Intro to Motion | The Motion Artist's Media


 

The Motion Artist's Media

Eadweard Muybridge was a pioneer in the study of motion using sequential art, one of the mediums we're going to study in this lecture.

The study of physics and natural motion in the world around you is an important stage of the research and planning process for any motion art project. But after you understand the nature of motion, how do you convey it?

The way you choose to depict your motion art is almost as important as how well you convey the motion itself. Your medium and style choices have communication benefits and limitations.

Think about illustration. If an illustrator is attempting to recreate a beautiful flower, should he or she use black charcoal or watercolor paint? The answer depends entirely on what the illustrator wants to communicate to the viewer. If the illustrator wants to show the way the colors of the petals softly transition along the edges, then watercolors are almost certainly the better choice. But to show the way light interacts with the forms, maybe the illustrator should choose charcoal. Is the flower representing serenity or passion? That answer might dictate the way the illustrator makes lines on the paper... or canvas... or wood panel.

The choices you make before the actual motion creation are as crucial to the communication of your work as the decisions of the illustrator. In this lecture, you will learn about the style and medium decisions available to you as a motion artist, and how your choices affect the way your art communicates to your audience. You will also gain an understanding of the mental processes involved with our perception of motion.

In this lecture, you can expect to:

Explore four overarching categories of motion art: motion in a single image, sequential art, low frame rate motion, and full motion video.
Learn about the Cartesian coordinate system.
Explore four techniques for achieving motion on a 2D plane: position, scale, rotation, and distortion.
Learn about techniques for combining motion options, including parallax.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The "obvious action" communication of motion in still images will return in Lecture Three, when we examine the animation benefits of exaggeration.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Don't neglect the importance of the background when trying to avoid ambiguity in your communication of motion.

Streaky directional lines are symbolic communications of speed.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Embrace the constraints of your chosen medium as creative challenges.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Our brains make sequential motion art possible by filling in the "gaps" between the frames.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

You can find more images from Eadweard Muybridge's important and innovative motion studies at www.muybridge.org.

 

 

 

 

 

 

Even conceptual communication has cultural underpinnings. For example, Japanese manga comics have a right to left panel progression, because the written Japanese language is read right to left.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Remember that frame rate motion is understood automatically in the mind, whereas motion in still images and sequential art is deciphered and interpreted.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The animated GIF was invented in 1989 as an enhanced version of Compuserve's Graphical Interchange Format—and it hasn't really changed since!

 

 

 

 

 

 

 

Types of Motion Art

 

Our brains are incredibly good at perceiving motion. It is a skill that served us well as a species attempting to survive in a jungle of hungry beasties. In those situations, being able to quickly recognize motion could mean the difference between catching a meal and being a meal.

Of course, your job as an artist is to manipulate these evolutionary survival traits in order to communicate your ideas. Artists have been doing this for thousands of years. And although it is difficult to classify the outrageously wide range of options, for the most part all motion art falls into one of the four following categories:

 
 
  • Motion in a single image
  • Sequential art
  • Low frame rate motion
  • Full motion video
 
 

Motion in a Single Image

From cave paintings to modern photography, the attempt to capture motion in a still image has been a pursuit of nearly every still artist in history. In its very nature, the still image is missing the primary thing that motion requires: time. In our first lecture, we defined motion as a change in position over time. But an image is timeless, a moment frozen in time forever.

Over the years, many artists have conceived creative ways of showing motion in their work. The Egyptian tomb paintings showed motion by simply having characters and livestock engaged in obvious action, as shown in the below image taken from the tomb of Menna.

Our minds assume all the motions of farming in this image from the tomb of Menna.

The "obvious action" method is by far the simplest way to depict motion in a still image. In early cave paintings, a line drawing of a man with a spear pulled back to throw at a gazelle was enough to show the action of hunting. The renaissance painters often used the obvious action method as well, as shown in the image below from Titian's "Bacchus and Ariadne." The figure leaping from the back of the chariot is obviously either in motion or breaking all the laws of physics. Since we have never seen anyone break the laws of physics by floating in the air, then we make the logical conclusion that the character is in motion. Judging by his pose we can assume he is most likely moving forward and toward the ground.

