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1 Nov 2024 03:18:28 EDT (-0400)
  Liquid animation 7 (Message 1 to 8 of 8)  
From: fidos
Subject: Liquid animation 7
Date: 19 May 2005 16:15:01
Message: <web.428cf33ba3262ac44d40d3730@news.povray.org>
Helo,

I'm posting a new liquid animation.

I worked on the realism with the target to simulate a water movement.

It is the same simulation settings than in my last post : a cube falling in
a cup of water.

The object movement was computed with the MechSim patch of MegaPov 1.0.

I simulated a period of 2 seconds and I rendered it in 25 frames per
seconds.

For the rendering, I double the number of photons when comparing to my last
post.

The video is MPEG1 encoded.

Your opinion is wellcome.

Regards,
Fidos


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Attachments:
Download 'cup.mpg' (687 KB)

From: Marneus Calgar
Subject: Re: Liquid animation 7
Date: 21 May 2005 04:55:41
Message: <428ef78d@news.povray.org>

> Helo,
> 
> I'm posting a new liquid animation.
> 
> I worked on the realism with the target to simulate a water movement.
> 
> It is the same simulation settings than in my last post : a cube falling in
> a cup of water.
> 
> The object movement was computed with the MechSim patch of MegaPov 1.0.
> 
> I simulated a period of 2 seconds and I rendered it in 25 frames per
> seconds.
> 
> For the rendering, I double the number of photons when comparing to my last
> post.
> 
> The video is MPEG1 encoded.
> 
> Your opinion is wellcome.
> 
> Regards,
> Fidos

The water effects is really great, and the lighting effects too, but 
when the water run downs, it goes too slow, and it looks a bit like gel !

Otherwise, it is perfect !


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From: dlm
Subject: Re: Liquid animation 7
Date: 23 May 2005 15:21:19
Message: <42922d2f@news.povray.org>
Fidos,
I've been watching this series with interest. Nice work!
At least in the earlier opaque fluid renditions the fluid seems to be more 
viscous than 'ordinary' water.
What physical parameters do you model?
Viscosity , density, temperature for liquid and gas phases? Anything else 
like surface tension or container surface properties?
What is the dimensional scaling like?
Certainly your latest image has a generally good feel about it.
The drops on the container surface seem to contract away from the rebounding 
wave. This seems unrealistic. The falling cube seems to set up a very 
symmetrical pattern.
Math economy?
Or perhaps you might introduce a little twist?
Best,
DLM





"fidos" <fid### [at] wanadoofr> wrote in message 
news:web.428cf33ba3262ac44d40d3730@news.povray.org...
> Helo,
>
> I'm posting a new liquid animation.
>
> I worked on the realism with the target to simulate a water movement.
>
> It is the same simulation settings than in my last post : a cube falling 
> in
> a cup of water.
>
> The object movement was computed with the MechSim patch of MegaPov 1.0.
>
> I simulated a period of 2 seconds and I rendered it in 25 frames per
> seconds.
>
> For the rendering, I double the number of photons when comparing to my 
> last
> post.
>
> The video is MPEG1 encoded.
>
> Your opinion is wellcome.
>
> Regards,
> Fidos
>


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From: Tim Nikias
Subject: Re: Liquid animation 7
Date: 23 May 2005 16:29:57
Message: <42923d45$1@news.povray.org>
Very nice! But still not water, though closer. I'm not sure, maybe the waves
travel too slow and/or the resolution of the water is too low. The way it
sticks to the waterbowl suggests too low resolution, and makes it look real
"sludgy". Maybe you should try and take some film with an effect and try to
recreate it, so that you have something to compare.

And I'd be interested in the same things as DLM: what do you simulate and
have in your model, viscosity, heat, surface tension...? Maybe some of the
settings can be taken directly from some data known about water. Maybe it's
just a computational problem and you should decrease step-size and increase
resolution or such. How long did this one take to simulate?
-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: fidos
Subject: Re: Liquid animation 7
Date: 24 May 2005 14:20:00
Message: <web.42937015445c3667f4eef7550@news.povray.org>
I only use the density of the fluid. I removed the diffusion term in the
Navier Stock equation. I don't model the tension surface.

