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Learn about keyframes and timing in 3D animation. Understand the principles of animation and how to use Maya tools to set and adjust keyframes. Explore the importance of timing and how it affects the overall motion and expressiveness of your animation.
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Introduction to 3D Art and Animation Lesson C (week 3): Introduction to 3D Animation
Animation: Keyframes and Timing Traditional, Hand-Drawn Animation:Draw master “Keyframes” for main action poses, then draw in-between poses. 24 frames per second (24 fps) means each second of animation has 24 drawings. “On twos” means only making 12 drawings to display twice each to fill the 24 fps. NOTE: Disney animation is 30 fps, feature film VFX & video games are 60fps, Virtual Reality is between 90-120 fps. In computer animation we set Keyframes (red lines in the Maya Timeline) and the program interpolates movement between those Keyframes. Often, we start by setting Keyframes as much as 10-20 frames apart to “block out” the big timing and poses, and then add more Keyframes between them so final spacing is more like 3-5 frames apart.
Animation: Keyframes and Timing A Keyframe = a Pose, usually containing Move, Rotation, and/or Scale information. In Mayaa Keyframe (a thin red line in the timeline) contains this specific TRANSFORM info: Move, Rotate, Scale, as seen in the Channel Box. TIMING: The more tics/frames between Keyframes, the slower the motion between those two poses. The closer two keyframes are to each other on the Timeline, the faster the movement between those two poses. Timing should be varied. Break an action into three parts, like a ball throw: • Anticipation (pulling the arm back, turning the body in preparation to throw) • Action (actually throwing the ball), • Follow-through (the motion of the arm-- and the entire body!-- after the ball has left the hand, to complete the motion and re-establish balance). Consider these possible variations between these three motion parts, often used in animated film: a slow Anticipation could allow the viewer to focus on the thing about to act, a fast Action can express weight, and a slow Follow-through can help the viewer feel the power of the moment when the action happened. What happens if you vary timing differently? In a game, for example, enemy characters often have a long anticipation, but player characters often have 1-2 frames of anticipation before the action plays. Why is this difference important? Consider the varied timing in these punches (often, the action is skipped!), from the show “One Punch Man”: https://www.youtube.com/watch?v=L6cvVnApcS8
12 Principles of Animation (Disney) The 12 Principles of Animation were developed by members of the original Disney animation team back in the 1920s and 30s to guide their process toward ever more expressive and believable movement. Often, the intention is not to represent pure reality, but to create express and believable motion. Often animators use very strange movement to get results that are more expressive and “real” to the viewer. The Disney 12 (we will cover 6 today): • Squash and Stretch • Anticipation • Staging • Straight Ahead Action and Pose to Pose • Follow Through and Overlapping Action • Ease In and Ease Out • Arc • Secondary Action • Timing • Exaggeration • Solid drawing • Appeal
3D Animation: Basic Maya Tools 1 The Timeline Scrubber:LeftClickDrag to change the current time. Start at frame 1. When a Keyframe is set it appears as a red line. You can RightClick a Keyframe on the timeline to Cut or Copy and Paste it. Three ways to set Keyframes on the Timeline: • Set Timeline Scrubber to frame 1, select the object, and in the Channel Box select a Channel (try Y rotation), then RightClick to choose Set Keyframe. Note that a red line is created in the Timeline at frame 1. This red line contains the Y-rotation value you set, and is only visible while the object is selected. • Turn on Auto Keyframe Toggle (located to the left of playback controls). Scrub to a new time. Make a change to the object. If you rotate on the Y-axis, because there is already a Keyframe for that channel (and Auto Keyframe Toggle is on), a new Keyframe is made to hold the new transform of Y-rotation. You can change any existing Keyframe by scrubbing to that tem and Transforming the object again. • Choose a time and hit [S] to set Keyframes on ALL channels. Now, with all Channels keyed, ANY Transforms on ANY Channels at other times will set Keyframes.
