POV-Ray : Newsgroups : povray.binaries.images : A shot in the dark Server Time
10 Aug 2024 01:28:44 EDT (-0400)
  A shot in the dark (Message 1 to 9 of 9)  
From: Carl
Subject: A shot in the dark
Date: 23 Nov 2004 20:00:00
Message: <web.41a3dcd08a8e13b3a54c62600@news.povray.org>
I used a scattering media and light sources to create the flash.  I expected
the media to scatter enough light to illuminate the front of the tank.
Looks like I'll need to turn on radiosity to do that.  I know emissive
media doesn't "emit" light but I thought scattering media would if it were
illuminated with a real light source.  Did I just pick poor settings or am
I wrong?

Enjoy,
Carl


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Attachments:
Download 'tanktest.jpg' (102 KB)

Preview of image 'tanktest.jpg'
tanktest.jpg


 

From: Alain
Subject: Re: A shot in the dark
Date: 23 Nov 2004 21:36:13
Message: <41a3f39d$1@news.povray.org>
Carl nous apporta ses lumieres ainsi en ce 2004-11-23 19:58... :

>I used a scattering media and light sources to create the flash.  I expected
>the media to scatter enough light to illuminate the front of the tank.
>Looks like I'll need to turn on radiosity to do that.  I know emissive
>media doesn't "emit" light but I thought scattering media would if it were
>illuminated with a real light source.  Did I just pick poor settings or am
>I wrong?
>
>Enjoy,
>Carl
>  
>
>
> ------------------------------------------------------------------------
>
Emissive media don't emit light in a normal sene, but it does in a 
radiosity one just like a high ambient surface does.

Alain


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From: Psychomech
Subject: Re: A shot in the dark
Date: 24 Nov 2004 14:11:18
Message: <41A4DCD4.3D71EEB6@charter.net>
looks like someone has been watching too much tron again :)

Carl wrote:

> I used a scattering media and light sources to create the flash.  I expected
> the media to scatter enough light to illuminate the front of the tank.
> Looks like I'll need to turn on radiosity to do that.  I know emissive
> media doesn't "emit" light but I thought scattering media would if it were
> illuminated with a real light source.  Did I just pick poor settings or am
> I wrong?
>
> Enjoy,
> Carl
>
>   ------------------------------------------------------------------------
>  [Image]


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From: Florian Brucker
Subject: Re: A shot in the dark
Date: 24 Nov 2004 17:48:52
Message: <41a50fd4$1@news.povray.org>
> I know emissive
> media doesn't "emit" light but I thought scattering media would if it were
> illuminated with a real light source.  Did I just pick poor settings or am
> I wrong?

None of the medias does emit light light a light_source. Emissive media 
"emits" light when you use radiosity (with "media on" specified in the 
radiosity block). This does not work with scattering media IMHO. If you 
want to fake that effect, I suggest trying some point lights with fading 
or some spotlights.


HTH,
Florian
-- 
camera{look_at-y*10location<8,-3,-8>*10}#local a=0;#while(a<999)sphere{
#local _=.01*a-4.99;#local p=a*.01-5;#local c=.01*a-4.995;<sin(p*pi)*5p
*10pow(p,5)*.01>sin(c*c*c*.1)+1pigment{rgb 3}}#local a=a+1;#end
/******** http://www.torfbold.com ******** http://www.imp.org ********/


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From: Anthony D  Baye
Subject: Re: A shot in the dark
Date: 26 Nov 2004 23:34:10
Message: <41A803C3.E97034D9@gold.sdsmt.edu>
Damn! You beat me to it.

I've been working on a similar concept, but I don't know that much about tanks.

Very cool tho.

ADB

Carl wrote:

> I used a scattering media and light sources to create the flash.  I expected
> the media to scatter enough light to illuminate the front of the tank.
> Looks like I'll need to turn on radiosity to do that.  I know emissive
> media doesn't "emit" light but I thought scattering media would if it were
> illuminated with a real light source.  Did I just pick poor settings or am
> I wrong?
>
> Enjoy,
> Carl
>
>   ------------------------------------------------------------------------
>  [Image]

--
//Anthony D. Baye, Student - Comp.Sci.
#default{pigment{rgb<0,.4,1>}finish{reflection 0.3 specular 0.6}}#macro
m(a,g,e)#local A=0;
#while(A<360)#local
am=a*.75;cylinder{vrotate(a*x,A*g*z),vrotate(am*x,(A+135)*g*z)e}
#local A=A+90;#end #local B=0;#while(B<360)sphere{a*x,e rotate B/2*g*z}#local
B=B+1;
#end #end m(2,1,.03)m(2,-1,.03)light_source{<-3,10,-15>,rgb
1}camera{location-7*z look_at 0}


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From: Carl
Subject: Re: A shot in the dark
Date: 29 Nov 2004 11:50:00
Message: <web.41ab523a6df40f10a54c62600@news.povray.org>
Florian Brucker <tor### [at] torfboldcom> wrote:
> None of the medias does emit light light a light_source. Emissive media
> "emits" light when you use radiosity (with "media on" specified in the
> radiosity block). This does not work with scattering media IMHO. If you
> want to fake that effect, I suggest trying some point lights with fading
> or some spotlights.

