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28 Nov 2024 08:35:49 EST (-0500)
  Transparent 'mist' (Message 1 to 8 of 8)  
From: Gavin
Subject: Transparent 'mist'
Date: 24 May 2007 09:25:02
Message: <web.465591f08831d8d748edb2090@news.povray.org>
Hi,

I'm trying to use povray to display some scientific data. I have the
concentration of a drug (as its released from a nanoparticle) as a function
of x,y and z coordinates. I was trying to display it as a kind of mist. I
originally tried to have lots of transparent boxes (for each grid point)
and make them absorb light depending on the concentration. However, I
seemed to be getting diffraction-like patterns emerging, presumably from
the edges of all the boxes stacked together (although I don't know how as
povray doesn't include diffraction). So I tried to use merge to collect all
the boxes together, but now povrays ground to a halt.

Am I trying to display this data in a really stupid way? Does anyone know a
better way of doing this?


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From: Stephen
Subject: Re: Transparent 'mist'
Date: 24 May 2007 09:45:02
Message: <web.4655967a6f4bc474c4e49fa40@news.povray.org>
"Gavin" <gav### [at] gmailcom> wrote:
> Hi,
>
> I'm trying to use povray to display some scientific data. I have the
> concentration of a drug (as its released from a nanoparticle) as a function
> of x,y and z coordinates. I was trying to display it as a kind of mist. I
> originally tried to have lots of transparent boxes (for each grid point)
> and make them absorb light depending on the concentration. However, I
> seemed to be getting diffraction-like patterns emerging, presumably from
> the edges of all the boxes stacked together (although I don't know how as
> povray doesn't include diffraction). So I tried to use merge to collect all
> the boxes together, but now povrays ground to a halt.
>
> Am I trying to display this data in a really stupid way? Does anyone know a
> better way of doing this?

I think that media and a df3 density file might be one of the ways you could
do this.

Section 3.5.11.11  Density_File


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From: Thorsten Froehlich
Subject: Re: Transparent 'mist'
Date: 24 May 2007 10:02:49
Message: <46559b09$1@news.povray.org>
Gavin wrote:
> However, I
> seemed to be getting diffraction-like patterns emerging, presumably from
> the edges of all the boxes stacked together (although I don't know how as
> povray doesn't include diffraction).

Are you sure you did not just exceed the max_trace_level?

	Thorsten


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From: Marc
Subject: Re: Transparent 'mist'
Date: 24 May 2007 11:17:08
Message: <4655ac74$1@news.povray.org>

web.465591f08831d8d748edb2090@news.povray.org...
> Hi,
>
> I'm trying to use povray to display some scientific data. I have the
> concentration of a drug (as its released from a nanoparticle) as a 
> function
> of x,y and z coordinates.

Why not an objet the shape and the size that fits to your function display 
(a box, a sphere...) with a material of that kind :



material{
   texture
         {
            pigment
            {
               color rgbt 1 // transparent object surface
            }
         }
         interior
         {
            media
            {
               emission rgb 1// any color you want
               density
               {
                  function{max(0,1-(x*x+y*y+z*z))} // your function as a 
density pattern here (the example is a spherical pattern)
               }
            }
         }
}



Marc


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From: Marc
Subject: Re: Transparent 'mist'
Date: 24 May 2007 12:13:25
Message: <4655b9a5@news.povray.org>

4655ac74$1@news.povray.org...
>
> Why not an objet the shape and the size that fits to your function display
an obect with the keyword 'hollow' of course

Marc


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From: Alain
Subject: Re: Transparent 'mist'
Date: 24 May 2007 18:36:01
Message: <46561351$1@news.povray.org>
Gavin nous apporta ses lumieres en ce 24 / 05 / 2007 09:24:
> Hi,
> 
> I'm trying to use povray to display some scientific data. I have the
> concentration of a drug (as its released from a nanoparticle) as a function
> of x,y and z coordinates. I was trying to display it as a kind of mist. I
> originally tried to have lots of transparent boxes (for each grid point)
> and make them absorb light depending on the concentration. However, I
> seemed to be getting diffraction-like patterns emerging, presumably from
> the edges of all the boxes stacked together (although I don't know how as
> povray doesn't include diffraction). So I tried to use merge to collect all
> the boxes together, but now povrays ground to a halt.
> 
> Am I trying to display this data in a really stupid way? Does anyone know a
> better way of doing this?
> 
> 
Have a box or sphere just large enough to completely contain your points.
Make it hollow to enable it to contain a media.
Add an interior{...} block and a media.
Use your function to modulate the dencity of that media.
Make the media emissive so that it's visible without an external light source.
	You could also use scatering media and have some light shine on your media.
Emissive media will render faster, scatering media is slower, but more realist 
and will cast shadows.
When using media, the default sampling method is 3, never increase intervals, 
increase samples. It's much faster, and increasing intervals can cause nasty 
artefacts.

-- 
Alain
-------------------------------------------------
I couldn't repair your brakes, so I made your horn louder.


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From: Gavin
Subject: Re: Transparent 'mist'
Date: 25 May 2007 05:05:01
Message: <web.4656a67f6f4bc47448edb2090@news.povray.org>
> I think that media and a df3 density file might be one of the ways you could
> do this.
>
> Section 3.5.11.11  Density_File

Thanks alot for everyones suggestions! The df3 ensity file sounds like a
really good way of doing it, and I've found this helpful website which says
how to create the df3 files....

http://local.wasp.uwa.edu.au/~pbourke/modelling_rendering/df3/

Thanks again!


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From: Marc
Subject: Re: Transparent 'mist'
Date: 25 May 2007 09:16:13
Message: <4656e19d@news.povray.org>

web.4656a67f6f4bc47448edb2090@news.povray.org...
>> I think that media and a df3 density file might be one of the ways you 
>> could
>> do this.
>>
>> Section 3.5.11.11  Density_File
>
> Thanks alot for everyones suggestions! The df3 ensity file sounds like a
> really good way of doing it, and I've found this helpful website which 
> says
> how to create the df3 files....
>
> http://local.wasp.uwa.edu.au/~pbourke/modelling_rendering/df3/
>
> Thanks again!

It looks like emitting media is what you need.
I keep thinking if you have a function describing the density, you may skip 
the df3 file step by implementing your function in SDL (Scene Description 
Language, the POV-Ray script language).
It is more versatile.

Marc


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