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Hash, Inc. Forums > Technical Direction and Development (Learning Animation:Master) > A:M Rendering, Compositing and Special Effects
Tom
Hello-

Playing with sprite smoke and wanted to ask two questions.

1) Is it possible to achieve an effect like the one in the still image from a 2D Disney cartoon whereby smoke is underlit to give a dramatic effect?

Sprites don't seem to be affected by lights and if you colored the individual small graphic (which makes up the smoke ) to be underlit, then the underlit effect would be over the entire smoke cloud and not isolated as it would be in a dramatic setting...

2) I have been trying to get a very slow (almost hypnotic) effect with smoke rising using sprites. Can't seem to slow the smoke down enough to get that effect. I tried playing with the "initial velocity" and "gravity" settings with no luck. You could take a Hash smoke render and slow it down by time stretching it in After Effects but that is a cheat and it wouldn't look great.

Attached is a slow smoke "boil" from a Dark tree animation. Unfortunately it's not 3D. but maybe it gives an idea of the desired effect.

Thanks for any suggestions,

Tom
robcat2075
QUOTE(Tom @ Aug 22 2009, 12:08 PM) *
Hello-

Playing with sprite smoke and wanted to ask two questions.

1) Is it possible to achieve an effect like the one in the still image from a 2D Disney cartoon whereby smoke is underlit to give a dramatic effect?

Sprites don't seem to be affected by lights and if you colored the individual small graphic (which makes up the smoke ) to be underlit, then the underlit effect would be over the entire smoke cloud and not isolated as it would be in a dramatic setting...


You're right. Sprites have no real volume so they can't shade like real shapes.

I think that effect is a bit more like a fluid simulation. Think of an aquarium filled with clear water and then pouring a half cup of milk into it. If you filmed that in super slow motion and turned it upside down you'd get something like that mushroom cloud effect. I think that's actually been done in some movies.

Could A:M fluids do that? maybe. You'd have to learn a lot about what the various settings do.

BTW, isn't it amazing that someone can DRAW that smoke?


QUOTE
2) I have been trying to get a very slow (almost hypnotic) effect with smoke rising using sprites. Can't seem to slow the smoke down enough to get that effect. I tried playing with the "initial velocity" and "gravity" settings with no luck. You could take a Hash smoke render and slow it down by time stretching it in After Effects but that is a cheat and it wouldn't look great.


-someone did some cigarette smoke here recently

-high viscosity slows particle motion

-does baking particle make keyframes? If so, you could stretch them out to slow things down.
Tom
QUOTE(robcat2075 @ Aug 22 2009, 11:16 AM) *
QUOTE(Tom @ Aug 22 2009, 12:08 PM) *
Hello-

Playing with sprite smoke and wanted to ask two questions.

1) Is it possible to achieve an effect like the one in the still image from a 2D Disney cartoon whereby smoke is underlit to give a dramatic effect?

Sprites don't seem to be affected by lights and if you colored the individual small graphic (which makes up the smoke ) to be underlit, then the underlit effect would be over the entire smoke cloud and not isolated as it would be in a dramatic setting...


You're right. Sprites have no real volume so they can't shade like real shapes.

I think that effect is a bit more like a fluid simulation. Think of an aquarium filled with clear water and then pouring a half cup of milk into it. If you filmed that in super slow motion and turned it upside down you'd get something like that mushroom cloud effect. I think that's actually been done in some movies.

Could A:M fluids do that? maybe. You'd have to learn a lot about what the various settings do.

BTW, isn't it amazing that someone can DRAW that smoke?





QUOTE
2) I have been trying to get a very slow (almost hypnotic) effect with smoke rising using sprites. Can't seem to slow the smoke down enough to get that effect. I tried playing with the "initial velocity" and "gravity" settings with no luck. You could take a Hash smoke render and slow it down by time stretching it in After Effects but that is a cheat and it wouldn't look great.


-someone did some cigarette smoke here recently

-high viscosity slows particle motion

-does baking particle make keyframes? If so, you could stretch them out to slow things down.




Thank you for the reply!