3D Animation: Basic Maya Tools 2 Adjusting Timeline Keyframes: • Copy and Paste: select a keyframe by clicking directly to its right, hit [s] to be sure all channels are keyed, RightClick to choose Copy. Select a new frame, RightClickto choose Paste > Paste. Can also Cut and Delete. • Move a frame or a selection of frames in the Timeline: hold [Shift] and LeftClick drag to select a range of keyframes (the range will be red). Click and drag the little yellow triangles at the center of the range to move them, or the outer triangles to scale the distance/timing between them. This also allows us to copy/paste or delete multiple frames at once. • Copy all keyframes to another object: Select 1st object, Edit> Keyes > Copy Keyes. Select 2nd object at desired 1st frame, Edit > Keyes > Paste Keys. • Bookending: Set two keyframes with the same value at different times, in order to create a pause in the animation, or an Animated Hold.
3D Animation: Basic Maya Tools 3 Playback: If you hit the Play button, the animation may seem very fast. By default, Maya is set to “Play Every Frame.” This is a useful setting for complex VFX simulation, but for animation we want “24 fps.” Change this setting now by clicking animation settings (little running-person icon in the lower right corner). How much time? The Timeline Scrubber shows about 100 Keyframes by default. We often want to see more or less time, and our film can be as long as we want, regardless of how much of it we are showing at any given time in the Timeline. See the pairs of settings to either side of the Timeline? One is for the start or end of the visible timeline, and the other is for the start or end of your entire film. Change these number and hit [Return] to see the effect. NOTE: We are running Maya at 24 fps, but please THINK in terms of 30 frames per second. So, for a relaxed walk cycle that might take 3 seconds to cross a room, you would budget 90 frames (which, playing back or rendered at 24 fps, will slow down your walk a bit, letting your animation breath).
EXERCISE 1: Bouncing Ball Part A • SETUP: Create a Sphere object from the Polygon shelf. In the Persp viewport, Move [W] it up so it stands on the grid and over to the left side. Now we animate: • With the sphere selected and the Timeslider at frame 1, go to the Channel Box, select all three Translate channel names (X, Y, and Z), RightClickHold and choose “Set Key.” This captures the position information at that time, • Turn on the Auto Keyframe Toggle button to the left of the playback tools. Now, if we change the time and then move the object, a new keyframe will be set at the new time for the new location. • Set the Timeslider to time 100. Move the ball sideways all the way to the right side of the Persp grid. A Keyframe should be created at frame 100 for the new position (remember: Keyframes are only visible when the object is selected). • Set Timeslider to frame 20. In Channel Box, select all 3 Translate channels, RightClickHold and choose “Set Key.” This records the down position. Repeat at frames 40, 60, and 80. • At frame 10, Move [W] the sphere upward (on the green Y-axis) to create the lift. Repeat at frames 30, 50, and 70 (but not at 90), each a little less high than the last. • Hit play to view your animation so far. You may notice that it does not yet feel like bouncing. What does the motion feel like instead? To help you understand the motion, go to the Animation module, and turn on Visualize > Create Editable Motion Trails or Visualize > Ghost Selected (naturally, sphere must be selected). • Save your file!: YourName_BouncingBall.mb
EXERCISE 1: Bouncing Ball Notes Note the spacing of the drawings here for this 2D animation. We don’t need as many Keyframes for most motions in 3D, but as an exercise (in a different scene) you can try settings Keyframes on every frame to imitate this spacing, and observe the sense of force and weight created!
Animation: The Graph Editor THE GRAPH EDITORvisualizes animation as separate tracks to make quick changes to Keyframe timing (horizontal spacing) and value (height). Open Window > Animation > Graph Editor. Select a keyframed object in the Viewport or Outliner. Select a track in the Graph Editor to see motion as a line: keyframes and interpolation curves. With practice, these curves will read like object motion to you! • [Alt]+MiddleMouse to pan Graph Editor view, [Alt]+RightMouse to zoom. • MOVE A SINGLE KEYFRAME OR BEZIER HANDLE: choose “Move Nearest Picked Key” in upper right, LeftClickDrag around a Keyframe or Handle, MiddleClickDrag to move it. Or select one or more keyframes and enter numbers into the upper “Stats” boxes. • MOVE MANY KEYFRAMES: In the upper right, choose the “Region Tool” and select around multiple Keyframes to move them at the same time. This tool also supports non-uniform scaling to move Keyframes closer or further apart, to scale timing/value. • CREATE A KEYFRAME: Upper right, choose “Insert Keys Tool” and MiddleClick on the curve to add a new keyframe. Move the keyframe to the desired time (horizontally) and value (vertically). Delete a Keyframe: select around it and hit [Delete] key. • Bezier Handles are lines sticking out of each Keyframe. They define the interpolation curve moving through the Keyframe. Two handles together make a Tangent. LeftClickDrag to move a Handle and change the curve. To move handles independently, first select Keyframe/s and hit Break Tangents. To Switch Tangents select one or more Keyframesand hit atangent preset choice at the top-center of the Graph Editor. Linear Tangent makes flat or sharp transitions. Professional animators like Step Tangents to see poses they have created with no interpolation, before they deal with transitions.
