Kenneth nous apporta ses lumieres en ce 2007/09/20 02:38:
> This is something I posted recently, just as a comment at another,
> somewhat-related news thread; but I had been wanting to suggest it for some
> time, so  I thought I'd give it its own post...
> 
> I believe that an alternate
> type of focal blur would be visually/aesthetically useful, one that blurs
> the image only from the camera to the
> object/point of interest, then keeps the distance beyond that sharp. I'm
> thinking along the lines of "hyperfocal distance" in a real camera lens,
> but more extreme. It probably has no analog in the real world of lenses, but
> I believe (and this is subjective, of course) that it
> would help to make the blurring more realistic in some circumstances-- as
> for outdoor scenes on a
> bright and sunny day.  The blurring that POV currently uses sometimes makes
> objects in a scene look "small" or miniaturized--a sharp zone surrounded by
> a sea of blurriness.   I realize that real lenses do that (!), and that it's
> more pronounced when making close-up photos, depending on the lens aperture.
>  But I guess that's the point I'm trying to make: that the current focal
> blur has a tendency to make all scenes look like they are close-ups. But
> the way we "see" the world, things close to our eyes are blurry, things far
> away are sharp (or at least, our brains seem to make it so!)
> 
> I'm thinking that implementing such a blur in POV-Ray
> would *only* (?) require that image pixels (or rays) "beyond" the point of
> max
> sharpness not be jittered. As it is now, pixels/rays are jittered (equally?)
> in
> *both* directions relative to the max sharpness point.
> 
> Could this be implemented as easily as I imagine?
> 
> Ken W.
> 
> 
In to many scenes using focal blur, the aperture is set way to large, resulting 
in a "macro photo" type of rendering. It's good to show the focal blur, but give 
a miniature look.
If the camera to focal_point distanse is at least 100 times the aperture, you 
start  to remove that miniature look (medium close-up). A factor of about 1000 
or more is usualy realistic. With such a setting, the area of sharpness will 
extend farther from the focal point when moving away than moving toward the camera.
Think about it: with a real camera, your aperture can be mesured in milimeters, 
sometimes in centimeters, while your distances are normaly mesured in meters, 
even in kilometers. When doing macro photography, the aperture is still mesured 
in the same units, but the distances are in centimeters...

-- 
Alain
-------------------------------------------------
It doesn’t matter what you do. It only matters what you say you’ve done and what 
you’re going to do.

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