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Cloud Tank - reflections

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Graham Quince
Cloud Tank - reflections
on Aug 24, 2018 at 1:21:17 pm

I've ended up with a couple of days without any deadlines, work pressures etc... and while walking through a pet store, spotted a "child's first fish tank" reduced. Now, ever since I saw the



I've wanted to try this.

I had lots of fun setting up the tank and playing with the FPS settings on my phone and when I started the light outside was nice and diffuse - then we had a heavy shower followed by brilliant strong sunlight.

Now - I have to stress this was entirely for fun (the journey is more important than the destination)... but I've not really been able to do much with the footage. By the time I'd isolated the paint using Curves and Levels, it was looking pretty over-processed. Which is a really shame because each cloud looked way better than anything I'd ever made with Particle systems.

I'm planning on playing around some more. I have some black cardboard already, so was going to make an enclosure for the phone, but does anyone have any tips or suggestions.

Here's a link so you can see the sort of thing I was getting (and I moved the camera closer after this one, but the rain hit)

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


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Kalleheikki Kannisto
Re: Cloud Tank - reflections
on Aug 24, 2018 at 1:28:34 pm

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


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Graham Quince
Re: Cloud Tank - reflections
on Aug 24, 2018 at 1:32:39 pm

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
http://shiveringcactus.wordpress.com/ - FX blog


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Kalleheikki Kannisto
Re: Cloud Tank - reflections
on Aug 24, 2018 at 1:58:17 pm
Last Edited By Kalleheikki Kannisto on Aug 24, 2018 at 2:15:29 pm

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


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Richard Garabedain
Re: Cloud Tank - reflections
on Aug 24, 2018 at 3:41:19 pm

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


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Steve Bentley
Re: Cloud Tank - reflections
on Aug 24, 2018 at 5:47:07 pm

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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Dave LaRonde
Re: Cloud Tank - reflections
on Aug 24, 2018 at 5:38:51 pm
Last Edited By Dave LaRonde on Aug 24, 2018 at 5:43:16 pm

I started by looking at the youtube video -- they don't call these gents the Slo-Mo Guys for nothing! They have a camera that shoots at an EXTREMELY high frame rate! Then you go and mention "phone". Phones can NOT shoot at extremely high frame rates. In fact, they're a really crummy way to get video.

So how do you propose to shoot at an extremely high frame rate? That's the key. Not to mention the shooting & lighting techniques mentioned above. Plus, it appears that you have to work on the fluid being injected into your tank. Theirs is a lot more opaque than yours.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Graham Quince
Re: Cloud Tank - reflections
on Aug 24, 2018 at 7:03:43 pm

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
http://shiveringcactus.wordpress.com/ - FX blog


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Steve Bentley
Re: Cloud Tank - reflections
on Aug 24, 2018 at 7:31:25 pm

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.



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Andrew Somers
Re: Cloud Tank - reflections
on Aug 25, 2018 at 4:03:09 am

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:

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


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


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Mark Whitney
Re: Cloud Tank - reflections
on Aug 25, 2018 at 7:08:03 am

If it's rabbit holes you be looking for...






and the making of:






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Graham Quince
Re: Cloud Tank - reflections
on Aug 25, 2018 at 8:27:24 am

Wow. Just wow.

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


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Kalleheikki Kannisto
Re: Cloud Tank - reflections
on Aug 25, 2018 at 10:47:24 am

Thanks for the videos. Oh man -- those results are out of this world. I'd be happy with much less. Which is what I would get anyways, since I'm limited to 100fps + Twixtor at this time unless I rent a high-speed camera. Guess I'm gonna have to make this a "weekend project" as well :)

Kalleheikki Kannisto
Senior Graphic Designer


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Graham Quince
Re: Cloud Tank - reflections
on Aug 25, 2018 at 12:12:55 pm

Don’t forgot the waterproof motion control rig.

The shots flying through a tunnel of paint and moving around the vortex are hypnotic.

