Re: Fish eye correction with multi-channel

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Mark Baranowski (baranowski++at++marklynn.demon.co.uk)
Wed, 06 Nov 1996 15:13:37 GMT


On 06 Nov 96 05:35:32 EST, you wrote:
>I have to use a visual with a FOV of (80 by 60).
>To reduce the fish eye effect,I try to divide my screen by four channels.
>Each of them has a FOV of (40 by 30), the fish eye effect is reduce,
>but I have not a good continuity between the four channels.
>
<Snip>

>What do you think about this solution and the result : Is it a bug ?
>or is it a problem of approximation in the processing of the perspective ?

The problem with your edgematching may? be due to your use of four
rotated symmetrical viewing frustum. You can imagine that any plane
parallel to the near/far clipping plane in each channel approximates
(very roughly) to the surface of a sphere.
If you are displaying on a 'flat' display (e.g. a monitor) then
straight lines which cross channel boundaries will appear to have a
kink in them. Is this the effect you are seeing?

This effect can be eliminated on a flat display using assymetric
viewing volumes, but it will look exactly the same as your original
80x60 deg channel (I think!!) So unless the channels are on separate
pipes don't bother.

The image will only look correct if the relationship between your
physical eye and display device matches the software viewpoint and
viewing parameters.

Mark.

-- 
Mark Baranowski at work (baranowski++at++marklynn.demon.co.uk)
Pera, VR Division. Melton Mowbray, Leicestershire. UK.
Tel: +44 1664 501501, Fax: +44 1664 501553
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