Another from the tomb of Menna. See if you can identify all the implied motion in this painting. Don't stop with the humans!

Of course, painters were not the only ones who used these methods to show motion. Sculptors used the same mind tricks to make it seem as if their figures were simply paused in time. The implied motion helped establish life within the work.

Attributed to Euphranor: Paris or Perseus, ready to hold forth.

We can replicate this indication of motion in a still image by simply showing an object in a situation or position that is commonly associated with action or motion. Below is a single image showing a ball rolling off the edge of a table. It is nearly impossible to look at that image and interpret it as anything other than a ball in motion. That is because the ball is in a situation that can only be a result of motion. How can it not fall?

Next stop: the floor.

The only issue with trying to depict motion in this way is that the motion can sometimes be ambiguous. Is a character holding up their palm in a "stop" gesture, or are they waving their arm back and forth?

The image below was the same ball as above, only fractions of a second earlier. It was moving too, but the ambiguous placement and the coincidental background line of the blinds make it hard to know for sure.

Rolling or relaxing?

If you are going to attempt to show motion in a single image, the "obvious motion" needs to be exceedingly clear. Otherwise you risk ambiguity in the image.

But there are tricks you can use to help your communication of motion. Artists are incredibly resourceful, and as visual communication grew, they realized they could add elements to their work that could indicate more than just the actual objects they were trying to depict. Adding a halo around a person's head in a painting became visual shorthand to indicate that person was holy or sacred. This small symbol became something that artists could embed in their paintings to help communicate additional meaning.

Similar non-literal visual elements can be added to art to help indicate motion. Something as simple as an arrow can add an implication of motion to an image. For example, the motion lines used in Japanese manga are a symbolic way of stressing speed. No matter how fast we run in real life, we are rarely surrounded by streaky directional lines. But when we see these lines in an image, we understand them as a symbolic way of depicting speed.

In this panel from Takehiko Inoue's Real: Volume 2, note how the motion lines surrounding the runners emphasize their speed. Check out those especially subtle lines in the trees.

Remember that all these symbolic tricks are attempts to overcome the still image's lack of ability to manipulate time. In The Family Circus comic, creator Bill Keane devised a very creative and straightforward way to indicate motion over a period of time. By simply creating a dotted line that trailed behind a running child—punctuated by bursts of dialogue—Keane indicates a path of motion and creates an illusion of passing time in a single panel. This device worked so well that it became one of the most common reoccurring gags in the comic.

In Bil Keane's Family Circus, the dotted line symbolically indicates motion. Click here for an enlarged version.

The symbolic language used to indicate motion is varied and stylized. You can ghost the moving object to make it look like it is burring in a direction. Often cars or people running are illustrated with a small dust cloud behind them to indicate the dust they stirred up as they were moving forward. All of these symbols are simply visual elements that help communicate implied motion in a still image.

Symbols of motion

Orson Welles said, "The enemy of art is the absence of limitations." The limitations of still art empowered artists to invent the creative methods they used to depict motion. So although you have the entire world of creation options at your fingertips, never underestimate what you can successfully communicate with a single still image.

Sequential Art and Comics

We can communicate loads of information with a single image, right? So you would imagine if you simply added a second image, you would just double the amount you could communicate. So let's just try a little experiment.

The orange experiment

If I were to ask you what is happening in the above images, what would you answer? I'm guessing you would say something like: "The orange rolled off the stack of books," or "The orange fell off of the books."

However, if I were to show you either of the two images alone, you would say: "That is an orange on a stack of books," or "That is an orange beside some books." Neither image alone shows any sort of implied action. Each is a still image of a seemingly still object. So why do the two images, side by side, convey motion? Where in these two images do you see the orange roll or fall?

In truth, that motion happens completely in your mind. You are filling in the gaps. The two images are two captured moments in time. Because of the similarities in the images, your mind decides that motion must have happened when you weren't looking, at a moment in time that was not captured. The books are the same, the black background is the same, and the only thing that changed was the orange. So logic fills in the blank. Most likely the orange didn't teleport down there. And although it is completely possible that we're looking at two similar oranges during two entirely different occasions, the close proximity of the two images leads us to believe that not a huge amount of time has elapsed. So our most logical conclusion is the orange must have moved when we weren't looking.

