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Unbelievable Waterslide Compositing Walkthrough

I really enjoyed the healthy discussion this video generated. From a guy that’s done a lot of compositing, I can tell you it’s definitely faked. This might not be so obvious though, so I thought it might be interesting to walk through how I think they put this together. The guys that made this were able to do such a fantastic job, in part, by making some really simple, smart decisions about how they went about shooting. In this post I will walk you through the compositing process and how these decisions culminated in a video believable enough to make anyone second guess their initial reaction to it.

First off, for those unfamiliar, compositing is the art of combining several pieces of separately shot footage to appear as if they are one piece of footage. It’s a relatively simple process that involves cutting out bits and pieces of different clips and creatively reassembling them–layering them, moving them around, offsetting them through time, scaling, rotating, blending them, attaching blurs, color and level changes, etc. to make everything appear as if it were shot in camera.

In this video there are three separate shots.

1.) The Master Shot: The dude sliding down the slide and flying through the air
2.) The Splash Shot: The dude landing in the pool and making a big splash
3.) The Victory Shot: The dude climbing out of the pool and being congratulated by his buddies.

The Shooting Process:

First, they create their three pieces of footage. In the first piece, they filmed this guy sliding down the slide. In the raw footage, this probably looked like a regular dude sliding down a giant water slide. He didn’t go nearly as far as in the finished video. At the end of this piece of footage, the camera pans over to the empty pool and holds for a beat before zooming in on it.

Second, they film the guy jumping into the pool from a stunt platform. The framing of this shot matches the end of the master shot.

Third, they shoot the guy emerging victoriously from the water. This shot also starts framed up to match the end of the master shot and then zooms in to get in on the action.

The Composite:

In Adobe After Effects or your other compositing program of choice, the compositor starts with the master shot. The dude is extracted to his own separate layer and his movement down the slide is artificially sped up by manually animating his position to give the impression of great momentum. His flight through the air is also accelerated and the distance he travels exaggerated by again animating his position and scaling him down into the distance. The holes left behind from cutting the dude out of the original footage are filled with the same footage at a different point in time, where the dude is not visible.
Picture 1
Good compositing decisions: First, the camera is very stable for this part of the shot, which I think is intentional–a stable shot is easier to work on because camera movements have to be accounted for and are less of a factor here. The camera is zoomed all the way out making the dude very small. Also, from this angle, we see very little of the dude on the second half of the slide. The less detail we see of him, the more convincingly he is manipulated. When he takes off from the slide, his flight is backdropped by the blown out sky, which makes cutting him out and extending his flight easier. In addition, you’ll notice when he flies into the air, the camera pans up to avoid showing where he really lands, likely on some sort of airbag. This avoids a tricky cleanup process at a spot in the video where the camera is moving quite a bit.

In shot number 2, the pool is cut out, deleting the stunt platform and rest of the background. It is then tracked to the movement of the camera from the master shot using tracking software, and laid on top. The splash is timed up perfectly with the dude making his killer landing.
Picture 3
Good compositing decisions: The landing is seen from far away, zoomed all the way out. Blending the master and splash shots isn’t going to look perfect, no matter how skilled the compositor. The smaller it is in the frame, the more convincing it will look.

Finally, as the camera zooms in on the dude getting out of the pool, they perform a simple fade to shot 3. The dude emerges victoriously from the water and is congratulated by his buddies.
Picture 4
Good compositing decisions: The zoom. It helps hide the fade between shots. You’ll notice the water splashing from his landing stops at a certain point; the transition happens here. It’s almost impossible to tell. The dude is conveniently submerged at this point. You’ll also notice from earlier, his buddies at the landing zone are positioned far away, well outside the final framing. This guarantees they will not be on frame for the fade.

So there you have it. Tack on some convincing sound effects and you’ve got yourself a pretty believable waterslide.

11 comments
  1. rob says: August 5, 200912:19 am

    Well done sir.

    stolen from somethingawful, but eric deserves it

  2. adam says: August 5, 20098:55 am

    outstanding work!

    I think this little problem demonstrates a serious multi-disciplinary problem solving ability we have here at jtb.

    everyone used their own experience to debunk this video. crazy IT detective work from rob, some engineering insight from myself, and the badass compositing walkthrough from eric.

    fuckin smooth.

  3. kyle says: August 5, 200911:00 am

    excellent breakdown Eric! JUICE!

  4. choof says: August 5, 200911:13 am

    Well done!

    This video has created quite the discussion on Juice and everyone responded in true Juice fashion. I love it.

  5. hoffmangler says: August 6, 20092:01 am

    Awesome. Curiosity and quick google search brought me here. Great walk through! Thanks for making it.

  6. eric says: August 6, 20091:33 pm

    Glad you guys enjoyed it!

  7. andrewembassy says: August 12, 20092:24 am

    You say “you’ll notice when he flies into the air, the camera pans up to avoid showing where he really lands, likely on some sort of airbag.” but I’m pretty sure from about 10ft down the slide he’s animated – you can see the stuntman arrested by a rope in this video: http://www.youtube.com/watch?v=sDh73yAYkl0

  8. andrewembassy says: August 12, 20092:24 am

    Aside from that, great walkthrough!

  9. eric says: August 12, 200910:00 am

    You are totally right. Thanks for pointing that out!

  10. T-Dub says: October 27, 200910:10 pm

    Hey Eric – a couple of dents in the grass around the pool, even better, a couple of pairs of upturned feet & legs sticking out of the ground from earlier “range finders” may have got under your BS-detector! WDYR?

  11. eric says: October 28, 200911:13 am

    T-Dub–I’m not sure what you’re talking about.

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