POV-Ray : Newsgroups : povray.binaries.images : Help! (11Kb Attachment) Server Time
14 Aug 2024 15:15:45 EDT (-0400)
  Help! (11Kb Attachment) (Message 1 to 8 of 8)  
From: Aaron Gillies
Subject: Help! (11Kb Attachment)
Date: 21 Sep 2002 12:58:12
Message: <3d8ca524@news.povray.org>
Folks:

Help!

Why is the color of the sphere lighter under water than it is
above water?  Is there any way that I can fix this?

Aaron

Aaron Gillies
New York City
x3rxes[^]yahoo.com


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Attachments:
Download 'water.JPG' (11 KB)

Preview of image 'water.JPG'
water.JPG


 

From: Slime
Subject: Re: Help! (11Kb Attachment)
Date: 21 Sep 2002 13:54:06
Message: <3d8cb23e$1@news.povray.org>
Source perhaps?

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


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From: Aaron Gillies
Subject: Re: Help! (11Kb Attachment)
Date: 21 Sep 2002 14:09:43
Message: <3d8cb5e7$1@news.povray.org>
"Slime" <slm### [at] slimelandcom> wrote in message news:3d8cb23e$1@news.povray.org...
> Source perhaps?

It's nothing exotic ... just basic stuff:


camera {
  location <0, 0, -30>
  look_at <0, 0, 0>
  rotate <5, 0, 0>
  }

light_source {
  <-10000, 10000, -10000>
  rgb 2
  }

// Sky

background {
  color rgb <.25, .5, 1>
  }

// Water

plane {
  y, 0
  texture {
    pigment { color rgb 1 filter 1 }
    finish { reflection { 0, 1 } }
    normal { bozo 2 }
    }
  }

// Ocean Floor

plane {
  y, -1000
  texture { pigment { color rgb .25 } }
  }

// Sphere

sphere {
  0, 10
  texture { pigment { color rgb .5 } }
  }



Aaron

Aaron Gillies
New York City
x3rxes[*]yahoo.com


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From: Christoph Hormann
Subject: Re: Help! (11Kb Attachment)
Date: 21 Sep 2002 14:15:00
Message: <3D8CB723.44C8981@gmx.de>
Aaron Gillies wrote:
> 
> Why is the color of the sphere lighter under water than it is
> above water?  Is there any way that I can fix this?
> 

Adding 'conserve_energy' to your water finish probably helps.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______


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From: Aaron Gillies
Subject: Re: Help! (11Kb Attachment)
Date: 21 Sep 2002 14:17:39
Message: <3d8cb7c3$1@news.povray.org>
Erm, yes ...

That pretty much fixed it. :)

Thanks.

Aaron

Aaron Gillies
New York City
x3rxes[*]yahoo.com


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From: Slime
Subject: Re: Help! (11Kb Attachment)
Date: 21 Sep 2002 16:55:35
Message: <3d8cdcc7@news.povray.org>
> Adding 'conserve_energy' to your water finish probably helps.

Mathematically, what does this keyword do?

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


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From: Christoph Hormann
Subject: Re: Help! (11Kb Attachment)
Date: 21 Sep 2002 17:13:07
Message: <3D8CE0E3.26DCE9D7@gmx.de>
Slime wrote:
> 
> > Adding 'conserve_energy' to your water finish probably helps.
> 
> Mathematically, what does this keyword do?
> 



Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______


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From: Slime
Subject: Re: Help! (11Kb Attachment)
Date: 21 Sep 2002 20:00:00
Message: <3d8d0800$1@news.povray.org>
> See Docs: '6.7.3.5 Conserve Energy for Reflection'

It says...

"When conserve_energy is enabled, POV-Ray will multiply the amount filtered
and transmitted by what is left over from reflection (for example, if
reflection is 80%, filter/transmit will be multiplied by 20%)."

So what does it mean when "reflection is 80%"? When does that occur? Is it
talking about "when variable reflection causes only 80% of the maximum
reflection to occur", or "when you use reflection .8", or "when the color of
the light reflected is <.8,.8,.8>?" Or what?

AFAIK, reflection can't be measured in percentages; it's merely the color of
the light coming from the reflected direction multiplied by some value, and
added onto the color of the object at that point. The color of the incoming
light could be any value from negative to positive infinity. I see no way to
represent that as a percentage.

So, basically, here's how I believe reflection and transmittance is normally
calculated:

color_of_object_at_point_a =
color_caused_by_pigment_of_object_and_light_sources_at_point_a
+
incoming_light_at_reflected_angle * reflection_amount_at_point_a
+
incoming_transmitted_light * transmission_amount_at_point_a

Am I right or wrong? If I'm right, how is this equation modified to take
conserve_energy into account?

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


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