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Difficult fog/mist compositing

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Stuart SamuelsDifficult fog/mist compositing
by on Jun 16, 2013 at 12:53:20 pm

Hi.

I'm working on a short film and have been asked to add some mist to a number of shots. The majority are relatively easy but I'm struggling with this one...

Fog/Mist




Could anyone suggest a way to make it appear as though the boy is walking through mist within the forest? I'm assuming it may involve 3d camera tracking, depth maps and Particular. I can imagine the depth maps would be a rotoscoping nightmare so if there's another way around I'd be really greatful for your suggestions.

Thanks.


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Joseph W. BourkeRe: Difficult fog/mist compositing
by on Jun 17, 2013 at 12:33:27 am

I think that it would be relatively easy to use the Roto Brush to mask around the boy. The mist will depend on whether you're looking to get "ground" mist, which sits to a certain height above the ground, or just a general light fog, which would be at all levels in the shot. Of course, with real fog, as the boy walked through it, you would get a certain disturbance resulting in a swirl of the fog around the boy's outline. You also would need several levels of the fog, going away into the distance, since the more distance, the thicker the fog appears to be. You might achieve this with multiple layers of noise, in a very lightly swirling animation. Particular might do it, but I think it might be overkill.

As far as the color temperature of the scene; you could go quite a ways toward realism by changing the color temperature of the shot towards a bluer caste, but only in front of the boy (if you Roto Brush him).

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Stuart SamuelsRe: Difficult fog/mist compositing
by on Jun 17, 2013 at 4:14:54 pm

Thanks for that, that's great.
Could I ask how would you create the layers of fog? I was assuming something like Particular would be the way to go as I would be able to stretch it through Z space and can't really think how else I could achieve the look.

Thanks again.


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Joseph W. BourkeRe: Difficult fog/mist compositing
by on Jun 17, 2013 at 5:55:05 pm

I would use the Turbulent Noise effect which comes with AE. There are several settings which are pretty close to the slow, billowing you'd need for fog. Once you get close to what you want, you might start using the Brainstorm feature, which, once you've chosen a few parameters in the Fractal Noise effect, will randomly change them to give you a wide array of choices:

https://www.video2brain.com/en/lessons/brainstorming-1

Here's some info on Turbulent Noise:

http://help.adobe.com/en_US/aftereffects/cs/using/WS3878526689cb91655866c11...

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Matthew RossRe: Difficult fog/mist compositing
by on Jun 17, 2013 at 6:12:16 pm

The 2001 movie The Others did something like this--Nicole Kidman's character was walking along in the woods and they slowly became more and more foggy. I believe the DVD extras talked about the process, but as I recall, you would basically have to isolate all the objects in the shot that are at different distances from the camera and then apply different opacities of fog to them. If you don't need any kind of turbulence in the fog, just layers of white would probably do.

This would be a very painstaking process though, because you'd have to go through and rotoscope pretty much every tree, section of ground, etc., in addition to the character, in order to treat them as different depths. It's a similar process to how 3D is added in post to movies that were shot 2D.

Here's the sequence from The Others:







And here's an article on adding 3D after-the-fact to Jurassic Park, which would be a similar process:

http://flavorwire.com/382554/jurassic-park-how-a-2d-movie-becomes-a-3d-movi...

In the "old days," some films would fake fog by putting a fog filter on the camera, but the problems was that the entire shot had the same level of fog, rather than more distant objects being more obscured, so it always looked fake.

If you want to do this, and you want it to look good, you've got a lot of work ahead of you!


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Stuart SamuelsRe: Difficult fog/mist compositing
by on Jun 19, 2013 at 4:10:31 pm

Thanks for all that. That's kinda the method I was imagining actually.
I've had some good preliminary results with the Turbulent Noise effect but may look into the technique you described from The Others to see if it will be doable on my timescale.

Thanks so much for your help.

Stuart


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Clay CouchRe: Difficult fog/mist compositing
by on Jul 7, 2013 at 2:53:50 pm

Go to 12:39 in the video and see if this is what your looking for. He does this really simple, which I assume is what your looking for. You could thicken it up a bit and probably get what your looking for.

Good Luck

http://www.videocopilot.net/tutorial/assisted_suicide/


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