Tim, you are right, the "sludgy" effect is only computational problems.

Yesterday, I anderstood that the fluid->water model that I use make the
water to stick to the object. In fact, if the water speed is greater than
than the object one, water and object should seperate.

Moreover, I'm rewriting the pressure computation on the free liquid surface.
I will model the tension surface because I have the feeling it is very
important for visual effects. I found some papers about it and it looks
very simple to do.

The simulation time was around 15 hours (I reduced it by half from my last
post !). The rendering time was very long (around 48 hours).

TLM, there is no symetrical optimisation. You are right, some cube twist
would be useful in order to break the symetry. The simulation domain is
1x1x1 cube with a 100x100x100 grid resolution. Everything is dimension
less.

Regards,
Fidos


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From: triple r
Subject: Re: Liquid animation 7
Date: 29 May 2005 11:35:00
Message: <web.4299e0ed445c3667e702b90a0@news.povray.org>
"fidos" <fid### [at] wanadoofr> wrote:
> It is the same simulation settings than in my last post : a cube falling in
> a cup of water.

Splash!    Splash??  I have done some of this stuff with limited success, so
first things first, that is an amazing simulation.  Excellent work.  BUT,
it does look too viscous and there is no splash.  I'm not critiquing your
work, only the limitations of the model.  I don't know how the viscosity
could be decreased since the only viscosity is due to the model itself, not
a viscosity term, but is it possible to add some particles?  Maybe if the
surface of the liquid decelerates too quickly, it will spawn blob particles
or something.  I've seen some work before with a mixture of simple
particles and grid-based fluid simulation.  (Also particle-based fluid
simulation, but that's another topic altogether.)  Maybe not worth the
trouble or possible, but the lack of a splash in a face-to-face collision
seems fishy - no pun intended.  Ooh, maybe a goldfish?

- Ricky


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From: Dan Byers
Subject: Re: Liquid animation 7
Date: 30 May 2005 11:20:01
Message: <web.429b2ed8445c3667b4698d3a0@news.povray.org>
"fidos" <fid### [at] wanadoofr> wrote:
> Helo,
>
> I'm posting a new liquid animation.
>
> I worked on the realism with the target to simulate a water movement.
>
> It is the same simulation settings than in my last post : a cube falling in
> a cup of water.
>
> The object movement was computed with the MechSim patch of MegaPov 1.0.
>
> I simulated a period of 2 seconds and I rendered it in 25 frames per
> seconds.
>
> For the rendering, I double the number of photons when comparing to my last
> post.
>
> The video is MPEG1 encoded.
>
> Your opinion is wellcome.
>
> Regards,
> Fidos

Excellent work -- your experiments are really coming together.  My only
criticism is an object that large falling into a bowl of water at that
angle would kick about of the water out of the bowl, but I'm operating
under the assumption you're not too worried about that at this stage.  Keep
on rendering! :)
------------------------
Dan
GoofyGraffix.com


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From: Numb-C
Subject: Re: Liquid animation 7
Date: 11 Aug 2005 03:20:00
Message: <web.42fafc0a445c3667726bd13c0@news.povray.org>
Hi Fidos,

Since the first time I saw Jos Stam on tv showing some smoke simulations I
got interested in Smoke and Fluids simulations.

A month ago I finally decided to start reading up on documentation (pretty
much the links you provided in earlier threads) to start writing smoke and
fluid simulations in C# / OpenGL.

Last week I also started working with POV-Ray again (last time I worked with
it was version 1.0 or alike) intentionally to create abstract scenes
(spheres / fractals ect..). So I really was quite intrigued reading your
Fluid threads. I love your experimentations and will keep following them
from now on while I start with my first steps in this expertise (I'll start
of with smoke simulations I think).

Seems I have a lot of reading to do now for combining code with POV-Ray too
:)
Thanks for the insipiration and if you have some good pointers where I
should start with let me know !

Best regards,
NumbC


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