Animating Introduction What is a time warp curve? > Example of a time warp
Introduction
Learn what animation is, what you can animate and about the different animation techniques used.What is animation?
Learn how animation is defined and used in AliasStudio.Animating an object means that one or more characteristics or attributes of the object change over time. For example, if you have designed a car and want to see it drive down a road, you must animate its position over time. At time 1, the car may be in front of a house, and at time 50, at a street corner, 10 blocks down the street. In the animation system, you might say that at time 1 the car has an X translation of 0 units, and at time 50 it has an X translation of 10 units (that is, it has moved to a position of 10 units in the X direction). The X translation, in this example, is an attribute of the car that can be animated: we call it an animation parameter.
There are a number of ways to animate in AliasStudio. Many of our users use the animation tools to present final concept models. For example, you can show the assembly of your model or you can display your new model moving though a scene. The animation and photorealistic rendering capabilities create images convincing enough to be reproduced directly into print, video or interactive media.
The animation process is to model, animate, fine tune, and to finally render your animated scene.
What can you animate?
Learn about different levels of animation available in AliasStudio.An object generally has many attributes, or animation parameters, that can be animated. In AliasStudio, a directed acyclic graph node has ten attributes that can be animated: the X, Y, and Z translation, rotation and scale attributes, and also the visibility.
Other types of objects have different animation parameters. For example, a camera's angle of view can be animated, and a light can have its color or intensity animated. An object or other item that has at least one animation parameter or attribute that can be animated is called an animatable item.
AliasStudio offers three different levels of animation
Basic workflow for manually creating an animation
Learn the process of modeling, animating, fine tuning, and finally rendering your animated scene.AliasStudio provides two types of automatic animation, where you plug in parameters and AliasStudio creates the animation, as well as manual, freeform animation.
In AliasStudio, manually creating animation involves establishing a timeline, then varying one or more properties of objects (for example, position or color) over time.
To apply the workflow
- Create the model.
- Decide how long you want the animation to be and create the necessary number of time frames in AliasStudio.
- Use basic techniques to vary the scene through the length of the animation:
- Place objects you want to animate, including the camera, where you want them, and with the values you want, at each point in the timeline, then mark those frames as keyframes.
or
- Establish motion paths for objects to move along through time.
For more advanced animation, AliasStudio is capable of varying almost every property of an object or shader along the timeline, not just position.
- Decide how the objects should transition from frame to frame.
More advanced animation can use the Action window, expressions (mathematical formulas describing relationships between time and object properties), and constraints, to create more realistic and automated effects.
- Preview or render the animation.
Parameters
Objects have many parameters that can be animated. Examples are the objects X,Y, and Z positions, rotations, scaling, and visibility.
Different types of objects have different animation parameters. For example, you can animate a camera's field of view, and the color and intensity of the light.
In AliasStudio, you control which parameters of an object are animated using the Param Control window.
What happens when an item is animated?
Learn how a channel describes how its animation parameter can change values over time.When an animation parameter of an item is animated, a channel is created which belongs solely to that animation parameter. The channel describes how its animation parameter changes values over time. When you view a model at different times, the channel is responsible for telling the animation parameter that it now has a different value.
To illustrate: in the car example above, at time 1 the channel tells the animation parameter it has a value of 0. At time 50, the channel tells the animation parameter to assume a value of 10.
An object is animated if at least one of its animation parameters has a channel. In AliasStudio, a channel is created for an animation parameter by using one of the many animation tools, such as Animation > Keyframe > Set keyframe. If you later decide to remove the animation, you can use Delete > Animation > Delete channels
to remove the channel of animation.
How does the channel know which values the animation parameter should assume at different times?
In the simplest case, a channel evaluates a two-dimensional curve, which plots time against value. These two-dimensional curves are called parameter curve actions. The channel tells the action at what time to evaluate, and the action produces an evaluation value.
> Example
Actions are often created when a channel is created. What the action looks like depends on the animation tool that was used to create the channel. Using the car example, you can describe the car's animation using Animation > Keyframe > Set keyframe. When you begin, the X Translate animation parameter has no associated channel.
Position the car at 0 units on the X-axis, and set a keyframe at time 1.
Since the X Translate animation parameter was not previously animated, a channel is created for it. The channel needs an action to tell it what values to use, and so a parameter curve action is created that has only one keyframe at time 1. Now move the car into position at 10 units on the X-axis, and set a keyframe at time 50.
Since the X Translate animation parameter is already animated, you do not have to create its channel. The channel tells the action to insert a second keyframe at time 50. The action is now a curve defined between the times 1 and 50.
How can I tell if something is animated?
Learn how to quickly identify if something is animated in your model.To see whether an animation parameter has a channel, look at the LOCAL parameters for the animated item in the parameter control window (Animation > Editors > Param control). An animated parameter has a white slanted box next to its name.
