Cloud Tank – reflections

[Kalleheikki Kannisto]

That link goes to a site which had a nasty pop-up ad attack that got past my Norton security. Please post file somewhere sensible.

Kalleheikki Kannisto
Senior Graphic Designer

[Graham Quince]

Oh sorry about that. I use Mediafire. it’s normally reliable.

Here it is on Google Drive

http://www.YouTube.com/ShiveringCactus – Free FX for amateur films
https://shiveringcactus.wordpress.com/ – FX blog

[Kalleheikki Kannisto]

Yes, that’s better.

To point out the obvious: a phone camera isn’t the ideal camera for such. Apart from quality issues, I suspect you need to be very close to the glass, which gives you reflection image over a large area behind the camera.

I would set this up in a room rather than outside if you have suitable lighting equipment for it. That way you can have a dark room with the lights only on the backdrop and the liquid. Black curtains or board on the reflection side is definitely a plus. perhaps place the camera slightly obliquely so that it doesn’t reflect on the glass. But not so far off axis that it creates a double image through the glass. A camera with a decent zoom would help with this. Also, if the background is REALLY white, it helps alleviate any remaining reflections.

Black background would be a good option as well. Then you would only have to light the tank.

PS. It is a very nice effect indeed. As it happens, I am reading James Gleick’s “Chaos” currently, where he’s talking about turbulences in water and air. Now you got me wanting to try this out…

Kalleheikki Kannisto
Senior Graphic Designer

[Richard Garabedain]

well…for one the camera is really far away..if you cant do it inside then try some polarized sunglasses in front of the camera

[Steve Bentley]

Hey Kal, if you’ve been reading that then you’ll love this – be warned it’s a rabbit hole.
https://www.youtube.com/watch?v=EVbdbVhzcM4

As a veteran of cloud tank shots that I’ve gladly left behind – I much prefer directing particles that for the most part behave and stay in their trailer until called for – I do kind of miss the physical effects we used to do. I think you had to be more inventive to get the shot. Now you are at the mercy of how good the software is.

A few things:

We found that having the injection point mounted to some sort of armature helped quite a bit – the little perturbations that you impart with your shaking hand – I defy anyone to squeeze a syringe without a little shaking – will set up pulses in the previously calm water.

Then if you can, add a solenoid system for the injection. I was amazed how repeatable the clouds were. Not matte repeatable but you could get a look, and then refine with more pressure, quicker squeeze, higher temperature water, lower temperature paint etc. But I know this is for fun so that kind of control might kill the buzz.

Think about the ink as the matte not the background. Light it so that you don’t have the super deep shadows in the folds of ink you want, but enough that with good a good colorspace, you can crush the footage to get rid of the shadows and then you have your matte, or crush the other way and you get the deep darks in the folds of the liquid. Any remaining holes in the matte you can garbage matte.

Pick a color of paint that easily warps its Hue to other colors.

Make a drainage system. The biggest buzz kill is to have to clean the darn thing after every take. With a drain/refill system you can do a shot every 5 minutes.

We made this grid thing that we lowered into the water – kind of like the divider thing inside a case of wine that keeps all the bottles separate. It allowed the currents to calm down so much faster and then you slowly remove it and let the currents do a final settle. Kind of like a “straightener” in a fountain water jet. Get that that water still!

Indoor lights are better (due to heat) and some IR film in between the lights and tank help to reduce the convection that the lights will set up due to heat. Use LEDs if your high speed can handle them because there is no warm up needed – keep them off until just before the shot. Some LED systems flicker to change brightness and some are all-on all the time. Choose the latter. Pick as “blue” a white as you can handle – less infrared energy.

The other cool thing you can do with LEDS is time them the flicker to the camera’s frame rate, and you then can do a front light/back light flicker that prints to every other frame and if the frame rate is fast enough , every other frame is your matte (back lit) and alternate frames are your beauty lighting (front lit).

Use a stable base – remember jurassic park? Every time you move, you are imparting subsonics into the water and that starts it moving.

Try a salt water layer or a cold water layer or both- if you put in a cold salt solution first then let warm distilled water run down the side the of the tank, to gently fill. The paint will hit that inversion layer and fan out like its hit something – but the “barrier” is clear, so its very apocalyptic.

Adding glycerine or salt or heavier soluble salts to the water can dramatically change the density, which can get those billows happening sooner out of the nozzle and prevent contamination from taking place too soon so the cloud holds together longer. Using another liquid can have some unique effects – think how oil and water just wont mix. I’m not sure what liquid to recommend, we used to do this with (gulp) Carbon Tetrachloride and TriChloretheline before anyone knew it was toxic. But it prevented any mixing and the edges were crazy sharp. (DON’T DO THIS!) But vodka might work or some other high proof alcohol. Keep the space well ventilated!

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[Graham Quince]

Thank you everyone, some great advice.

Steve – sounds like you had it down to a fine art. Currently my wife is hoping this is a weekend fad, but I really want to try out all your build suggestions ☺

Dave – The phone I have can shoot 240fps at 1080p, I also rewatch the video and spotted they used water soluble ink. I’d got the wrong end of the stick and grabbed paint. I wonder if that makes a difference.

If I do get anything usable, I’ll share it here.

http://www.YouTube.com/ShiveringCactus – Free FX for amateur films
https://shiveringcactus.wordpress.com/ – FX blog

[Steve Bentley]

It depends on the cloud look you want. Personally I like the look of vinyl paint, but acrylic works too(with acrylic extending medium). I find water based ink starts to dissolve in the water too quick so the cloud starts to blur right quick. I’m also not a fan of black ink. It works great for stock footage but you don’t see the subtle density differences or the shadows in the folds – it just ends up looking like a matte of itself.

[Andrew Somers]

Tip 1) Duvetyne is your friend. https://www.filmtools.com/expendables/fabric/duvetyne.html

Tip 2) No lights on the camera side of the front glass, unless they are attached to the glass with no light leaking out away from the tank.

Tip 3) Douglas Trumbull/Scott Squires used multiple water densities (salt and fresh, and I seem to remember Ammonia being used per an AmCin magazine I can’t find at the moment). Link of Scott’s recollections:

https://effectscorner.blogspot.com/2009/02/cloud-tank-effect.html

Andrew Somers
VFX & Title Supervisor
https://www.GeneralTitles.com

[Mark Whitney]

If it’s rabbit holes you be looking for…

https://www.youtube.com/watch?v=3CRIEmzaW2s
and the making of:
https://www.youtube.com/watch?v=LETHMzJCJ0s

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[Graham Quince]

Wow. Just wow.

http://www.YouTube.com/ShiveringCactus – Free FX for amateur films
https://shiveringcactus.wordpress.com/ – FX blog