EXERCISE 1: Bouncing Ball Part B Let’s make the bounce more bouncy! In your bouncing sphere file, Open Windows > Animation Editors > Graph Editor: • REMOVE EASE-IN/EASE-OUT: Select the translation track for horizontal movement (either X or Z). Notice the line is not a straight, but instead an “S-Curve,” showing how the object speeds up at the start and slows down at the end. Maya applies this “Ease-In / Ease-Out” by default. To get a straight line, select around and delete all the middle Keyframes,then select the two ends and hit Linear Tangent (diagonal icon, center-top of the Graph Editor). • MAKE BOUNCES SHARP: LeftClick the Y-Translation (movement up and down) track. See green curve that represents the Y-motion of your sphere, including the rounded bottoms that SHOULD be sharp points in order to have a sense of sharp impact. LeftClickDrag around these bottom keyframes to select them, and then click the Linear Tangent button (center-top of Graph Editor). Play your animation– it should already appear more sharp, less rubbery, at the bottom of each bounce! • MAKE EVEN SHARPER: Bring each pair of bottom Bezier Handles closer together. By default, these handles are locked; moving one up brings the other down. Re-select all the bottom Keyframes, hit Break Tangents. You can then LeftClickDrag around a Bezier Handle and MiddleClickDrag to move it. To fix odd curves above, try moving the top Keyframes. • RE-TIME: All bounces are evenly timed, but lower bounces should be faster. Use Move Nearest Picked Key or the Region Tool (upper right) to make lower bounces take less time (bring their impacts closer together) and the taller bounces take more time (move their impacts further apart) • Save your file!
Animation: Copy From One Object To Another COPY AND PASTE TOOLS:Tocopy keys from one object to another: Be sure your animated and target objects both have keyframes at frame 1, and the timeslider (timeline, time scrubber) is at frame 1: To copy ALL keys from one object to another: select the animated object, and in the main menu Edit > Keys > Copy. Select the target object, Edit > Keys > Paste. Try copying your sphere animation onto a polygon box! To copy only specific tracks from one object to another, use the Graph Editor: Select the animated object, select the desired track/s and around desired keys. Go to the Graph Editor menu and chooseEdit > Copy. Select the target object, Select the tracks, Graph Editor menu Edit > Paste. NOTE:pasted keyframesstart at the location of the time scrubber, so be sure to set that to the time you want the animation to start!
Animation: Parenting PARENTING: You can set up a hierarchy between objects so that when the “Parent” one is Transformed (move/rotate/scale), the other (“Child”) “inherits” the same Transform. • To set up Parenting, select the intended child object (or children), select the intended parent object last, then hit [P]. • To remove/break the parenting hierarchy, select the children and hit [Shift]+[P]. NOTE: In 3D, a parent can have many children, but a child can only have one parent. If object A is a child of object B, and you parent A to object C, A automatically loses its connection to B. If an object deforms wildly when rotated, its parent has a non-uniform scale. The solution is to (a) break the hierarchy ([Shift]+[P]), (b) Modify/Freeze Transforms on the parent, and then (c) re-parent the hierarchy.
Animation: Bookending for Control Bookending is where we set two identical (or nearly identical) keyframes a short or long distance apart on the timeline, thus protecting the space between from changes outside (a controlled pause!) or protecting the outside from changes made between (a controlled action!). The easiest way to accomplish Bookending is to set a keyframe and then copy/paste that keyframe later in the timeline.