What is a parameter curve action and a motion path action?
Learn more about actions and timewarps.There are two types of actions in AliasStudio: parameter curve action and motion path action. The parameter curve action is a two-dimensional plot of time versus value. A motion path action is simply a reference to a 3D NURBS curve. It is evaluated in the following way: the channel gives a percentage value to the motion path action. The motion path action uses this percentage to determine the 3D point that corresponds to that percentage along the curve. This 3D coordinate (X, Y, Z) is returned to the channel. The channel then extracts one of these components (X, Y, or Z), and uses this value as the value for the channel.
Usually a channel is not animated by a single motion path action, but also has a parameter curve action to specify the animation's timing along the motion path action (Animation > Tools > Set motion
; see Create a motion path animation). In this case, there is no longer a simple relationship of one channel to one action. The channel uses two actions to determine what values to tell its animation parameter to assume.
In both these cases, the channel is animated by a base action, and each additional action applied to the channel is called a time warp. This ability for a channel to use many actions is called a one-to-many relationship, because one channel uses many actions to determine what values its animation parameter should assume.
What is a many-to-one relationship?
Having many channels use the same action is a many-to-one relationship. Since there is both a one-to-many (for example, one channel using several actions) and a many-to-one (for example, several channels using one action) relationship between channels and actions, the combined relationship is actually many-to-many. That is, any number of actions can be associated with any number of channels. The many-to-many relationship between channels and actions provides a greater degree of flexibility in creating your animations.
If a channel uses more than one action, then the channel has an expand channel button next to its name in the Action Window. If you press this button, you see the list of actions that a channel uses.
To see which channels use an action, you can select the action and choose Curve Tools > Show instance in the Action Window.
> Summary
The three concepts in the animation system are:
In the Action Window, the relationship between an animation parameter and its channel is made implicitly by using the same name for both.
> Example
The animation parameter named X Translate is animated by a channel named X Translate. In the Action Window, if an animation parameter is not animated by a channel, the animation parameter name is listed in light grey. If on the other hand, the animation parameter is animated by a channel, then the animation parameter is listed in red (X parameters), green (Y parameters), blue (Z parameters), or black (all others).
See Animation > Editors > Action window, Edit > Edit expression for information on Expressions.
Instead of using actions, an animation parameter may be animated by an expression channel. Expressions can be entered by double-clicking next to the animation parameter name in the Timeview Window, or by selecting an animation parameter and choosing Edit > Edit expression from the Action Window.
What happens when you animate a camera on a curve?
Learn more about the three camera components: camera eye, camera view, and camera up vector.
Geometry in a scene cannot be animated using the Animation > Tools > Autofly
function.
The camera is animated to travel along any NURBS curve.
Camera eye
The camera eye can be considered the camera unit itself, which travels along the motion path to which it is assigned. The motion path determines the position of the camera at any given time in relation to the scene. For example, the design of the motion path lets you move the camera closer to or further away from an object in the scene. To visualize, think of yourself walking along with a camera taking pictures: the route you follow would be the motion path.
Camera view
The camera view can be considered the focus point of the camera - where the camera is looking at any given time. If the camera view is not assigned to a motion path of its own, then the view is always directly in front of the camera. Think of yourself walking through a scene without ever pivoting your head, your view is always directly ahead of your body. By assigning the view to a motion path of its own, you can change the view point of the camera at any time in relation to the camera position.
Camera up vector
The camera up vector can be considered the current angle of the camera at any given time in relation to the camera eye. The camera up vector is the direction from the camera's eye to the camera's up. If the camera's up is not assigned a motion path of its own, the camera remains parallel to the path that the eye has been assigned to at all times. By assigning the camera up to an independent motion path, the camera can be pivoted to any angle up to 360 degrees. This can be likened to a camera on a tripod except that the tripod could pivot a full 360 degrees.
At least one curve is needed to use Autofly. If only one curve is used, it must be the motion path for the camera eye. The camera view then remains directly in front of the camera throughout the animation.This might be exactly what you want. If not, and you want to control the camera view throughout the animation, you need at least two motion path curves.
Can I reuse animation on another channel?
Learn how actions are reuseable.The Action Window has tools to make an action reusable by more than one channel. This means that the actions are not owned by a channel. They can be renamed to any name, independent of any channel with which they may currently be associated. Actions can also be shared by more than one channel (Curve Tools > Paste Instance in the Action Window).
In the example above, imagine you want to use the car's motion for a bicycle going down the road next to the car. You can use Curve Tools > Paste instance in the Action Window to associate the same action used by the X Translate channel for the car to be used by the X Translate channel of the bicycle as well. Now the car and the bicycle animate together. The advantage of using the same action for both channels is that if you edit the action, then the motion for both vehicles changes.
