Making Animal Collective’s Animated Slipmat

Insights into the design of stroboscopic discs

Animal Collective recently released their highly anticipated tenth studio album, Painting With. I was honoured to be invited by Domino Record Co. to design an animated slipmat packaged with the Deluxe LP edition.

The animation works by first placing the slipmat on a spinning turntable in a dark room, then flashing it with a strobe light set to a specific frequency.

The final slipmat design.

That’s it! No screens, no shutters. As the light is strobing, you can look on with your own two eyes to perceive the animation. There’s even a strobe light built into the official Painting With iOS app to make things easier, but any controllable strobe or strobe app will do.

This slipmat is both a physical object and an animated sequence. The fact that you can hold an animation in your hand and manipulate it while it’s playing is pretty cool, and I’m thrilled that so many Animal Collective fans have already had a chance to experience this in person.

But what the hell is it? How does it work?

I’m going to break it apart and show you step by step what exactly brings this slipmat to life.

Origins and classification

Example of a Stroboscopic Disc, invented by Simon von Stampfer.

The Animal Collective slipmat has its origins in some of the earliest forms of pre-cinema animation. Devices such as the Stroboscope, Phenakistoscope, and Zoopraxiscope all utilise a similar flat, circular layout, and only differ slightly in their execution.

Due to this close aesthetic and functional relationship, it would in fact be more accurate to classify the slipmat as a stroboscopic disc.

Foundations of the moving image

To understand how stroboscopic discs display animation, we really need to deconstruct how we perceive moving images in the first place.

The animator’s old faithful; the bouncing ball.

The animation above is made up of 18 individual drawings shown at a rate of 12 frames per second. The sequence is shown too fast for our brain to process them as still images, so we instead perceive it as movement. There are many ways of achieving this illusion, from simple devices like flip books, to the more sophisticated equipment found in film projectors.

On a strip of film, every frame of a movie or animation is situated next to one another in order. The first frame is the beginning of the movie, the last frame is the end, so as well as providing visual information, a strip of film also represents a timeline.

Unlike the first bouncing ball animation above which was a digital animation, a filmstrip can’t instantaneously replace one frame with the next. It’s physical and in a continuous flow, meaning that each frame is only ever in the right position for a small fraction of time.

A simplified example of how the same animation might behave as a filmstrip. Watch this video for a more accurate and in-depth explanation.

As film is run through a projector, the shuttle syncs each frame with the rate of the shutter. This causes the lamp to shine light through the film only when each frame is correctly aligned with the lens, not when it’s transitioning between frames. For a traditional 35mm film, there are 24 frames projected per second. If you were to watch the raw film strip roll by at that speed, you would see nothing but a blur. However, the mechanism of the projector ensures your eyes will only ever see frames when they’re aligned, resulting in the illusion of movement.

Below is an example of the same concept, but this time the sequence isn’t in one long line but instead fanned out to form a circle. This is the general layout of a stroboscopic disc.

The basic principle of how a stroboscopic disc works.

How stroboscopic discs work

Just like a filmstrip, stroboscopic discs require a way of distinguishing between correctly aligned frames and those which are passing by.

A Phenakistoscope being used in front of a mirror.

Instead of using a shuttle and shutter, early devices like the Phenakistoscope and Stroboscope had slits cut into the disc corresponding with the number of frames of animation. The viewer uses the device by peering through the slits while spinning the disc in front of a mirror.

The image above helps illustrate how viewers will only see a glimpse of the animation in the reflection of the mirror when one of the slits passes in front of their eyes, thus synchronising the animation.

Another way of achieving the same goal is to use a strobe light. If played in a darkened room, the viewer won’t be able to see the sequence until it is lit by the strobe. If the strobe light is set to the correct frequency, the images will be visible to the user when they are aligned in the correct position. This is the method I’ve used for the Animal Collective slipmat.

(WARNING: this video features strobing light) — An example of the strobe being used for the Animal Collective slipmat. This is one of my tests to get the strobe rate right for the app — View on Instagram

What’s interesting to note is that when using either of these the methods, you’re not exposing only one frame of animation at a time, but the entire disc.

Herein lies the crucial point of difference between stroboscopic discs and screen-based animation; stroboscopic discs allow you to see every phase of an animated sequence simultaneously.

All 18 frames of animation can be seen simultaneously in this final stroboscopic disc design.

This drastically changes the relationship between spatial and temporal information, and is at the heart of what makes stroboscopic discs such an interesting medium to work with.

Techniques for designing a stroboscopic disc

Now that we’ve covered the basics of how stroboscopic discs work, it’s time to take control of it’s unique characteristics and see how they can be used for experimental and innovative animations.

Frames as a representation of both space and time

The above image is a still snapshot of our bouncing ball stroboscopic disc. If, when watching the animation, you happen to be watching the ball in the middle frame, then this frame could be considered the Present in the timeline of the animation. Considering that the disc spins clockwise, the panel immediately to its right is the Future as it is the next image in the timeline, and the panel immediately to the left is the Past as it was the previous image shown.

In screen-based animation, you only ever see one frame at any given moment, which removes any sense of a spatial relationship between frames, but in stroboscopic discs, there is a direct relationship between space and time. This characteristic can be utilised in a number of ways. One of the simplest is the ability to create constant movement in both clockwise and anticlockwise directions.

Creating lateral movement

Every example so far has been concerned with synchronising the number of frames of animation with the playback of the disc. The bouncing ball was 18 frames long and was laid out on a disc with 18 segments. This synchronisation forces the animation to be stationary in the sense that after a full revolution, the loop will repeat itself starting from the same location.

