How did they do it?

[Tom]

Hello Hashers-

 

I was watching the "Secret of Kells" and saw some cool smoke effects which have me stumped.

They used celtic spirals for the rising smoke and the outer spiral lines changed from white to dark when they crossed some sort of masking line.(see animated clip).

 

I'm sure there is a pretty simple explanation how they achieved this effect..but I can't figure it out.

 

Can anyone explain this cool effect?

 

Many thanks,

Tom

SmokeQuestion.swf

[Fuchur]

very likely a simple mask with a blury edge in after effects where they use either a multiply effect or two layers above each other blending one out and the other in with the mask.

 

see you

*fuchur*

[robcat2075]

Unfortunately i couldn't play the SWF.

[Tom]

Sorry you couldn't play the clip Robcat.

 

It is a pretty cool the way the animators swap out the spirals in the clip; the spirals change from a light to dark outline as they pass that section of the screen...very effective.

 

I am thinking about what Fuchur said regarding the technique. Yes, two layers on top of each other sounds like a good solution.

 

Thanks !!

 

Tom

[John Bigboote]

Yup- post-production.

[KJ'd Beast]

Rob,

I converted it to QuickTime.


Tom,

If you scrub through the QT file you can see it appears to be multiple copies of the same "smoke" image, layered and rotating and growing at different rates.

It appears that you could do this with a particle emitted sprite that rotates, grows, and changes color over time.

SmokeQuestion.mov

Edited September 16, 2014 by KJ'd Beast

[pixelplucker]

Would have to test but should be possible with an animated texture on a sprite.

[Rodney]

Thought folks might get a kick out of this failed Proof of Concept:

 

 

There does appear to be some post work done in this but the primary elments appear to be:

 

1 ) Fire spirals rotate one way while the smoke rotates in the opposite.

2 ) Fire spirals move up while the smoke spirals move down

3 ) The smoke spirals appear to be on an overlay that has a mask with circular opening at the bottom left (to allow the fire spirals to appear)

 

Although particles could be used I think this is more of a repetition on 2D planes that is then composited.

In other words... the fire spirals rendered moving upward. The smoke spirals rendered coming downward. The smoke then composited over the fire..

 

As for how the lighter lines turn to dark lines it looks to me as if the images are negatives of each other.

In the fire the lines are white (or light color) and the centers black (or dark color) while in the smoke the lines are black (or dark color) while the centers white (or light color).

The color is then added/composited over that.

POC (fail).mov

[robcat2075]

Here is my 15 minute simple version with a sprite. The color of the sprite is animated in the channels in the material. You can load this and play it.

 

 

KellSquiggles03.prj

 

Edit: you'll need to download this PNG for the sprite...

 

[Tom]

Many thanks for all the creative thinkers out there who pitched in to deconstruct this!

 

What a great forum!!!

 

Tom