POV-Ray : Newsgroups : povray.advanced-users : Evil Fog Server Time
30 Jul 2024 12:19:59 EDT (-0400)
  Evil Fog (Message 1 to 5 of 5)  
From: Josh Franklin
Subject: Evil Fog
Date: 22 Sep 1999 23:14:55
Message: <37E99AC9.7D7872FA@yahoo.com>
I'm trying to add fog into a scene, but for some reason, it messes up my
media objects. For example, I have a cylinder with media to simulate
fire...without fog it looks great, but when I add in fog, the cylinder
becomes visible like I gave it a filter pigment. does anyone know how to
get rid of this?


thanks
-Josh
here is the fog code:


//1 unit = 1 meter
fog {
	fog_type 2 distance 80 color rgbf < 0.6, 0.4, 0.6, 0.4 >
	turbulence 0.6 turb_depth 10
	omega .75 lambda 2.5 octaves 3
	fog_offset 0.8 fog_alt 1.3
}

//here is the fire
#declare fire =
cylinder {
	<0, 0.01, 0 >, < 0, 2, 0 >, 1
	pigment { color rgbf 1 }
	interior {
    	media {
      		emission 1.2
			intervals 20
			samples 1, 10
			confidence 0.9999
			variance 1/1000
			density {
				cylindrical
		        poly_wave pi
		        turbulence 1.1
		        color_map {
			          [0.0 color rgbt < 0, 0, 0, -1 > ]
			          [0.3 color rgbf <1, .45, 0, -.9 >]
			          [0.8 color rgbf <1, 1, 0, .8 >]
			          [1.0 color rgbt < 0, 0, 0, -1 > ]			          
		        } 
		        scale < 1.4, .8, .8 >
		        rotate 90*z rotate 85*y
      		}
    	}
	}
	hollow
}


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From: Bob Hughes
Subject: Re: Evil Fog
Date: 23 Sep 1999 05:27:47
Message: <37e9f293@news.povray.org>
'fog' and "invisible" container objects not looking right is a common
problem and there isn't a real good solution far as I know.  Best
thing you can try is to increase the container object 'filter' a
little above 1.  Might see if you can remove the fog filter value from
its vector too if you can without disrupting everything.
From what I've found it's a game of juggling transparency around until
you get a clear enough object.  If anyone knows another way I need to
write it down here.

Bob

Josh Franklin <sad### [at] yahoocom> wrote in message
news:37E99AC9.7D7872FA@yahoo.com...
> I'm trying to add fog into a scene, but for some reason, it messes
up my
> media objects. For example, I have a cylinder with media to simulate
> fire...without fog it looks great, but when I add in fog, the
cylinder
> becomes visible like I gave it a filter pigment. does anyone know
how to
> get rid of this?
>
>
> thanks
> -Josh
> here is the fog code:
>
>
> file://1 unit = 1 meter
> fog {
> fog_type 2 distance 80 color rgbf < 0.6, 0.4, 0.6, 0.4 >
> turbulence 0.6 turb_depth 10
> omega .75 lambda 2.5 octaves 3
> fog_offset 0.8 fog_alt 1.3
> }
>
> file://here is the fire
> #declare fire =
> cylinder {
> <0, 0.01, 0 >, < 0, 2, 0 >, 1
> pigment { color rgbf 1 }
> interior {
>     media {
>       emission 1.2
> intervals 20
> samples 1, 10
> confidence 0.9999
> variance 1/1000
> density {
> cylindrical
>         poly_wave pi
>         turbulence 1.1
>         color_map {
>           [0.0 color rgbt < 0, 0, 0, -1 > ]
>           [0.3 color rgbf <1, .45, 0, -.9 >]
>           [0.8 color rgbf <1, 1, 0, .8 >]
>           [1.0 color rgbt < 0, 0, 0, -1 > ]
>         }
>         scale < 1.4, .8, .8 >
>         rotate 90*z rotate 85*y
>       }
>     }
> }
> hollow
> }


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From: Ken
Subject: Re: Evil Fog
Date: 23 Sep 1999 05:51:03
Message: <37E9F77B.906B4EC5@pacbell.net>
Bob Hughes wrote:
> 
> 'fog' and "invisible" container objects not looking right is a common
> problem and there isn't a real good solution far as I know.
> Bob

  Either it is a bug or a design limitation from what I can tell. This
is becoming a common complaint/question with more people starting to
use the media function. I myself have worked the issue rather extensively
and not found a satisfactory solution to it.

-- 
Ken Tyler

See my 1000+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html


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From: Nieminen Juha
Subject: Re: Evil Fog
Date: 23 Sep 1999 07:06:01
Message: <37ea0999@news.povray.org>
Antoher thing is that you can't use media and radiosity at the same time.
This has a very logical explanation: The radiosity is calculated only when
the recursion level is less or equal to the recursion_limit value (AFAIK).
This means that when you have a container object, the ray leaving this object
will be at recursion level 3 (it has hit 2 surfaces) so no radiosity is
calculated when that ray hits something (or even if it's calculated, if
you have a very high recursion_limit, the result will not be the same
as at recursion level 1 (ie. the ray that is shot from the camera)).

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/


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From: Josh Franklin
Subject: Re: Evil Fog
Date: 23 Sep 1999 09:46:04
Message: <37EA2EB8.66DFC741@yahoo.com>
Ok, I HAVE found the problem with the scene and it was not any fault of
POV-Ray's. here is a line of code in the fog:

fog_type 2 distance 80 color rgbf < 0.6, 0.4, 0.6, 0.4 >

what is messing up my scene is the fact that the fog is filtering, I
tried taking out the filter value as Bob suggested and the scene looked
great. Also, I have had no problems with radiosity and media, although
in my scene there is no call for radiosity because there are not that
many different reflective surfaces.

Thanks for everyone's help,
-Josh

Nieminen Juha wrote:
> 
>   Antoher thing is that you can't use media and radiosity at the same time.
> This has a very logical explanation: The radiosity is calculated only when
> the recursion level is less or equal to the recursion_limit value (AFAIK).
> This means that when you have a container object, the ray leaving this object
> will be at recursion level 3 (it has hit 2 surfaces) so no radiosity is
> calculated when that ray hits something (or even if it's calculated, if
> you have a very high recursion_limit, the result will not be the same
> as at recursion level 1 (ie. the ray that is shot from the camera)).
> 
> --
> main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/


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