Our logic fills in the gaps in this sequence of images.

This ability to draw logical conclusions about motion has proven very helpful in our evolution. Imagine that you are a Cro-Magnon person running away from a saber toothed tiger. You turn around and see that the tiger is one hundred feet behind you. You run for a few more seconds and turn again to see that the tiger is only fifty feet behind you. You can assume that while you weren't looking the tiger continued to run and has gained on you. Being able to discern that this is the same tiger in two different locations is much more useful than if you had assumed the first tiger is now missing and now you have two tigers to worry about. Hiding under the blanket to make the monsters go away only works if the monsters aren't real.

Being able to understand that things still exists even though you can't see them at that moment is called object permanence. It is a skill that is learned around the age of eight or nine months. The game peek-a-boo becomes a bit more morbid when you realize it relies on the infant believing mommy has disappeared forever.

Poor Gordon! Click here for a full sized version of my comic.

But our development of object permanence is also what allows us to understand that the orange moved when we weren't looking at it, and that the tiger assuredly bound to devour us is the same tiger we saw the first time.

The idea that multiple images could be used to show movement and action over time is by no means new. Many people point to Egyptian cave paintings and Trajan's Column in Rome as early examples of sequential art used to tell a story.

Trajan's Column. Click here to see the sequence play out in the full size image.

The advent of the motion picture also came along as a result of photographic experimentation with motion. Eadweard Muybridge is most well known for his sequential photographic experiments of humans and animals in motion.

In this piece from Eadweard Muybridge, we see an old timey dude running in his underwear ... for science!

Sequential art is an ideal medium for communicating a lot of information efficiently. The combination of graphics and text that can be navigated at the viewers own pace makes for a clear way to give instructions or tell a complicated story. It is no coincidence that the safety information on an airplane is explained with sequential art, not to mention the instructions for putting together that chair you bought at Ikea. It can be a very powerful medium for a motion artist.

In his book Understanding Comics, Scott McCloud explores the many faceted ways comics and sequential art can be used as a form of communicating your art. He explains that comics are a truly interactive media because a large portion of the story is envisioned in the things that are not pictured, in the empty gap between each panel known as the gutter. Comics also differ a bit from other forms of still images, McCloud explains, because we read comic panels in a similar way as we read text, left to right up and down. A single image in a comic often depicts an elongated time period of seconds or even minutes. It is highly recommended that you pick up McCloud's book. It is a wonderful exploration of the art form.

Low Frame Rate Motion

Low frame rate motion relies on similar concepts as sequential art to communicate motion. However, it has one benefit that comics do not, which is the element of time.

In comics and sequential art, time is represented by space. If you move forward in space from one image to another, it is also understood you are moving forward in time. The amount of time is not constant: it can be one second or a million years, but time is innately tied to space. But in the viewer's actual experience of time, each individual image in a comic is frozen.

Not so in low frame rate motion, which we can think of as a very slow version of film or video. In this kind of motion, time is linked to well ... time. The objects occupy the same space, and the motion is understood with the changing of the images, as you can see in the following animation:

Despite the often extremely low frame rate, the succession of images occupying the same space is easily interpreted as motion, as if we are watching something move while rapidly blinking our eyes. It is important to note that the understanding of this motion is something that happens automatically in our minds, where as in still images and sequential art, the motion is something we decipher, interpret, and accept.

You might notice low frame rate motion effects in a photo slide show if two very similar images appear in succession. Our minds connect and smooth over all the things in the image that either don't change or change only slightly. This connection allows us to immediately notice the differences from image to image and interpret those changes as we would in the real world: as motion. Watch as my face and body change in the animation below:

A Greg in motion is a Greg you can believe in!

A common modern use of this is the animated GIF. An animated GIF is an image that has the ability to change into another image after an allotted amount of time. Because GIFs are easy to create, they quickly became overused and abused in the early age of the Internet, as advertisers learned that a flashing banner with a dancing baby got more attention than a still image.