So what happens when the sequence doesn’t have the same number of frames as the disc? What would a sequence 17 or 19 frames long do if laid out on a disc composed of 18 segments?

The answer is actually quite simple; they drift clockwise and anticlockwise.

Think of it this way. When a sequence is synchronised with the disc, it restarts precisely when the disc reaches the original frame. To use the terminology introduced above, the sequence began in the Present, and restarts in the Present. As we’ve already established, there is a direct relationship between spatial and temporal information, so if the sequence is synchronised in time, it will also stay in the same location.

The bouncing ball animation illustrates this clearly by continuously bouncing in one spot.

Stationary — The sequence has the same number of frames as the disc.

Now lets add one frame to the sequence, taking it to a total of 19 frames. This time when the disc is spun, it completes a full revolution in 18 frames, one frame before the animation has a chance to finish. Instead of the sequence restarting in the Present, the disc continues to spin one more frame, causing the sequence to restart one segment to the left, or in the Past.

Again, this is shown clearly in the example below as each bounce drifts clockwise by one frame.

Clockwise movement — The sequence has more frames than the disc.

The opposite is true when removing one frame for a total sequence length of 17 frames. The animation finishes one frame earlier than it takes for the disc to complete a full revolution, restarting one frame to the right, in the Future.

A sequence of fewer frames than the disc therefore creates anticlockwise movement.

Anticlockwise movement — the sequence has fewer frames than the disc.

Once you have a grasp of this trick, it becomes easier to push it further. If you were to increase or decrease the length of the sequence by two or three frames, you’d end up with faster clockwise or anticlockwise movement.

It’s worth noting that the terms Past, Present and Future in this context are entirely relative and don’t hold up to much scrutiny, but I find them to be useful in making sense of what effect spatial and temporal decisions will have on one another when designing stroboscopic discs.

Parallax effects

I was able to put these techniques to good use in the Animal Collective slipmat. You might not have noticed it at first, but there are three main layers moving in independent directions.

The primary actions (the dripping water and the walking characters) were animated in sync with the disc. This, as we all know by now, causes them to be stationary. These are the busiest elements in the sequence with the most amount of animation, so I didn’t want to overdo it by also giving them clockwise or anticlockwise movement.

Stationary foreground.

Having decided upon the characters being stationary, it was clear that the platform beneath their feet needed to be moving for their walking to be convincing. As explained in the previous examples, this can be achieved by giving the floor one fewer frame than the disc for it to spin anticlockwise.

Anticlockwise walking platform/stairs.

Finally to give the animation a sense of depth, it was important to have the background moving independently from the foreground. I could have made it go anticlockwise at the same speed as the stairs, or reduced the sequence length even further to make it rotate faster, but I instead opted to have it rotate in a clockwise direction. It doesn’t meet convention, but it adds to the surreal vibe of the animation.

Clockwise background.

When these three layers are combined, they create a sort of parallax effect and do a great job of messing with your perception of depth and space.

All three movements combined.

Extending runtime

Unlike film, stroboscopic discs can only fit a small and finite number of frames. This drastically reduces the possible length of sequences. The stroboscopic disc of the bouncing ball was 18 frames in total. It used a frame rate of 10 frames per second, which means it has a total runtime of 1.8 seconds.

However, there is a handy trick you can use to show sequences which appear to run for much longer.

Instead of the sequence being a perfect loop and starting back at the beginning, you can animate an object to finish its sequence at the location where another object started. If done seamlessly, there is no way of telling where one sequence ended and another began, so the viewer instead believes they are watching a much longer, continuous sequence.

I have included an example from an earlier project of mine called the Embroidered Zoetrope which also utilised stroboscopic discs. Each disc has 14 frames of animation playing at 12 frames per second, resulting in a max runtime of 1.16 seconds.

‘Wriggling’ — Embroidered Zoetrope

As you can see, by carefully directing the motion so that one sequence replaces another, you can seemingly extend the runtime. If you train your eye on one of the worms emerging from the outer edge and follow it to the centre, their journey will appear to take roughly 8 seconds. That’s nearly 7 times the runtime of the disc itself.

The Animal Collective slipmat was designed to coincide with their song ‘Recycling’ so it seemed natural to try and elaborate on this theme by morphing different elements into one another over time. It’d be impossible to communicate this idea in 1.8 seconds, so I had to rely upon this technique to extend the sequence.

As you watch the video below, take note of the long, continuous path taken by the water.

The water starts out as a droplet and drips down, morphing into the torso of the character. The torso then pops out and falls down, becoming part of the stairs, which eventually melts back into a droplet, finally returning to the outer ring of water.

Much like the wriggling worms, this sequence wouldn’t have been possible without seamlessly blending different sequences together.

Unconventional animation formats such as zoetropes, phonotropes and stroboscopic discs are having a resurgence, seemingly sparked by technologies like 3D printing and scanning which further blur the the divide between digital and analogue.

I love working with these formats because they challenge so many standards of film theory and language. Some of the restrictions seem extreme, like the direct relationship between space and time, however they also result in new and inventive ways of presenting animated sequences.

Designing this animated slipmat was such an exciting and challenging project. It was a pleasure being able to experiment with this medium in collaboration with Animal Collective and the greats folks at Domino Recording Co.

If you’re hungry to find more animation and art using similar techniques, I highly recommend checking out Jim Le Fevre’s blog, Phonotropia, or you can keep up to date with my work by following me on Tumblr and Instagram.