Re: View port vs. view plane camera (was Re: Quesa - "Most Wanted" list)

[James W. W. <os...@jw...>]

On Jun 4, 2004, at 11:36 AM, Edward K. Chew wrote:

> Now, I am assuming the only way to adjust the perspective effect is to 
> play with the field of view, so I think I need to stick to whatever 
> value I have calculated for it.

Not following you there.  How much "perspective effect" you see in the 
image of a particular object depends only on the distance between the 
camera and the object.  The field of view only determines how much 
stuff is visible.

>  On the other hand, I think there are several ways you can manipulate 
> the scale of the image.  Reducing the distance of the camera from the 
> view plane

If you mean, moving the view plane closer to the camera, yes, that 
would make a bigger image on the view plane.  But I'm not sure how 
that's relevant.

> or shrinking the size of the view port should both have a linear 
> dilation effect.

Hmm?  Shrinking the size of the view port just makes less of the image 
visible, exactly like reducing the field of view.

>  I suppose you could also do it at the geometry level with a scaling 
> transform.
>
> So if I understand these view ports correctly, I should be able to 
> compensate for changes in view port dimensions by changing something 
> else at the same time like the camera distance, and there should be no 
> distortion of the image in either size or perspective.  Correct?
>
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