In recent years, GIF art has been used in a variety of Internet memes. Capturing and slightly altering frames from a film or video allows people to create small looping snippets of motion to make a single comment or statement to post on forums, in comment streams, and as status updates. And although a lot of GIF memes end up being crude or rude, many artists have started to mine the medium as a way to explore ideas of minimalistic motion. A simple GIF of a woman blinking, or a flag blowing in the wind, can be amplified by the deathly stillness of the rest of the image. So although GIFs have a very lowbrow origin, don't underestimate their ability to create an impactful piece of art in the right artist's hands.

Photographer Jamie Beck and motion artist Kevin Burg teamed up to create this elegant animated GIF. For an article on their work, click here.

It is easy to assume that low frame rate motion is simply a lower quality version of full frame rate motion (which we will talk about soon). But by manipulating the mind's ability to interpret this motion, you can actually achieve some very artistically satisfying effects that would require a small team to create with full motion video and film. Three frames per second versus 30 means 10 percent of the work to achieve an effect that the viewer will still one hundred percent interpret as motion. True, the animated GIF is not a medium for all forms of visual communication, but don't discount its ability to serve you as a strong and surprising artistic tool.

 

 

 

 

 

 

 

 

 

Movie theater films play at 24 frames per second, and most television and Internet video plays at 30 frames per second.

 

 

 

 

 

Your mind, not your eyes, is responsible for your perception of frame rate motion.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

All motion art is ultimately 2D.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As a motion artist, the restriction of the 2D image plane can be both a challenge and an advantage. In fact, the fake depth of film was the source of many special effects before the CG revolution.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Motion results from forces and occurs as change: change in position, scale, rotation, or distortion.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stay aware of the real world expectations your viewers will bring to their experience of your motion art.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nearly all natural and bodily motion comes more from rotation than from actual change of position.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Create complicated motion with less work through non-central pivot point rotation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Most objects display some sort of distortion in the process of moving, and this is often one of the trickiest (but most important) motions to capture in your art.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

You can make 3D motion on the 2D image plane with optical illusions based on distortion, such as the distortion of internal lines and colors in a shape.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Motion art options rarely appear in isolation; full fledged motion art comes from combining these options.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Don't forget about the manipulation of surface attributes such as color, texture, and transparency.

 

 

 

 

Full Motion Video

Making a video with your cell phone camera doesn't automatically make you a video artist!

Ah, here is why you have been waiting! Yeah yeah, images, comics, GIFs, blah, blah, blah. Film and video—that's the real deal, right? Well, don't get too far ahead of yourself. Modern technology has granted us easy access to the creation of film and video. But just because you can whip out your smart phone and shoot a video doesn't mean you can effectively use it as a tool for communication. And chances are, if you can't communicate well with a still image or sequential art, you won't be able to communicate well with video either. Want proof? Go to YouTube. For every good video, you will find hundreds that are terrible.

Full motion video sprung from the concept that we talked about in the low frame rate section. When similar images are shown in succession, our eyes and mind quickly identify the similarities and differences and interpret the differences as motion. In the late 1800s, motion picture cameras emerged that took advantage of this part of our perception.

Modern cinematic film flashes images in front of you at a rate of 24 images or frames per second. And most television and Internet video is at a frame rate of approximately 30 frames.

You will often hear people attribute our ability to interpret this change as motion to a physical process in our eyes called persistence of vision. Persistence of vision is the process of our eyes briefly holding onto an image even after the image has gone. But although persistence of vision is a real physical occurrence, the theory that it accounts for our interpretation of motion was debunked in 1912. The real reason we perceive a succession of images as motion is more akin to an optical illusion, a misinterpretation by your brain called the "Phi phenomenon." The science behind the Phi phenomenon is complicated, but the important thing to remember is that frame rate motion is perceived because of a mental process in our brain, not a physical occurrence in our eyes. So the next time you hear someone perpetuating the persistence of vision myth, make a motion to explain the truth!

1D, 2D, 3D, and ... 4D?