EXERCISE 2: Make a Box Come Alive! • In a new file, start with a Box, move up and to the left like we did with the sphere, and set keyframes by selecting the translate tracks in the Channel box and hitting Key Selected. Turn on Auto Keyframe Toggle, go to frame 100, and move the box to the right side. • At frame 50, Key Selected the Translate channels, then in the TimesliderCut and Paste that Keyframe to frames 30 and 60, in order to Bookend a pause halfway through the motion! NOTE: if the bookend appears wiggle, go to the Graph Editor and set those bookend keys to the Linear Tangent. • At frame 32, Key Selected the Rotation channels. Copy and Paste that keyframe to frame 58. You have now bookended a rotation range, so you can now make any rotation between those frames, in the movement pause, and it will not affect the time before and after the pause. Make your box look nervously to either side! • Now add bouncing to the motion before and after the pause: use Key Selected on the Y-translate channel to make your down poses at 10, 20, 70, 80, and 90. Then lift the box to desired bounce heights at frames 5, 15, 25, 65, 76, 85, and 95. In the Graph Editor, select the down poses and set Tangents to Linear! • Play your animation, and enjoy as your box comes to life! Save your file.
EXERCISE 3: Deformers! Deformers are tools for dynamically changing your mesh, and can be used both as part of a Modeling process (like bending a cylinder to make an arch, and then delete history to “bake” that deformation into the object) or in Animation, to set keys on the deformation! Our main deformers can be found in the Animation module, under Deform > Nonlinear: Bend, Flare, Sine, Squash, Twist, and Wave. TRY THIS: Create a new polygon object • Keep object selected and apply the “Squash” Nonlinear Deformer. Note a new gizmo appears inside and around the mesh. The deformer is a separate object that you now have selected. • Open the Channel Box Inputs for this Deformer and try changing the Factor value to squash and stretch the form. • If you Key Selected this Channel, you can then animate squash and stretch on your timeline! NOW TRY THIS: Select your “living box” from the previous exercise. • At frame 1, add a Squash Nonlinear Deformer to the Box. • Parent the Deformer to the box so that it follows the box’s motion (select the Deformer, [Shift]+ select the box, hit [P]). Now Animate: • At top of each bounce arc, & at frames 31 & 59, Key Selected to capture Factor=0 shape. • At bottom of each bounce, set Factor to around -.1 for a slight squash (creates a sense of “impact”), and at 1-2 frames before and after each squash set the Factor = .2 (or more) for a stretch (creates a heightened sense of motion). You can also emphasize the look-around part of your animation with some squash and stretch. For more realistic motion, keep these changes small. For more cartoony motion, make them bigger, for more exaggerated motion!
Animation: Clean-Up Cleaning Up Bad Animation: “Bad Animation” is motion that feels unintentionally choppy, awkward, rubbery, broken. A simple solution to choppy animation is to go into the Graph Editor and remove extra Keyframes (select and delete). Sometimes TANGENTS (how animation moves through a Keyframe) need to be adjusted to fix curves. You can change the Tangent on a selected Keyframe by clicking the Tangent buttons in the top bar (often just set them to Linear), or work on them in the Graph: select a Keyframe, select around the bezier handle, and MiddleMouse move it to remove a bad dip on the graph that might make the motion jerky. Rubbery animation is where the timing feels too consistent– no variation in speed so there is no sense of force and weight. Change the spacing of your keyframes to change the timing between them (easier in the Graph Editor). Editable Motion Trails and Ghosting: In the Animation Module, in the Visualize menu, you can find multiple tools to help you understand your motion in a selected object. A Motion Trail is a line that shows your object path through space, and Ghosting is a 3D version of “onion skinning” – a tool to understand motion by seeing previous and following frames displayed lighter around the current frame, like a 2D animator looking through multiple pages of drawings on a lightbox. Hide these tools in the Viewport before playblasting
Homework #3, 1/5: Camera Motion Open your real-room space from your homework. Create a new Camera from the Create menu. Hit [d] to move the pivot from the center to the bottom, so that any rotation feels like the camera is on a tripod (or like a head on shoulders); much more believable/natural than a camera rotating from its middle. Have at least two Viewports open: one to look through the camera (switch to your camera view under the Panel viewport menu), and one to see the entire space (usually Top view). At frame 1, select the Translate (move) and Rotation Channels in the Channel box, RightClick and choose Set Keys. Turn on Auto Keyframe Toggle, change the time and then change the position [w] and/or orientation [e] of the camera. These changes will be recorded as a new keyframe! Create 10-20 seconds (300-600 frames) of animation, moving the camera through your room space.
