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From: SharkD
Subject: POV-Ray units of measurement
Date: 21 Jun 2007 04:00:02
Message: <web.467a2fc15f1b9d1296f3cfc0@news.povray.org>
What real-world measurements do POV-Ray units represent. Do to the way
interior media work, surely there must be a base-value of some sort.

-Mike


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From: Penelope20k
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 05:06:04
Message: <467a3f7c$1@news.povray.org>
After reading and re-reading, asking at re-asking the same question ..i dont
have found any information and answer about it .*

but after experience, i think that 1 units correspond to 1 centimer , (or a
inch )..
it seems that light absorbtion etc ..use 1 centimer unit ...







news:web.467a2fc15f1b9d1296f3cfc0@news.povray.org...
> What real-world measurements do POV-Ray units represent. Do to the way
> interior media work, surely there must be a base-value of some sort.
>
> -Mike
>
>


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From: Warp
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 05:10:39
Message: <467a408f@news.povray.org>
Penelope20k <pen### [at] caramailfr> wrote:
> but after experience, i think that 1 units correspond to 1 centimer , (or a
> inch )..
> it seems that light absorbtion etc ..use 1 centimer unit ...

  No, one unit corresponds to one unit, nothing else.

-- 
                                                          - Warp


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From: Penelope20k
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 07:21:37
Message: <467a5f41$1@news.povray.org>
at least if you use lightsys library ...





news:467a408f@news.povray.org...
> Penelope20k <pen### [at] caramailfr> wrote:
> > but after experience, i think that 1 units correspond to 1 centimer ,
(or a
> > inch )..
> > it seems that light absorbtion etc ..use 1 centimer unit ...
>
>   No, one unit corresponds to one unit, nothing else.
>
> -- 
>                                                           - Warp


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From: Christian Froeschlin
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 07:54:32
Message: <467a66f8$1@news.povray.org>
SharkD wrote:

> What real-world measurements do POV-Ray units represent. Do to the way
> interior media work, surely there must be a base-value of some sort.

Not really, because you can adjust the parameters for media and
other things arbitrarily, so there are no "physical constants" which
would allow you to derive the real-world scale even from the known
wavelength of the light. There might be some implicit assumptions
in some *default* parameters for this stuff, but I reckon they are
mostly "something which looks more or less reasonable".


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From: Rarius
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 11:02:30
Message: <467a9306$1@news.povray.org>
POVRay's units are just that... units. They bear no relationship to real 
world units what so ever. I regularly change what they mean between 
different scenes... If I am rendering a molecule, I might define that 1 unit 
is a nanometer. If I am rendering a spaceship I'll probably use 1 unit= 1 
meter... As an astronomer I often use 1 unit=1000Km...

Pick a scale that is appropriate for your scene... I'd suggest for scenes of 
the normal human scale, 1 unit = 1 metre is a good baseline.

Rarius

"SharkD" <nomail@nomail> wrote in message 
news:web.467a2fc15f1b9d1296f3cfc0@news.povray.org...
> What real-world measurements do POV-Ray units represent. Do to the way
> interior media work, surely there must be a base-value of some sort.
>
> -Mike
>
>


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From: Samuel Benge
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 15:18:01
Message: <467acee9@news.povray.org>
Warp wrote:
>   No, one unit corresponds to one unit, nothing else.
> 

That's true, but...

The camera has an angle. Is this a real-world setting? If so, what does 
one unit resemble most, considering a given camera angle? One inch, one 
centimeter, a foot, etc?

I usually don't worry about this, but it appears that some people do. 
There must be some answer which at least comes close.

~Sam


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From: Christian Froeschlin
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 16:16:57
Message: <467adcb9@news.povray.org>
Samuel Benge wrote:

> The camera has an angle. Is this a real-world setting? If so, what does 
> one unit resemble most, considering a given camera angle? One inch, one 
> centimeter, a foot, etc?

Sorry, I don't think the question makes sense. How would the camera
angle determine the unit? If you think of applying trigonometry, you
will find that the distance from the camera is expressed in the same
units, so it just cancels out in the ratios.


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From: Alain
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 19:33:14
Message: <467b0aba$1@news.povray.org>
SharkD nous apporta ses lumieres en ce 2007/06/21 03:58:
> What real-world measurements do POV-Ray units represent. Do to the way
> interior media work, surely there must be a base-value of some sort.
> 
> -Mike
> 
> 
POV units are purely arbitrary units. In a scene, one unit may be 1mm, while, in 
another one, it can be 100 miles...

-- 
Alain
-------------------------------------------------
I'm interested in the fact that the less secure a man is, the more likely he is 
to have extreme prejudice. (Clint Eastwood)


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From: Alain
Subject: Re: POV-Ray units of measurement
Date: 21 Jun 2007 19:39:11
Message: <467b0c1f@news.povray.org>
Samuel Benge nous apporta ses lumieres en ce 2007/06/21 15:18:
> Warp wrote:
>>   No, one unit corresponds to one unit, nothing else.
>>
> 
> That's true, but...
> 
> The camera has an angle. Is this a real-world setting? If so, what does 
> one unit resemble most, considering a given camera angle? One inch, one 
> centimeter, a foot, etc?
It depends at what distance you are from the camera. If the camera angle is 1 
radiant, then at 1 unit distance, you cover 1 unit whide, 10 unit away, you see 
10 units...
> 
> I usually don't worry about this, but it appears that some people do. 
> There must be some answer which at least comes close.
> 
> ~Sam
An angle in completely independant from the unit used. 1 degree is always 1 
dergee whatever mesurement system you use. 1 degree in imperial, american or 
metric is exactly the same.

-- 
Alain
-------------------------------------------------
At twenty years of age the will reigns; at thirty, the wit; and at forty, the 
judgment.
Benjamin Franklin


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