Even if our brains play tricks on us, we can still define some concrete truths about the physical world. For example, the world you live in exists in the third dimension. That means that to define any point in space you need an origin, or starting point, and three-dimensional coordinates. If I wanted to tell you where my favorite book is, I could guide you by telling you it is about five feet from my left, three feet to my right, and five-and-a-half feet up. It is sitting on a shelf. It is Jumper by Steven Gould, and if you haven't read it ... well, now you know where to find it.

Everything in the third dimension has length, width, and height. Each are labeled in the Cartesian coordinate system as the X, Y, and Z axes. The first dimension is a theoretical straight line. A line only has length, so to describe that line, you only need a single dimension: length. The second dimension is a flat plane. A real world example, although still imperfect, is a piece of paper. It has length and width. I could guide you to any point on that piece of paper by simply giving you two dimensions, such as 3 inches over and 4 inches up. Watch and listen to the following video for a visual explanation of the Cartesian coordinate system:

These first two dimensions are difficult to visualize because everything in our world has three dimensions. Even in the examples above, the line you drew had a very thin width and the paper had a microscopically thin thickness. If you want to explore this concept more thoroughly, I recommend Edwin A. Abbott's classic novella, Flatland.

So what is 4D? Smell, right? 4D is smell? No, it is something that is equally hard to visualize. The fourth dimension is time. Animators, motion artists, and filmmakers adjust and manipulate time just as a painter or sculptor would adjust and manipulate shape. Time is one of the dimensions in which you will manipulate your art. And just as we have the ability to move around in the three dimensions of space, as a motion artist you can move back and forth in time, sculpting it to your needs.

But It's Actually All 2D

So as hard as it is to visualize the Cartesian coordinate system and the way the different dimensions of space interact with each other, the hardest part is to unlearn it. In the end, all of your motion art is 2D anyway.

I know what you are thinking, "Well yeah, traditional animation is 2D but what about Toy Story and all the Pixar movies? Those are 3D."

The artists who made the film may have created the entire film in a virtual 3D environment in which they sculpted and animated the visual elements in the X, Y, and Z coordinates, but when the movie was complete, it was rendered down to a flat series of 2D images that flash in sequence at 24 frames per second. Even the stereoscopic 3D that charges you an extra four dollars at the theater is not really 3D. It is simply two slightly different images being shown to each eye to give the illusion of the third dimension.

If you put your 3D glasses on, these M.C. Escher heads might seem 3D, but that is just an illusion based on offset images presented separately to your left and right eye.

The reason this is so hard to believe is because the illusion is so convincing. In 1895, the film L'arrivée d'un train en gare de La Ciotat (The Arrival of a Train at La Ciotat Station) was released. It was a simple fifty second film of a train pulling in at a train station. But legend has it that the audience screamed and ducked for cover as the train approached the screen. The story was recently re-popularized by the Martin Scorsese movie Hugo (based on the book The Adventures of Hugo Cabret). Although some dispute the validity of the legend, it makes a very clear point: until the invention of the motion picture, all motion we saw was in the third dimension. Film flattened that motion onto a projected screen, and the illusion, although not quite as scary as it was in 1895, still persists today.

Ahh, it's coming right at us! Run!

No matter how much it hurts to admit, all visual art is constrained to the image plane. This is not due to some shortcoming of the art itself, but it is instead a limitation that we face as human beings. That is because our eyes—the part of our body where we take in visual information—are constrained primarily to the front of our heads and very close together. If you are standing in a forest, most likely you will see a scene similar to the one below.

What is behind that clump of trees and leaves on the left? For that matter, what is behind you? Better hope it's not a bear. But you will not know unless you move to the other side of the tree or turn around. That is because everything that comes into your eyes is from, largely, the same perspective. If one of your eyes were on the back of your head, you would likely take in the world in a much different way than you do now. But since your eyes are both in the front, you observe the world as if it were a living 2D image.

Motion on a 2D plane

So now that we know we're working in 2D, how do we achieve motion on that plane? Well, remember those forces we classified and discussed in our first lecture? Forces that cause changes in movement, direction, and geometrical discussion? Those forces are what help us determine our options for making motion, which can come in four big flavors:

 
 
  • Position
  • Scale
  • Rotation
  • Distortion
 
 

Let's take a look at each of these and break down how they work.