I was thinking there might be a way to get two tone sprite smoke. Use two separate emittors with two separate colored sprites and have one start a little before and behind the other one. I'll have to experiment but I agree that this is probably a fluid simulation situation if this previous idea doesn't work.

Yeah-the 2D guys really could create effects. There is another great hand drawn cloud plume in Disney's "Brother Bear". It's the scene where the female shaman is giving the girl advice in the cave. It's a cycle but done so effectively you barely notice.

BTW- I looked for the cigarette smoke on the forum but couldn't find it. Do you know a link?

Many thanks!

Tom
johnl3d
you could do this I believe with sprites at two different levels or a smoke like effect could be done with gradient animated material on a model
I'm at work now but can try to get an example later
robcat2075
here's a sample PRJ that shows slow drifting streak particles.

Click to view attachment

Click to view attachment



it uses very large particles that are 99% transparent. (this is why they don't show in the chor)

more particles, more transparent would make better smoke.

they have no gravity, low velocity, very slight viscosity, long life.

one large weak force with weak turbulence hits them to disperse them slightly.

I'm not saying this is your finished effect. This is proof of concept that such things can be done. With fine tuning of the various elements I think any desired effect can be had.
Tom
That is wonderful!

Thanks!

Tom

BTW- Here is the hand drawn Smoke cycle from Brother Bear...
JavierP
Hi,
I have not posted on this forum in a while, but your question reminded me of some tests I had done a long time ago.

Click to view attachment

The effect you want can be achieved, but it would take a bit of work to animate it properly. Nothing really fancy, just a model with materials controlling displacement, color and transparency. The addition of streak particle emitters and a little blurring finishes the effect. It would probably be better to render the smoke separately and then composite to really control the softness. Hope this helps.
Tom
That sounds like an interesting approach...

Do you happen to have any animation showing how it looked in motion?

Thanks!

Tom
JavierP
Sorry I wasn't a bit more clear. The image I posted was just a quick test I made to approximate the example you posted. I haven't animated it yet, and I don't have any of the tests I originally did, but it is a fairly straight-forward process. Animation would be done with muscle mode transformations of the mesh, or a few bones applied to the mesh to control the scale, rotation etc. The timing would be a little tricky to set up, especially for the transformation of the materials, but with a little forethought, it could be accomplished. I'll see if I can make a quick and dirty example to show.
JavierP
Here is a quick motion test without particles. Certainly rough, but with some time the desired timing and overall effect of the plume could be perfected. Hope this helps.

Click to view attachment
Shelton
Nice fx!

Steve
Rodney
Nice one Javier!

It's great to see you again. smile.gif
robcat2075
QUOTE(JavierP @ Aug 29 2009, 06:07 AM) *
Here is a quick motion test without particles. Certainly rough, but with some time the desired timing and overall effect of the plume could be perfected. Hope this helps.

Click to view attachment


That look's like what he was looking for! Can you post a PRJ?
Tom
QUOTE(JavierP @ Aug 29 2009, 04:07 AM) *
Here is a quick motion test without particles. Certainly rough, but with some time the desired timing and overall effect of the plume could be perfected. Hope this helps.

Click to view attachment



That looks great!!

I agree with Robcat....is there a Project file you can post?

Best,

Tom
JavierP
Here is the prj file:

Click to view attachment

Made in version 13. It's structure is a bit messy as far as my project files go, but it was a sort of a rushed example. One thing to keep in mind is that I created it with no real application in mind other than the smoke image itself. Serious planning in advance (i.e. camera angles, duration of shot, lighting etc.) would be required to make any kind of useful effect. Hope it shines some light on the answers you are looking for.

Javier
Tom
QUOTE(JavierP @ Sep 15 2009, 12:19 AM) *
Here is the prj file:

Click to view attachment

Made in version 13. It's structure is a bit messy as far as my project files go, but it was a sort of a rushed example. One thing to keep in mind is that I created it with no real application in mind other than the smoke image itself. Serious planning in advance (i.e. camera angles, duration of shot, lighting etc.) would be required to make any kind of useful effect. Hope it shines some light on the answers you are looking for.

Javier



Thanks for posting the project!
Can't wait to play with it!

Tom
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