Thanks.  I was working on a test render with radiosity just now and I had
forgotten to add the "media on" line.

Am I to assume scattering media lit with a real light_source still won't
work with radiosity even when "media on" is used?  I'm about to find out.
If needed I'll go back and add some emissive media too.

Carl


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From: Carl
Subject: Re: A shot in the dark
Date: 29 Nov 2004 12:05:01
Message: <web.41ab566c6df40f10a54c62600@news.povray.org>
Thanks.  I don't really know that much about tanks either.  I just modeled
mine after the tank seen in TRON.  Actually its one of the pre-production
models seen here:

http://www.tron-sector.com/gallery/default.aspx?do=gallery&section=1&category=4&group=Tanks

The tread is different on the tank as seen in the movie.

I'd love to see your concept.  Please don't stop on my account,

Carl

"Anthony D. Baye" <ant### [at] goldsdsmtedu> wrote:
> Damn! You beat me to it.
>
> I've been working on a similar concept, but I don't know that much about tanks.
>
> Very cool tho.
>
> ADB


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From: Derek Chen-Becker
Subject: Re: A shot in the dark
Date: 15 Dec 2004 09:54:41
Message: <41C05030.4070704@chen-becker.org>
Carl wrote:
> I used a scattering media and light sources to create the flash.  I expected
> the media to scatter enough light to illuminate the front of the tank.
> Looks like I'll need to turn on radiosity to do that.  I know emissive
> media doesn't "emit" light but I thought scattering media would if it were
> illuminated with a real light source.  Did I just pick poor settings or am
> I wrong?
> 
> Enjoy,
> Carl
> 

Very nice, how did you get the outlines on the parts?. Just a thought, 
but you could also put a transparent distortion (ripple?) perpendicular 
to the muzzle to indicate the compression wave from the projectile.

Derek


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From: Carl
Subject: Re: A shot in the dark
Date: 15 Dec 2004 18:40:01
Message: <web.41c0ca6f6df40f10a54c62600@news.povray.org>
Derek Chen-Becker <pov### [at] chen-beckerorg> wrote:
> Very nice, how did you get the outlines on the parts?

There are basically 3 tricks I used.  Say this is the shape I wanted to
outline:

  box {<-50,20,-75>,<100,150,75>}
  sphere {<100, 120, -85>,75}

The strait edges I'd outline with cylinders connected by spheres.  For
simple perfectly round outlines I'd use tori.

So for the above shape I'd draw a sphere at each corner of the box:

  sphere{<-50,20,-75> 10}
  sphere{<-50,20,75> 10}
  sphere{<-50,150,-75> 10}
  sphere{<-50,150,75> 10}
  sphere{<100,20,-75> 10}
  sphere{<100,20,75> 10}
  sphere{<100,150,-75> 10}
  sphere{<100,150,75> 10}

The radius can be adjusted with the width of the outline.  Next is a
cylinder at each edge:

  cone {<-50,20,-75>, 10 <-50,20,75>, 10}
  cone {<-50,20,-75>, 10 <-50,150,-75>, 10}
  cone {<-50,20,-75>, 10 <100,20,-75>, 10}
  cone {<-50,150,75>, 10 <-50,150,-75>, 10}
  cone {<-50,150,75>, 10 <-50,20,75>, 10}
  cone {<-50,150,75>, 10 <100,150,75>, 10}
  cone {<100,20,75>, 10 <100,20,-75>, 10}
  cone {<100,20,75>, 10 <100,150,75>, 10}
  cone {<100,20,75>, 10 <-50,20,75>, 10}
  cone {<100,150,-75>, 10 <100,150,75>, 10}
  cone {<100,150,-75>, 10 <100,20,-75>, 10}
  cone {<100,150,-75>, 10 <-50,150,-75>, 10}

Next is the line formed by the intersection of the box and the sphere.  That
is drawn with this:

  intersection {
    box {<-60,10,-85>, <110,160,85>}
    sphere {<100,120,-85> ,85}
  }

And finally comes the outline of the sphere.  That is drawn with this:

  sphere {<100,120,-85>, 85.001
     texture {pigment {rgbt 1}}
     interior_texture {OUTLINE_TEXTURE_HERE} no_shadow no_reflection
  }

So as you can see the outline of my cannon is a far more complicated part
then the cannon itself.

Derek Chen-Becker <pov### [at] chen-beckerorg> wrote:
> Just a thought, but you could also put a transparent distortion
> (ripple?) perpendicular to the muzzle to indicate the compression
> wave from the projectile.

Very cool idea.  I like.  Do you have any suggestions oh how to code that?

Thanks,
Carl


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