Thomas Lake <tla### [at] homecom> wrote in message
news:3984B880.628499B3@home.com...
> I really like the shape of the largest bubble, on top, but the smaller
> bubbles right under it don't look right somehow, they sort of make it look
> like a UFO or something.

You could be right.. I'm just working from intuition and guesswork. I
suppose I should have done a web search for some good still shots of air
bubbles first.

David

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David Heys <sou### [at] gcinet> wrote in message
news:3984971a@news.povray.org...
> With the talk of water bubbles, I thought I'd take a shot at making some.
>
> David

Nice positioning but it looks a little too symmetric, and shouldn't it be
somewhat transparent?

-Chris-

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> Nice positioning but it looks a little too symmetric, and shouldn't it be
> somewhat transparent?

Actually, the bubbles are all "rgbt 1" with no normal or finish properties.
What gives them their look is the ior of the box with the scattering media,
and making the bubbles non-hollow so the media is not inside them. I figured
they'd be symetrical, simply from the relatively uniform pressures of the
water. Figuring that the only things to make them non-uniform would be
collisions with other objects and bubbles.

David

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The shape is a little too regular, making it look more like a jellyfish.  I
think air bubbles are more concave on the bottom with smaller bubbles
clinging to the bottom edge.  Perhaps making them all blobs and putting some
negative blob components inside would help.  I don't know, just thinking out
loud.

-Mike

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Kick-ass bubbles man!

--
David Fontaine     <dav### [at] faricynet>     ICQ 55354965
Please visit my website: http://www.faricy.net/~davidf/

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David Heys <sou### [at] gcinet> wrote in message
news:3984e910@news.povray.org...
> I figured they'd be symetrical, simply from the relatively uniform
pressures of the
> water. Figuring that the only things to make them non-uniform would be
> collisions with other objects and bubbles.

You're probably right...but when is water pressure uniform?  Even in
swimming pools there are slight currents jostling bubbles into odd shapes.
Still, the general shape does look pretty good and lives up to DeWitt's
jellyfish theory.

I know the scene is meant just for test purposes but what really strikes me
is the media.  It looks quite natural and works well.  Do you think you
could e-mail me the source?

-Chris-

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Chris S. <chr### [at] bluelectrodecom> wrote in message
news:3985e47b@news.povray.org...
> You're probably right...but when is water pressure uniform?  Even in
> swimming pools there are slight currents jostling bubbles into odd shapes.
> Still, the general shape does look pretty good and lives up to DeWitt's
> jellyfish theory.

Good point about the currents. Temperature gradients would also play a
factor.

> I know the scene is meant just for test purposes but what really strikes
me
> is the media.  It looks quite natural and works well.  Do you think you
> could e-mail me the source?

Since you asked so nicely, I've posted the source for the scene to p.b.s.f.
:{)
The media, as you'll see, has a simple turbulated marble density map. In my
mind, it seemed like a quick cheat to simulate light rays beaming down into
the water.

David

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Mike <Ama### [at] aolcom> wrote in message news:3984FF86.4D0CFAF6@aol.com...
> The shape is a little too regular, making it look more like a jellyfish.
I
> think air bubbles are more concave on the bottom with smaller bubbles
> clinging to the bottom edge.  Perhaps making them all blobs and putting
some
> negative blob components inside would help.  I don't know, just thinking
out
> loud.

Nods.. Agreed.. The top bubble is a blob with a negative component pushing
up from below. Trick is, you'd really need to make each bubble a separate
blob object. Otherwise the smaller positive components would just be
swallowed up by the large negative component.

David

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On Sun, 30 Jul 2000 18:41:37 -0800, David Heys wrote...
> > Nice positioning but it looks a little too symmetric, and shouldn't it be
> > somewhat transparent?
> 
> Actually, the bubbles are all "rgbt 1" with no normal or finish properties.
> What gives them their look is the ior of the box with the scattering media,
> and making the bubbles non-hollow so the media is not inside them. I figured
> they'd be symetrical, simply from the relatively uniform pressures of the
> water. Figuring that the only things to make them non-uniform would be
> collisions with other objects and bubbles.

You forgot hydrodynamic drag, turbulence and general chaotic effects.

What you tend to get with bubbles over a certain size is what looks a bit 
like a SOR of the following (very bad) ascii graphic:

----___
       ---__
            -
----_________)
            ***
            ****
           ******

In the region marked by *'s, you get a random assortment of smaller, 
usually mostly spherical bubbles.

Also, as the bubble rises, it expands (Boyle's law, anyone?) and splits 
into multiple bubbles when turbulence etc overcome surface tension.

But I'm not dismissing you effort, it looks remarkably pretty, and I'm 
not sure if I could do any better given a couple of months to try <grin>

Bye for now,
     Jamie.

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David Heys <sou### [at] gcinet> wrote in message
news:3985f897@news.povray.org...
> Since you asked so nicely, I've posted the source for the scene to
p.b.s.f.
> :{)
> The media, as you'll see, has a simple turbulated marble density map. In
my
> mind, it seemed like a quick cheat to simulate light rays beaming down
into
> the water.
>
> David

Great, thanks.  Heh, any cheat for underwater light rays is ok with me;)

-Chris-

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