Re: spheric projection.

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Angus Dorbie (dorbie++at++sgi.com)
Tue, 30 Jun 1998 11:14:00 -0700

Huse wrote:
>
> Hi pfFolks,
>
> We would like to project the Onyx2 output (2 channels) on a spheric
> screen.
>
> It's necessarily to do any correction in Performer for avoid deformity
> in the screen?
>
> What about the case of two planes projection screens with 120 degress
> between them?
>
> What kind of correction may we do?
>

You need to apply distortion correction. Normally this is done by the
projectors. It's the kind of question that if you need to ask your
probably in trouble. A full understanding of this is a lengthy thing
to convey.

The key to solving this is choosing a design eyepoint w.r.t. the
display, and then sending video to the projectors which matches
the geometry of the area subtended by the projection resulting
from that the design eyepoint.

A test pattern is normally drawn which can be aligned to a
physical test pattern on the display surface and the appropriate
adjustment is then made to bring the virtual pattern in alignment
with the physical pattern. Either in the I.G. or the projectors.

Cheers,Angus.

-- 
"Only the mediocre are always at their best." -- Jean Giraudoux 


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