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From: LanuHum
Subject: Fire, df3 and Povray
Date: 27 Apr 2015 13:45:00
Message: <web.553e74ccccc887917a3e03fe0@news.povray.org>
Hi!
I can't think how to paint fire, having df3
Who will help?
Thanks!


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From: MichaelJF
Subject: Re: Fire, df3 and Povray
Date: 27 Apr 2015 15:05:01
Message: <web.553e88265de3d38edde9759b0@news.povray.org>
"LanuHum" <Lan### [at] yandexru> wrote:
> Hi!
> I can't think how to paint fire, having df3
> Who will help?
> Thanks!

df3-files are the POV approach to volumetric rendering. df3-files are voxel
based and so have limitations. In a way you have a 3-Space-matrix of a choosen

as a density in a media-statement. All values between this voxels are
nterpolated. You will find wonderful examples at Paul Bourkes Site:

http://paulbourke.net/miscellaneous/povexamples/

If you will put fire from Blender to POV, df3 may be the way most convenient but
still a stony one. The Parameters needed  additional to the df3-file are hard to
understand sometimes.

I'm still not happy with my first trial at df3-fires:

http://news.povray.org/povray.binaries.images/thread/%3Cweb.5243d5c9b8a21b1ba616448f0%40news.povray.org%3E/?ttop=399699
&toff=300

May be you will consider other ways to parametrize media. df3 is not the only
way.

Best regards,
Michael


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From: MichaelJF
Subject: Re: Fire, df3 and Povray
Date: 27 Apr 2015 15:15:01
Message: <web.553e89c65de3d38edde9759b0@news.povray.org>
"MichaelJF" <mi-### [at] t-onlinede> wrote:
> "LanuHum" <Lan### [at] yandexru> wrote:
> > Hi!
> > I can't think how to paint fire, having df3
> > Who will help?
> > Thanks!
>
> df3-files are the POV approach to volumetric rendering. df3-files are voxel
> based and so have limitations. In a way you have a 3-Space-matrix of a choosen

> as a density in a media-statement. All values between this voxels are
> nterpolated. You will find wonderful examples at Paul Bourkes Site:
>
> http://paulbourke.net/miscellaneous/povexamples/
>
> If you will put fire from Blender to POV, df3 may be the way most convenient but
> still a stony one. The Parameters needed  additional to the df3-file are hard to
> understand sometimes.
>
> I'm still not happy with my first trial at df3-fires:
>
>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.5243d5c9b8a21b1ba616448f0%40news.povray.org%3E/?ttop=3996
99
> &toff=300
>
> May be you will consider other ways to parametrize media. df3 is not the only
> way.
>
> Best regards,
> Michael

Sorry, the fire was not df3 in this image but in a later Version (but looking
very similiar).

Best regards,
michael


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From: LanuHum
Subject: Re: Fire, df3 and Povray
Date: 27 Apr 2015 15:45:01
Message: <web.553e91415de3d38e7a3e03fe0@news.povray.org>
"MichaelJF" <mi-### [at] t-onlinede> wrote:
> "LanuHum" <Lan### [at] yandexru> wrote:
> > Hi!
> > I can't think how to paint fire, having df3
> > Who will help?
> > Thanks!
>
> df3-files are the POV approach to volumetric rendering. df3-files are voxel
> based and so have limitations. In a way you have a 3-Space-matrix of a choosen

> as a density in a media-statement. All values between this voxels are
> nterpolated. You will find wonderful examples at Paul Bourkes Site:
>
> http://paulbourke.net/miscellaneous/povexamples/
>
> If you will put fire from Blender to POV, df3 may be the way most convenient but
> still a stony one. The Parameters needed  additional to the df3-file are hard to
> understand sometimes.
>
> I'm still not happy with my first trial at df3-fires:
>
>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.5243d5c9b8a21b1ba616448f0%40news.povray.org%3E/?ttop=3996
99
> &toff=300
>
> May be you will consider other ways to parametrize media. df3 is not the only
> way.
>
> Best regards,
> Michael

Simply I didn't see a way
Emission or absorption color can be only rgb, not a pattern.
color_map density gives out some uncontrollable negative
If the first color not black, that, in general becomes visible bound-box

box{<0,0,0>, <1,1,1>
    pigment{ rgbt 1 }
    hollow
    interior{ //---------------------
        media{ method 3
               emission <1,0.03421,0.01391>
                density{density_file df3 "/tmp/smoke_Smoke_Domain.df3"
                        color_map {
                        [0 rgb <0,0,0>]
                        [0.25 rgb <0,1,0>]
                        [0.5301 rgb <1,0.09352,0.5>]
                        [0.8101 rgb <0,0,1>]
                        [1 rgb <1,1,1>]
                       } // end color_map
               } // end of density
               samples 128 // higher = more precise
         } // end of media --------------------------
    } // end of interior

Yes, df3 not the only way of creation of fire.
In the Blender 249 for creation of very beautiful fire the system of particles
was used.
As particles the spheres animated on scale and post-processing were used by blur
nodes
Now it doesn't work in regular system of particles. The Blender has now no
opportunity to animate a particle within its birth and death. I wrote in the
exporter a code for realization of the old mechanism but how to add blur for
Povray I too don't know


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From: Stephen
Subject: Re: Fire, df3 and Povray
Date: 27 Apr 2015 16:07:37
Message: <553e9709$1@news.povray.org>
On 27/04/2015 20:42, LanuHum wrote:
> Yes, df3 not the only way of creation of fire.