Homework #3, 2/5: Camera Bookending If you are moving the camera at every Keyframe, it might feel a bit like a rollercoaster. For real control over your camera motion, and to make your audience less dizzy, consider Bookending to pause and look at specific parts of the room. Remember, Bookending is when you set two keyframes at different times that are exactly or nearly identical (by copying and pasting them in the timeline), so that the motion pauses between them, allowing a sense of focus or thinking. For the camera, consider choosing a few places in your room you want the audience to see, and at each location pause the camera motion (a little motion is OK, but keep the camera mostly steady) so that the audience can really see what you are showing them in that place.
Homework #3, 3/5: Haunted Room Animate the various cabinets, drawers, and objects in your room! Make them wiggle, shake, swing, and generally move in a haunted manner! You do not need to make them move constantly– choose when each moves, based on when the camera will look at them. Also, use parenting on multi-part objects, like a cabinet with drawers; parent the drawers to the cabinet so you can animate the cabinet and have the drawers follow it, and still animate the drawers individually (see slide 12 from this presentation on Parenting). ANIMATED FILM PRE-PRODUCTION PROCESS: Normally a 3D filmmaker would: • Type a list of the intended actions and interactions in your film. • Draw a storyboard of shots to best communicate the emotional beats of those actions. • Build a primitive set • Animate the camera to match the storyboard shots and shot list timing (reproduce the angle and framing of the storyboard in 3D). • Block out basic poses and timing (rough animate) of actor proxies in the scene. • Perform test renders and revise the overall timing of the camera and characters before adding in final elements and animating in detail.
Homework #3, 4/5: Force and Weight If something falls, it needs to fall fast in order to feel like it has weight. Often a drop should only take 3-10 frames. “Anticipation” is motion that draws our eyes to the object just before it moves, so that we will actually see the action, even if it is fast. An object on a shelf, for example, can rock back and forth a bit before it falls. In particular, it should rock backwards before it falls forward. “Anticipation” is usually small movement in the opposite direction as the main action. “Follow Through” helps to sell the weight of the object by showing what happens after the action. An object that falls should not just stop when it hits the floor– it should bounce at least a little bit. The height of the bounce, and how much it rotates, will help to communicate if the object is light or heavy. Similarly, for a cabinet door that is meant to swing shut, first Anticipate by rotating about 5-10 degrees backwards (10-20 frames), then swing shut quickly (about 10 frames), then bounce back open 5-10 degrees (a few frames for the follow-through), then stop/settle in the closed position. “Ease In and Ease Out” are automatically applied to objects in 3D animation, often where we don’t want them. To make an object fall believably, we don’t want it starting and ending slow. In the Graph Editor, set those movement keyframes tangents to Linear (diagonal line) or Fast (steep slope)!
Homework #3, 5/5: Playblasting (vs Rendering) Rendering is the process of outputting files with full animation, surfacing (lights and textures), and effects (particles, simulation, etc). Rendering is time consuming– you can expect a single frame of a film to take between seconds and minutes to render, depending on the number of lights, effects, and scene complexity. Animators need to create faster visualizations of our work to view and revise, and so Maya offers Playblasting: a quick video output of the Viewport display: • Set the Timeline to the desired range to show your film. • Hide elements you do not want included in the Playblast. • RightClick on the Timeline, find Playblast at the bottom, and click the Option box next to it. Toward the bottom of the options, turn on “Save to File” and hit [Browse] to choose a name and location (like the desktop). • Hit [Playblast] to create the output video (.AVI by default). Note that everything in the Viewport will render. If you have lights in your scene, you can hit [7] in your Viewport to display that lighting. You can also use the Viewport Show menu to turn off elements you do not want included in your Playblast, like Grids and Editable Motion Trails.