Position

The most basic of motion options is movement of position, a change along the X and/or Y axis:

In the above animation, the motion on the 2D image plane is pretty simple. The ball is moving from the left side of the screen to the right side of the screen. But of course we have to take into consideration that we are not used to seeing motion in the world that is not happening in the third dimension. Remember the train? So it is also very easy to convince our eyes that this ball, moving from left to right, is actually a still ball with a moving camera perspective.

The ball is doing nothing different in the above animation than it was in the first example. It is moving from the left side of the screen to the right. But the change in background also changes our understanding of the scene and our brain makes connections to similar motion it has witnessed in the real world.

Scale

Scale is a change in the size of an object. Scale can be either uniform or non-uniform. Uniform scale is when the entire object gets larger or smaller at the same rate. Non-uniform scale is when the shape gets larger or smaller at a different rate along one or more of the axes. Watch the two videos below for examples of uniform and non-uniform scaling:

Uniform scale: when the entire object changes size at the same rate.
Non-uniform scale: when the entire object changes size at a different rate along one or more of the axes.

It is important to notice that rapid scale change is not something we see often in the real world. A tree grows at a very slow rate. In relation to the picture plane, a change in scale is often perceived as an object simply getting closer or farther away. Because of the perspective nature of the third dimension, objects that are far away appear small, and objects that are close appear large. It is part of the inner workings of your mind to recognize that if the saber-toothed tiger is getting larger, it is most likely not growing; it's coming to eat you.

Rotation

Rotation is another way that objects can move on a two dimensional plane. All that is required for an object to rotate is a pivot point, or a source of the rotation. The square in the animation below is rotating while facing the 2D image plane with a center point as its pivot. But just like in the previous examples, this could also be construed as a square that is sitting still while a camera or viewer orbits it.

Is the square doing the rotation or the camera? Try to see it both ways!

An object's pivot point is important in many regards, because nearly all natural motion comes more from rotation than from actual change of position. Let's take your hand as an example. Move your hand around. Wave it in front of your face, pick some stuff up, clap your hands together, and ask yourself "What is the source of this movement?"

The answer, if you haven't figured it out by now, is that your movement comes from the pivot points of your arm parts. You are not moving the position of your hand to wave; you are rotating at your shoulder, elbow, and wrist. The motion of your hand is all the result of the rotation of the parts of your arm. That is why your hand's motion is always in an arc. It is actually very difficult to move the palm of your hand in a perfectly straight line.

You'll be hearing more about arcs very soon.

This effect of a non-central pivot point resulting in arced change in position is something that you can, and should, use to your advantage. For example, the simple animation below was created entirely by rotating a part of the image from a non-centralized pivot point. It is a tool that you can use to create complicated motion with less work.

Getting a "push" on the swing in this animation is actually all about rotating a specific part of the image from a non-centralized pivot point!

The pivot point, or point of origin, is also important for a scale. For example, if the point of origin for a scaling object is at its center point, it appears only to grow. But if it is far away from the center, the scale results in both growth and a change in position, as you can see in the following video:

A pivot point far from the center of an object results in both growth and a position change.

Distortion

Position, scale, and rotation are all pretty easy to spot, but sometimes the way an object changes over time is more difficult to classify. Often these changes are simply a distortion of an object. For example, go to your linen closet and pick up a bath towel by two corners. What shape is it? How would you describe it? Mine is a rectangle. It is pretty much flat with a slight bit of thickness.

I dry my hands on this.

In theory, based on our discussion so far, we could change this object in all sorts of ways. We could change its position in space, or we could rotate it. We could also do things as motion artists that we couldn't do in the real world: scale the towel uniformly to make it look bigger, or scale it non-uniformly to make it stretch. All of these types of manipulation are easy to describe.

But what if we simply let go of the corners of the towel? Does it scale? Well, not really. I guess it also kind of changes position, but it isn't really a rectangle anymore. If you had to describe this motion you would probably say that the towel "crumpled onto the ground."

