Hi,
    Can anyone recommend what media settings I should use to get a light
scattering of dust in the air? All I can get at the moment is the dust
glowing brilliant white. I want to see subtle shadows cast on the atmosphere
in an otherwise normally lit room.

Thanks,

Andy

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Andrew Cocker wrote:
> 
> Hi,
>     Can anyone recommend what media settings I should use to get a light
> scattering of dust in the air? All I can get at the moment is the dust
> glowing brilliant white. I want to see subtle shadows cast on the atmosphere
> in an otherwise normally lit room.
> 
> Thanks,
> 
> Andy


Here are a couple of examples of using scattering
media. It would work best if used with spot light
sources but will work with point lites as well.


This first one is fairly weak but effective. It will
depend on how much light there is in the scene as too
how well it will work. If you put it in sunlight don't
expect much but snow blindness. I will also be distance
sensitive.

media{
 intervals 10
  scattering{1,rgb .03}
   samples 1,10
   confidence .9999
  variance 1/1000
 ratio .9
}


This second one will add a little more haze to the
scene than the first but between the two maybe you
can figure our which way to go.

media{
 intervals 40 
  scattering{1, rgb .02}
   samples 1,10 
   confidence .9999
  variance 1/1000
 ratio .9
}


Ken Tyler

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Thanks Ken, that's helped somewhat, although I still have a related
problem.
I'm modelling a room with a large hole in the roof, through which my
spotlight is shining and interacting with the atmosphere in the room. The
problem is that I also have a sky_sphere, but it disappears as soon the
media is activated. Basically, I can't see through and 'out of' the media.
    I have tried enclosing the media in a hollow box the same size as the
room, but the problem persists. The media is working within the room just
how I want it, but I want to be able to see the sky.
    Any ideas would be appreciated,

Thanks,
Andy.

Ken wrote in message <367### [at] pacbellnet>...

>Here are a couple of examples of using scattering
>media. It would work best if used with spot light
>sources but will work with point lites as well.
>
>
>This first one is fairly weak but effective. It will
>depend on how much light there is in the scene as too
>how well it will work. If you put it in sunlight don't
>expect much but snow blindness. I will also be distance
>sensitive.
>
>media{
> intervals 10
>  scattering{1,rgb .03}
>   samples 1,10
>   confidence .9999
>  variance 1/1000
> ratio .9
>}
>
>
>This second one will add a little more haze to the
>scene than the first but between the two maybe you
>can figure our which way to go.
>
>media{
> intervals 40
>  scattering{1, rgb .02}
>   samples 1,10
>   confidence .9999
>  variance 1/1000
> ratio .9
>}
>
>
>Ken Tyler

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Hi,
    I sort of found a solution to the problem by using a cloud plane. I
guess the problem is that sky_sphere's are so large. I'd still be interested
to know if I was doing something wrong.

    Thanks again,

Andy

Post a reply to this message

Andrew Cocker wrote:
> 
> Hi,
>     I sort of found a solution to the problem by using a cloud plane. I
> guess the problem is that sky_sphere's are so large. I'd still be interested
> to know if I was doing something wrong.
> 
>     Thanks again,
> 
> Andy

You are probably not doing anything wrong. The way
the sky sphere is implemented in pov is in a virtual
way. Think of it as a multi colored fog that exsists
everywhere a solid object doesn't. The way media is
implemented I suspect (and I'm guessing here) is that
the program is getting confused by the two similar yet
different functions and the media is winning the war.
I applaud yuor cure to the problem as it was what I
was going to suggest after reading your second post.
Fortunatly I decided to read this one first.

For a great tutorial on applying cloud textures to
planes and spheres take a look at:

http://members.xoom.com/POVRAY3/index2.html

Very well done tutorial with images and source code
available to learn from.

Ken Tyler

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For what it's worth, (probably not much considering my level of
expertise) I've been having a similar problem with a couple of my scenes
and I found that adding "extinction 0" to the media setting helped quite
a bit.  It made my sky sphere visible again gave me the "cone" of
scattering that I was looking for.  Also setting "media interaction
off"  for fill lights and using spotlights instead of point lights made
things easier to control.

Best,

Mike Wilson


Andrew Cocker wrote:

> Hi,
>     I sort of found a solution to the problem by using a cloud plane.
> I
> guess the problem is that sky_sphere's are so large. I'd still be
> interested
> to know if I was doing something wrong.
>
>     Thanks again,
>
> Andy

Post a reply to this message