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


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Graham Quince
Re: Cloud Tank - reflections
on Aug 27, 2018 at 1:24:35 pm

I ordered a couple of inks and they arrived yesterday - so I've had more fun with the water tank. I set it up indoors this time, with a little distance from a clear white wall. I tried a few lights, but didn't have any LED lights to hand with enough power.

I used the ProCam 5 app which gave me more control over the camera.

I did try Steve's suggestion of adding salt to change the density to get billowing earlier, but looks like i didn't add nearly enough.

Here's a brief video I've just put together:







As you'll see, I wasn't draining the tank each time. Maybe I'll get good enough at this to make some stock shots, but for now it's about learning the medium. Also, I forgot each time I had a clean tank to set the focus manually, so the auto focus kept screwing things up! Still, it's a lot cheaper than paying for a high speed camera.

Thanks again for everyone's advice. When I next get a chance, I'm itching to try dual layers and also smoke rings.

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


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Steve Bentley
Re: Cloud Tank - reflections
on Aug 27, 2018 at 3:24:43 pm

Some of those orphans that stream off the orange and take on a life of their own are classic! Very nice.
Watch out for the reflections from ambient light (and you blocking the light) bouncing off the front glass. (we can see you!)
I saw the green screen versions - once you have your matte (the checkerboard) version you don't ever need to make a green screen version. That will only degrade the edges more - the matte is the matte. just archive the footage with an alpha channel for use later.
Re salt: I might not have been clear enough - add the salt (and yes, more than what's in your salt shaker) to some water and then fill the tank to about 1/3. Then put water with no salt the rest of the way up the tank. Its better if the salt water can be colder than the water above it and if you can rig a system where some thin polyetheline plastic can be put on top of the salt water, then the clean water is added on top and then slowly pull the plastic out - this helps the 2 waters not mix ( I sound like a Fremen). You can also try a little camphor in the upper water (pre mix just a pinch) this will lower the surface tension of the upper water and help prevent mixing too.
You can alter "gravity" by either cooling or warming your ink. Warm will tend to make it rise back up in the tank and cold will make it fall faster.
You can also squirt clean water with a second syringe and that can add a "front" for the ink to curl around. If you've ever see time lapse of clouds in the mountains, you know that there is no difference between liquid and air.



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Mark Whitney
Re: Cloud Tank - reflections
on Aug 27, 2018 at 3:37:54 pm

Hey Graham,

That looks really encouraging. If nothing else you can get some interesting organic stuff to use as luma mattes.

The blog link to the Red October was interesting & most I hadn't seen. I actually worked on the miniature shot of the Russian Bearcat just before parachute drop shown. Semi long story but our 4-5 days of high speed bluescreen work were for naught & what you see in the final is the model stuck on a C-Stand arm at the edge of the Salton Sea.


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Graham Quince
Re: Cloud Tank - reflections
on Aug 27, 2018 at 3:59:47 pm

Hi Steve,

You’re quite right about the green screen. I only added in the background to demonstrate that it was keyed out. I’d never export that with green in the background.

I’d fashioned a cardboard surround for the front, with the phone inside and off centre. Didn’t spot until editing that underneath the surround was showing up. I also totally missed that I was creating a line of bubbles on the inside of the glass, each time I a bucket of water in. Eventually spotted it and started wiping it down.

I think I’m also going to have to invest in some lights. And yes, a boat load of salt ☺


Hey Mark,

Wow thank you. I love that movie and that’s a really cool insight. To be honest, I’d assumed that shot was footage of a real plane.

As I mentioned in my blog post, I’m not happy with my final version, but I learned about some features of Element 3D which were new to me. The counter measures were most disappointing (as stills they always liked fine) and probably what started my brain ticking over about cloud tanks.

Graham

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


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Mark Whitney
Re: Cloud Tank - reflections
on Aug 27, 2018 at 5:54:37 pm

Ya, I did a few shows with this group that specialized in miniature work before digital matured. The main guy actually developed a formula to "miniaturize" water come to think of it so that it reacted as if at scale when shot high speed. To say these folk were into detail is putting it mildly. Fun group to work with but sadly no longer with us.


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