Re: Computer Compositing

[T3D John W Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>> With today's tools you could put those images
>>into your computer and *fix* the parallax problem in the images themselves
>>then reconvert to film. This would be a much more ideal solution if the
>>problem is severe enough and worth being fixed. 

>Have you actually tried it?  The image is scanned into a perfectly planar
>bitmap and "objects" as such do not exist.  With a great deal of effort you
>can mask outline an object and cut it to its own layer, but then you must
>re-create what was hiding behind the object, sometimes you can borrow
>(clone) from the other image.  

I think the post to which you replied may refer to the recent P3D discussion
on creating a true 3D computer model, but deriving the information for the
model from *multiple* actual photographs.

>If you START with a computer generated image, where every object is either
>coded on a layer, or as an object, or exists in virtual space (ie,
>raytracing), then it is easy to adjust the various parameters of parallax
>and perspective.

I don't know how many photographs would be required for the "general case"
(if there is one) - I would guess it may take a minimum of 3 photographs
for motion along one axis, and more photos would produce better results.
There may be restrictions on specular reflections in the scene, or there may
even be a way to figure out and map reflection characteristics on surfaces.
(That last item seems a little farfetched on first glance, without lots of
human intervention.)

John R


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