You might want to look at Rune's Particle system.

http://runevision.com/3d/include/particles/

It is SDL and it might give you an idea or two.

I have only used it for water but I think that there is a fire example 
there.

I hope it helps

-- 

Regards
     Stephen


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From: MichaelJF
Subject: Re: Fire, df3 and Povray
Date: 28 Apr 2015 11:35:01
Message: <web.553fa8015de3d38ed2655d950@news.povray.org>
"LanuHum" <Lan### [at] yandexru> wrote:
>
> Yes, df3 not the only way of creation of fire.
> In the Blender 249 for creation of very beautiful fire the system of particles
> was used.
> As particles the spheres animated on scale and post-processing were used by blur
> nodes
> Now it doesn't work in regular system of particles. The Blender has now no
> opportunity to animate a particle within its birth and death. I wrote in the
> exporter a code for realization of the old mechanism but how to add blur for
> Povray I too don't know

I'm not quiet sure if I understand all of your remarks correctly. And since I
have no idea about the particle System used by Blender my answer may be
erroneous completely.

First a voxel within a df3-file can contain only a color and if the color at the
border of the box described by the df3-file is not black which is density zero
you will see the bounding box. So if you use df3 here you must assure that the
fire is inside this box completely.

The particle system by Rune Johansen proposed by Stephen uses an other approach
to visualise fire. It has collected some dust during the years but the
visualisation part may be useful to you. Fortunatelly Rune's website
(runevision.com) is online again. His examples are quiet impressive even after
all the years. Personally I investigated the water part only, so for fire you
must study his solutions yourself. His particle system itself is a very simple
one and in fact not really worth to be called a particle system since the
particles doesn't interact with each other (which will be nearly impossible with
POV). They interact only with environmental objects. But his examples are still
impressive and in this situations the simple System works fine enough.

As I stated above I have no idea of the implementation of the particle system
used by Blender. Usually ons has rules for the birth and death of a particle but
I think you must not bother about such rules. At the specific stage of the
simulation you will depict only the living particles are of interest. And then
only their location (and color). The direction and velocity can be ignored since
this parameters are only important for the next step of the simulation of the
particle system and not to depict the actual situation.

BTW: Your example is hard to understand without the df3-file...

Hope we come to an understanding here, best regards,
Michael


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From: Stephen
Subject: Re: Fire, df3 and Povray
Date: 28 Apr 2015 12:59:06
Message: <553fbc5a@news.povray.org>
On 28/04/2015 16:33, MichaelJF wrote:
> First a voxel within a df3-file can contain only a color and if the color at the
> border of the box described by the df3-file is not black which is density zero
> you will see the bounding box. So if you use df3 here you must assure that the
> fire is inside this box completely.

This is very true.
Another thing when using df3 files is that you can have several inside 
one media.
The example below is from an old test of a bi-cubic Mandelbrot I did 
about 10 years ago. (Andrew/Orchid supplied the code for me to make the 
df3 files.) I posted the code and instructions to make them in 
povray.binaries.misc 2005

I cannot remember why I used Red, Yellow and Blue.

#declare df3_cube01bddf_0 =
material{
   texture {
     pigment {
       color rgbft <1.000,0.000,0.000,0.000,1.000>
     }

   }

   interior{
     ior                 1.000
     caustics            0.000
     dispersion          1.000
     dispersion_samples  7.000
     fade_power          0.000
     fade_distance       0.000
     fade_color          rgb <0.000,0.000,0.000>
     media {
       method     3
       intervals  20
       samples    3, 6
       confidence 0.900
       variance   0.008
       ratio      0.900
       absorption rgb <0.000,0.000,0.000>
       emission   rgb <1.000,0.000,0.000>
       aa_threshold 0.100
       aa_level    4
       density {
         density_file df3 "F:\Graphics\B3D Data\Maps\DF3\Mikes05r2.df3"
         interpolate 1
         scale     <2.000,2.000,2.000>
         translate <-1.000,-1.000,-1.000>
       }

     }

     media {
       method     3
       intervals  20
       samples    3, 6
       confidence 0.900
       variance   0.008
       ratio      0.900
       absorption rgb <0.000,0.000,0.000>
       emission   rgb <0.000,0.000,1.000>
       aa_threshold 0.100
       aa_level    4
       density {
         density_file df3 "F:\Graphics\B3D Data\Maps\DF3\Mikes05b2.df3"
         interpolate 1
         scale     <2.000,2.000,2.000>
         translate <-1.000,-1.000,-1.000>
       }

