Full Motion Video
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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!
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.
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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.
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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:
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- Position
- Scale
- Rotation
- Distortion
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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.
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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.
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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.
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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.
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."
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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:
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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.
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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.
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.