POV-Ray : Newsgroups : povray.advanced-users : Tech Question: How does POV's focal_blur operate? Server Time
29 Jul 2024 12:17:52 EDT (-0400)
  Tech Question: How does POV's focal_blur operate? (Message 1 to 5 of 5)  
From: Glen Berry
Subject: Tech Question: How does POV's focal_blur operate?
Date: 22 May 2002 02:09:24
Message: <NTTrPFBQeOBEB9RfxAASf62AUwgd@4ax.com>
First, let me be specific. I'm not asking exactly how the source is
coded for this feature. I'm also not asking how to use this feature in
a POV-Ray scene file.

I want to know exactly how this feature functions, in a conceptual
sense. Does anyone know the exact details?



Later,
Glen

7no### [at] ezwvcom     (Remove the numeral "7")


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From: Jan Walzer
Subject: Re: Tech Question: How does POV's focal_blur operate?
Date: 22 May 2002 11:46:15
Message: <3cebbd47@news.povray.org>
simply put:
    assume that the focal point is the same as location+direction

when jittering now the location point, while having the focal point on the same place,
you get the nice fb-effect...


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From: Peter Popov
Subject: Re: Tech Question: How does POV's focal_blur operate?
Date: 23 May 2002 19:27:10
Message: <fbuqeu4jqlr4pgvg6f98ot73chaj9g7fuo@4ax.com>
On Wed, 22 May 2002 02:08:49 -0400, Glen Berry <7no### [at] ezwvcom>
wrote:

>I want to know exactly how this feature functions, in a conceptual
>sense. Does anyone know the exact details?

I thought it was explained in the docs but anyway...

Basically, instead of shooting a single ray per pixel, POV shoots a
bunch (that's way regular anti-aliasing is disabled when FB is used).
These rays are scattered more when getting farther from the focal
point. Statistical analysis (confidence and variance) is used to avoid
shooting unnecessary rays. The result is finally averaged.

That's pretty much about it. Hope it makes some sense (it might as
well not, it's 2:24 am here)


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg


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From: Glen Berry
Subject: Re: Tech Question: How does POV's focal_blur operate?
Date: 23 May 2002 23:54:43
Message: <4LftPE=pv4ZH21ulzSarO9aijiLB@4ax.com>
On Fri, 24 May 2002 02:24:38 +0300, Peter Popov <pet### [at] vipbg> wrote:

>Basically, instead of shooting a single ray per pixel, POV shoots a
>bunch (that's way regular anti-aliasing is disabled when FB is used).
>These rays are scattered more when getting farther from the focal
>point. Statistical analysis (confidence and variance) is used to avoid
>shooting unnecessary rays. The result is finally averaged.

Okay, that much I already knew, and the docs are good enough to
explain how to use the feature in a typical POV scene. However, I
could use a little more information for my current project. For the
particular details I'm wanting clarification or confirmation on, see
my next post in this news group, about 35mm Camera Emulation.



Later,
Glen

7no### [at] ezwvcom     (Remove the numeral "7")


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From: Slime
Subject: Re: Tech Question: How does POV's focal_blur operate?
Date: 24 May 2002 00:41:43
Message: <3cedc487@news.povray.org>
> Okay, that much I already knew, and the docs are good enough to
> explain how to use the feature in a typical POV scene. However, I
> could use a little more information for my current project. For the
> particular details I'm wanting clarification or confirmation on, see
> my next post in this news group, about 35mm Camera Emulation.


Your best bet might be to go into the source code and take a look at how
it's done. I looked at the source a long while ago, and if I remember right,
there's some sort of a "camera.h" (unless this part is within something like
"render.h" or something, i really forget) with an entire if block devoted to
if the focal blur is on.

 - Slime
[ http://www.slimeland.com/ ]


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