POV-Ray : Newsgroups : povray.pov4.discussion.general : Basic blur : Re: Basic blur Server Time
17 Sep 2021 23:53:40 EDT (-0400)
  Re: Basic blur  
From: Kenneth
Date: 22 Jan 2019 06:30:00
Message: <web.5c46fc62e22651a8cd98345b0@news.povray.org>
ingo <ing### [at] tagpovrayorg> wrote:

> You could try to greate a noise texture wit vey little ondulation, scale
> it down and use it as a normal for the camera,
>

and Clipka wrote:
> If you're just aiming to add some blur, the "camera normal" would indeed
> be the way to go...

Hey, that does work well:

camera{
......
......
normal{bumps 0.001 scale .0001}
}

Depending on the bump_size (the 0.001, vs. a larger value), the resulting image
*might* look a bit noisy-- but my own recourse would be to render the scene
with, say, 5 frames of an animation (no camera movement, but moving the bumps
pattern in  x via the clock, by some large random amount; then bring those
images back into POV-Ray and 'average' them together (using the'average'
pattern) and then re-photograph the result 1-to-1 for the *final* render. This
should help blend the noise.

Historically, when Hollywood used old-style rear-projection of scenes behind the
actors, the rear-projection screen was sometimes 'jiggled' when being
re-photographed, to 'smear' the inherent graininess of the screen(or to make the
graininess 'different' for each frame of the new photography.) Likewise in Ray
Harryhausen's stop-motion puppet-animation epics. It's the same principle here,
by averaging the POV renders.

Bald Eagle wrote:
> Things that come to mind are:
> a thin clear sheet or lens in between the scene and the camera,
> with an IOR > 1

I had earlier been toying with that idea as well. It works, but looks a bit TOO
grainy to my eyes. Plus, it has the effect of introducing more blur the farther
the scene's objects are from the sheet (kind of LIKE focal blur.) That was an
interesting surprise, but it makes sense.

(BTW, it was a bit difficult to find this 'normal' feature in the documentation,
as it's not under 'camera' in the in-built index, but rather
'perturbation/camera ray'. It's at "3.4.2.4 Camera Ray Perturbation" )


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