And then I throw it on the ground.

Here's what happened: the towel distorted. And like it or not most objects display some form of distortion in the process of moving. Even in our previous hand waving example your skin and muscles were contracting and bulging and stretching, all more descriptive ways of saying "distorting."

But as complex as distortion is to describe, it is a motion artist's dream. In the scenes you animate, create, capture, and alter, you have the ability to distort objects more or less then they would in the real world. You are in control. But distortion is a delicate balance. Too little can result in a stiff lifeless motion. Too much, and you might change your object so much it becomes unrecognizable. Consider the examples in the animation below:

Like porridge heat, squashing and stretching is a delicate science.

In relation to the 2D image plane, most three dimensional motion simply becomes distortion. By definition, there is no third dimension on the image plane. So any perceived movement in the third dimension is all an optical illusion in the viewer's head. If you watch the below example of a cube rotating in 3D space, you will completely believe that you are seeing an actual 3D rotation.

But what is actually being displayed on the 2D image plane is simply a distorting shape. The internal colors and lines create the illusion of movement in the third dimension. Our minds read this as three dimensional rotations, but as far as the image plane is concerned, you are simply distorting the shape.

Without internal colors and lines, you lose the illusion of 3D, as you can see in this animation.

Combining Motion Options

But rarely do motion options appear as isolated as we've broken them down here. Much of your motion work is going to be based on mixing these options together.

As we mentioned before, objects close to the camera appear larger, while objects far away from the camera appear smaller. But an object's distance from the camera also affects the way its motion is perceived. Objects that are far away move slower than objects that are close. Our minds understand that if an object is smaller and moving slower, it is probably further away.

This is how depth is faked in two-dimensional scenes. Early Disney films used the illusion to their advantage as a way to give depth to their traditional animated films. When they wanted a scene to feel like the camera was moving, they simply moved things closer to the screen faster, and things farther away from the screen slower. They combined motion based on scale and position. The technique was later used in side scrolling video games. The technique and illusion are commonly referred to as parallax. Here is a video example:

If what's closer is faster and what's farther is slower, you get an illusion of depth—a technique known as parallax.

A combination of change in position, rotation, scale, and distortion allows you, as a motion artist, many different options in creating animated motion. Some animation tools are designed to help you create motion more easily, but often they are simply automated ways of combining the standard manipulation methods.

For example, some animation tools give you the option to animate an object along a path. It is important to note, however, that this is just a simple way of controlling a complex combination of an object's position, rotation, and distortion. This same exact motion could be created by manually moving, rotating, and distorting the object. The tool simply gives you an easier and more intuitive way to control the object's motion.

All of the manipulation methods discussed in this lesson so far give you the ability to manipulate the shape and form of objects. But it is also important to remember that you can animate your object's surface attributes. Changing an object's color, texture, transparency, and lighting information can be a powerful tool as well. Although a practical reason to change an object's color, texture, and transparency may not seem immediately obvious, this can be extremely useful in visual effects. Animated transparency also allows for layering elements and is often used to blend between shots in video editing. And animating lighting can be a strong way of changing a scene's mood and environmental elements.

Many 2D side-scrolling games, such as Braid, use simple rotation, translation, scale, and texture changes to achieve very complex animated characters. Watch this trailer and try to spot all the techniques.

Conclusion

Your job as a motion artist is to work within this 2D image plane in order to create the illusion of the 3D motion that permeates the world in which we live. In the next lesson, we will discuss how you can manipulate the objects and elements of the 2D picture plane to communicate the illusion of motion. You will also learn some rules from the animation pioneers who developed some of the world's earliest believable motion art in the form of the animated cartoon.

Learn about the 12 principles of animation and their application in both 2D and 3D motion art.
Explore how to set up a pose-to-pose animation workflow.
Learn how to use key frames and breakdowns to create clear and communicative animations.
Learn about techniques and options for transitions between animation frames.

Discussion
Share your thoughts and opinions on motion in the Discussion area.

Exercise
Try your hand at your own examples of limited motion mediums and full motion video.