
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>-- End of excerpt from Daniela Rainer

--


Nat Bletter
SRI International
nat++at++od.sri.com
http://os.sri.com/people/nat/
(415) 859-4358
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