     }

     media {
       method     3
       intervals  20
       samples    3, 6
       confidence 0.900
       variance   0.008
       ratio      0.900
       absorption rgb <0.000,0.000,0.000>
       emission   rgb <0.400,0.400,0.000>
       aa_threshold 0.100
       aa_level    4
       density {
         density_file df3 "F:\Graphics\B3D Data\Maps\DF3\Mikes05y2.df3"
         interpolate 1
         scale     <2.000,2.000,2.000>
         translate <-1.000,-1.000,-1.000>
       }

     }

   }

}


-- 

Regards
     Stephen


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From: LanuHum
Subject: Re: Fire, df3 and Povray
Date: 28 Apr 2015 14:15:01
Message: <web.553fcde05de3d38e7a3e03fe0@news.povray.org>
"MichaelJF" <mi-### [at] t-onlinede> wrote:

>
> BTW: Your example is hard to understand without the df3-file...
>

> Michael

Look my topic:
http://news.povray.org/povray.binaries.images/message/%3Cweb.553fcb648d10ac1c7a3e03fe0%40news.povray.org%3E/#%3Cweb.553
fcb648d10ac1c7a3e03fe0%40news.povray.org%3E


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From: Alain
Subject: Re: Fire, df3 and Povray
Date: 29 Apr 2015 19:14:26
Message: <554165d2$1@news.povray.org>
Le 15-04-28 12:58, Stephen a écrit :
> On 28/04/2015 16:33, MichaelJF wrote:
>> First a voxel within a df3-file can contain only a color and if the
>> color at the
>> border of the box described by the df3-file is not black which is
>> density zero
>> you will see the bounding box. So if you use df3 here you must assure
>> that the
>> fire is inside this box completely.
>
> This is very true.
> Another thing when using df3 files is that you can have several inside
> one media.
> The example below is from an old test of a bi-cubic Mandelbrot I did
> about 10 years ago. (Andrew/Orchid supplied the code for me to make the
> df3 files.) I posted the code and instructions to make them in
> povray.binaries.misc 2005
>
> I cannot remember why I used Red, Yellow and Blue.

Looking at your sampling parameters, and I say: "Ouch!"
1- With method 3, intervals must be set to 1. Any other value 
dramaticaly increase the rendering time, and may cause some artefacts.
2- samples only use the first value. If a second value is present, it 
will be silently ignored.
3- confidence, variance and ratio are NOT used in any way. The are 
specific to method 1 and 2 ONLY.

method 3 is the default method and don't need to be precised.

>
> #declare df3_cube01bddf_0 =
> material{
>    texture {
>      pigment {
>        color rgbft <1.000,0.000,0.000,0.000,1.000>
>      }
>
>    }
>
>    interior{
>      ior                 1.000
>      caustics            0.000
>      dispersion          1.000
>      dispersion_samples  7.000
>      fade_power          0.000
>      fade_distance       0.000
>      fade_color          rgb <0.000,0.000,0.000>
>      media {
>        method     3
>        intervals  20
>        samples    3, 6
>        confidence 0.900
>        variance   0.008
>        ratio      0.900
>        absorption rgb <0.000,0.000,0.000>
>        emission   rgb <1.000,0.000,0.000>
>        aa_threshold 0.100
>        aa_level    4
>        density {
>          density_file df3 "F:\Graphics\B3D Data\Maps\DF3\Mikes05r2.df3"
>          interpolate 1
>          scale     <2.000,2.000,2.000>
>          translate <-1.000,-1.000,-1.000>
>        }
>
>      }
>
>      media {
>        method     3
>        intervals  20
>        samples    3, 6
>        confidence 0.900
>        variance   0.008
>        ratio      0.900
>        absorption rgb <0.000,0.000,0.000>
>        emission   rgb <0.000,0.000,1.000>
>        aa_threshold 0.100
>        aa_level    4
>        density {
>          density_file df3 "F:\Graphics\B3D Data\Maps\DF3\Mikes05b2.df3"
>          interpolate 1
>          scale     <2.000,2.000,2.000>
>          translate <-1.000,-1.000,-1.000>
>        }
>
>      }
>
>      media {
>        method     3
>        intervals  20
>        samples    3, 6
>        confidence 0.900
>        variance   0.008
>        ratio      0.900
>        absorption rgb <0.000,0.000,0.000>
>        emission   rgb <0.400,0.400,0.000>
>        aa_threshold 0.100
>        aa_level    4
>        density {
>          density_file df3 "F:\Graphics\B3D Data\Maps\DF3\Mikes05y2.df3"
>          interpolate 1
>          scale     <2.000,2.000,2.000>
>          translate <-1.000,-1.000,-1.000>
>        }
>
>      }
>
>    }
>
> }
>
>

For your 3 medias, use this:
media{
  samples 100 // more samples and faster
  absorbtion...
  <rest of the media goes here>
}


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From: Stephen
Subject: Re: Fire, df3 and Povray
Date: 30 Apr 2015 01:10:51
Message: <5541b95b$1@news.povray.org>
On 30/04/2015 00:15, Alain wrote:
> Looking at your sampling parameters, and I say: "Ouch!"

So do I, now. :-)
IIRC they were the Moray defaults that were imported into Biship3D.
It was 10 years ago when I made the scene.

-- 

Regards
     Stephen


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