> Example
If you want the car and the bicycle to stop at a house along the way at time 20, and then start moving to the street corner at time 30, you can add two keyframes to the single action, and the animation is modified for both bicycle and car.
What is inverse kinematics?
Learn more about the process and workflow of IK animation.You can create the illusion of life by using the skeleton and inverse kinematics animation tools in AliasStudio. The essence of character animation is timing and motion.
Build a skeleton by creating and editing joints and bones. After you've created all the joints and bones that make up a skeleton for your character, you'll want to move the skeleton around and put it in various poses.
There are two basic ways to pose a joint chain: forward kinematics and inverse kinematics.
With forward kinematics, when you pose a joint chain you have a specify the rotations of each joint individually, starting from the parent joint on down to all the joints below.
With inverse kinematics, when you pose a joint chain all you have to do is tell the lowest joint chain's hierarchy where you want it to be, and all the joints above it will rotate automatically. Inverse kinematics offers a very intuitive way to pose a joint chain because it enables goal-directed posing. When you reach for an object, you don't think about how you are going to rotate your shoulder, your elbow, and so on. You just think about where the object is that you want to reach, and your body automatically does the rest. That's how inverse kinematics works, too.
To pose a joint chain with inverse kinematics you need to add some special tools to a skeleton. These tools are called inverse kinematics (IK) handles. An IK handle enables you to pose a joint chain intuitively.
An IK handle begins at a joint chain's parent joint and can end at any joint below the parent joint. For example, for each leg you could create an IK handle that controls the joint chain beginning at the hip joint and ending at the ankle joint.
You can select the IK handle where it ends at the ankle joint and move the chain with it in the same way that you would think about moving your own ankle.
In addition to posing a skeleton, IK handles also play an important role in the animation of the skeleton. The movement of a chain between the keyframes of an animation is also automatically solved by the chains IK handles.
IK handles figures out how to rotate and move all the joints in the chain for you by applying an inverse kinematics solver. The IK solver is the motor intelligence behind and IK handle.
You can animate a skeleton, but such an animation would show only the timing and motion of a character lacking form and shape. The next step is to bind the character's model to the character's skeleton so that the skeleton can control the model's actions.
Use Animation > IK > New skeleton
to create the skeleton, then Animation > IK > Add IK handle
, Animation > Tools > Create constraint
, and Animation > Keyframe > Set keyframe
or Animation > Keyframe > Auto keyframe
to animate your character in its rotation scale and translation parameters.
Create hierarchical geometry for the character independently from the animation and use Animation > Editors > Skeletons
to turn DAG nodes in the hierarchy into joint DAG nodes. Then use Animation > Edit > Overlay skeleton
to overlay the corresponding joint nodes in the model.
What is a time warp curve?
Learn how time warp curves work.A time warp curve is an animation curve (or a action) that is applied to a channel (the animation of a parameter of an item), and modifies the times at which the other actions in the channel are evaluated.
A channel of an item is usually animated by one animation curve, the base action of the channel. If a time warp curve is applied to the channel, then the channel is now animated by two actions. The time warp action modifies how the base action of the channel is evaluated.
You can apply any number of time warp curves to a channel, and each successive time warp curve modifies the timing of the curve directly below it.
How does a time warp work
The time warp curve changes the timing of a channel by mapping the old time of an animation on the Y-axis to the new absolute time on the X-axis. Another way to look at this is that at a given time on the X-axis, the time warp curve is evaluated to a value on the Y-axis, which is a new time. The time is used as the time at which to evaluate the next action in the channel to which the time warp is applied.
Example of a time warp
As seen in the following diagram, a channel is animated by a base action with the time warp curve time warp #1 applied to the base action and the curve timewarp #2 applied to the curve timewarp #1.
In this example, the channel is evaluated at the time 5.
- First, evaluate the last action in the channel, which is timewarp #2, at time 5. Notice that it evaluates to 12.
- Use the new time and evaluate the next curve in the channel, which is timewarp #1 at time 12, and see that it is evaluates to 8.5.
- Use this new time and evaluate the first and final curves in the channel, which is the base action, and it evaluates to 21. Therefore, the value of the channel at time 5 is 21.
When you create time warps curves, they have a default out-of-range type of identity (from the Action Window' Disp Tools > show infinity menu). This means that before the first keyframe and after the last keyframe of the time warp curve, the time warp curve does not alter or warp the timing of the actions below it.
If many time warp curves are applied to a channel, it is often difficult to fine-tune special areas of the animation in the channel. When you are satisfied with the general animation of a channel with its time warps, you can use Curve Tools > use result found in the Animation > Editors > Action window
|
Autodesk www.autodesk.com aliasstudio.docs@mail.autodesk.com |
