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31 Oct 2024 19:34:19 EDT (-0400)
  Display 3df data though a colormap on a isosurface from 3df (Message 1 to 6 of 6)  
From: mikaelk
Subject: Display 3df data though a colormap on a isosurface from 3df
Date: 14 Jan 2014 15:10:01
Message: <web.52d598e63148d87660cff8e80@news.povray.org>
Hello!

In short, I would like to visualize the electrostatic potential on an density
isosurface. Thus I have two 3df files, one for potential and one for density.

Similarly than in the figure in bottom of this page, except much more
beautifully.
http://www.cup.uni-muenchen.de/ch/compchem/pop/mep1.html

I know how to do the isosurface, but I can't figure out how to set a 'volumetric
texture' to it.

Best regards,
Mikael


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From: Alain
Subject: Re: Display 3df data though a colormap on a isosurface from 3df
Date: 14 Jan 2014 21:19:40
Message: <52d5f03c@news.povray.org>

> Hello!
>
> In short, I would like to visualize the electrostatic potential on an density
> isosurface. Thus I have two 3df files, one for potential and one for density.
>
> Similarly than in the figure in bottom of this page, except much more
> beautifully.
> http://www.cup.uni-muenchen.de/ch/compchem/pop/mep1.html
>
> I know how to do the isosurface, but I can't figure out how to set a 'volumetric
> texture' to it.
>
> Best regards,
> Mikael
>
>

A "volumetric" anything occupy a volume, not a surface.

A solution would be to make the isosurface transparent, add "hollow", 
and, finaly, add some media in the isosurface using your volumetric data 
from the dencity DF3.



Alain


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From: clipka
Subject: Re: Display 3df data though a colormap on a isosurface from 3df
Date: 15 Jan 2014 07:57:55
Message: <52d685d3$1@news.povray.org>
Am 14.01.2014 21:07, schrieb mikaelk:
> Hello!
>
> In short, I would like to visualize the electrostatic potential on an density
> isosurface. Thus I have two 3df files, one for potential and one for density.
>
> Similarly than in the figure in bottom of this page, except much more
> beautifully.
> http://www.cup.uni-muenchen.de/ch/compchem/pop/mep1.html
>
> I know how to do the isosurface, but I can't figure out how to set a 'volumetric
> texture' to it.

I guess you mean df3?

If we're talking about texturing the actual surface of the isosurface 
object, it should be as simple as:

isosurface {
   ...
   texture {
     pigment {
       density_file df3 "filename.df3" interpolate 1
       pigment_map {
         ...
       }
     }
   }
}


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From: mikaelk
Subject: Re: Display 3df data though a colormap on a isosurface from 3df
Date: 17 Jan 2014 08:35:00
Message: <web.52d930852df04bed271407fc0@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 14.01.2014 21:07, schrieb mikaelk:
> > Hello!
> >
> > In short, I would like to visualize the electrostatic potential on an density
> > isosurface. Thus I have two 3df files, one for potential and one for density.
> >
> > Similarly than in the figure in bottom of this page, except much more
> > beautifully.
> > http://www.cup.uni-muenchen.de/ch/compchem/pop/mep1.html
> >
> > I know how to do the isosurface, but I can't figure out how to set a 'volumetric
> > texture' to it.
>
> I guess you mean df3?
>
> If we're talking about texturing the actual surface of the isosurface
> object, it should be as simple as:
>
> isosurface {
>    ...
>    texture {
>      pigment {
>        density_file df3 "filename.df3" interpolate 1
>        pigment_map {
>          ...
>        }
>      }
>    }
> }

Thanks. That worked out of the box. So with volumetric texture, I meant that the
mapping is from x,y,z to u,v,w texture coordinates like that. Maybe a wrong
term.

It's still extremely slow though (several hours on quadcore i7) and looks
absolutely terrible materialwise. I need to reduce specular reflection at least.

I'm not sure why the step structure. I think it maybe related to my quantization
of data, which doesn't have enough bits.

http://imageshack.com/a/img35/7173/6j0u.png

The system is periodic in few directions. I think I could make it periodic in
povray using function statement for isosurface with some use of modulo function.


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From: clipka
Subject: Re: Display 3df data though a colormap on a isosurface from 3df
Date: 17 Jan 2014 11:07:17
Message: <52d95535@news.povray.org>
Am 17.01.2014 14:34, schrieb mikaelk:

> I'm not sure why the step structure. I think it maybe related to my quantization
> of data, which doesn't have enough bits.
>
> http://imageshack.com/a/img35/7173/6j0u.png

Maybe try "interpolate 2" on the df3 you're using for the isosurface.


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From: Alain
Subject: Re: Display 3df data though a colormap on a isosurface from 3df
Date: 17 Jan 2014 19:29:53
Message: <52d9cb01@news.povray.org>

> Am 17.01.2014 14:34, schrieb mikaelk:
>
>> I'm not sure why the step structure. I think it maybe related to my
>> quantization
>> of data, which doesn't have enough bits.
>>
>> http://imageshack.com/a/img35/7173/6j0u.png
>
> Maybe try "interpolate 2" on the df3 you're using for the isosurface.
>

Using interpolate 2, or even interpolate 1, should reduce the stepping. 
As a side effect, it will reduce the max_gradient allowing you to use a 
smaller value, probably resulting in a somewhat faster rendering.


Alain


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