Re: Ortho and Hyperstereo

[P3D Sam Smith <3dhacker@xxxxxxxxxxxxx>]

John Ohrt wrote:

>A question from a newbie:
>
>Say the object your are trying to photograph has nothing of significance
>in the forground or background and these areas will be ignored by the
>viewer, but the object itself has features best displayed by 3d.
>
>Suppose the aparent viewing distance you wish is five feet but you can't
>get closer than 10 feet.  Can you just double the lens separation (ie.
>from 62mm to 124mm) to achieve the desired effect, or is there a whole
>lot more I have to know?
>

I'm not sure if you're asking if this situation will appear ortho, or just
asking if an increased depth will be apparent. As far as increased depth,
yes. Will the subject appear the same as if you were 5' away, no. 
 
I good example of this is looking down a row of posts on a picket fence. If
you stood 5' away from the first post, and looked at its relationship to one
20 feet down the row, it is obvious that the farther one appears a fraction
of the near one's size.  Now step back 20 feet and look at the same two
posts. The farther one is now a lot closer to the first one in size.
I know your example says that there is nothing of significance in the
foreground or background, but that doesn't matter. If there is enough depth
in a scene to perceive it, than there's enough to show the apparent
distortion of not being at the same vantage point.

I've got a shot of Queen Elizebeth inspecting rows of guards which I took
using a bracket rig and two 135mm lenses. The depth is great, but unless the
guards at the end are 15' tall, it's percieved as unnatural.

sam

The 3D Hacker
website: http://www.cadvision.com/3dhacker/index.htm


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