Maya Tutorial pdf

upwards, leaves the cargo box in the new location, and rotates back to its original position.

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Planning an animation for an IK system

Now that the mechanical arm and cargo box are fully set up for animation it's a simple matter to pose
the arm and set keyframes. Prior to setting any keyframes you should take a few moments to plan the
action for the scene.

Planning the action usually involves sketching a simple storyboard, and writing out a brief timeline for the
action for each component. In this lesson we've provided a simple version for you. The basic premise for the action is as follows:

 The cargo box is positioned directly in front of the mechanical arm.

 The mechanical arm extends, and positions the cargo magnet to be directly touching the top of
the cargo box.

 The mechanical arm extends upwards, lifting the cargo box, and rotates to the side.

 The mechanical arm lowers the box, placing it in a new position.

 The mechanical arm extends upwards, leaves the cargo box in the new location, and rotates back
to its original position.
The table below breaks down the action indicating what action occurs for each object at the specified
keyframes.

Frame Mechanical                                    Arm Cargo Box
1                               Collapsed position                                Initial position
30                             Vertically extended position                    Initial position
60                           Vertically lowered so that cargomagnet
                                 is positioned on top ofcargo box            Initial position

80                 Vertically lifted to extendedposition
                                 withcargo box                                     Cargo box lifted with mechanical arm
100 SwivelBase rotated along with arm to side   Cargo box repositioned alongwith   mechanical arm
120                   Vertically lowered along with cargo box to second positionabove surface
                                                                                           Cargo box is lowered along with mechanical arm to second
position
140                       Vertically lifted to extende position                Second position
160                      SwivelBase rotated with arm to
                                                                                              original position
                                                                                               Second position
180                     Collapsed position                                             Second position

To pose the mechanical arm you select either the ArmControl or SwivelBase nodes and set a keyframe depending on which component you want to pose:
 ArmControl controls the movement of the mechanical arm.
 SwivelBase controls the rotation of the arm.
 CargoBox's position is based on the parent constraint weights.

p218

Applying parent constraints on an IK system

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Simplifying the display of a hierarchy

The number of nodes in the IK system's hierarchy at this point may appear a bit overwhelming, but it
allows the posing of the mechanical arm to be efficient and effective. You can simplify the display of the
nodes by collapsing portions of the hierarchy.

To collapse the display of the hierarchy

1. In the Hypergraph, right-click on joint1, and choose Collapse from the pop-up menu.
The child nodes below joint1 disappear simplifying the display of the hierarchy. The small
arrowhead on the corner of the joint1 node indicates that a hierarchy exists below joint1. If you
later need to view or select these nodes you can expand them again.

2. Collapse the ArmControl and IKHandle nodes.

The display of the hierarchy is simplified as shown below.

The IK system is now rigged and ready for animation.

Applying parent constraints on an IK system

To animate the cargo box so that it is picked up by the mechanical arm you need a method of
constraining the cargo box to the mechanical arm so that it moves with the arm at specific times in the
animation. This is accomplished using a parent constraint.

When a parent constraint is applied to an object, the constrained object behaves as if it were a child
node of the constraining object.

An object can have multiple constraints applied to it. The influence each constraint has on the object
can be changed by modifying the weight attribute for the parent constraint. The weight attribute is an
animatable parameter and can be set to be on or off at specific frames.

In this lesson, the cargo box is constrained to both the ArmControl and the Platform on the floor. By
animating the weight attributes for these two parent constraints, the cargo box will move from one
location to another depending on which constraint is influencing it at specific times in the animation.

To set up the parent constraints you need to position the constrained object at the locations where the
influence will begin or end, and then set the parent constraints.

To set parent constraints for the cargo box
1. In the side view menu, select Shading > Smooth Shade All.
2. In the side view menu, select Panels > Perspective > persp.
3. In the Hypergraph, select ArmControl.
4. In the ChannelBox, set the Translate Y and Z values as follows:
o Translate Y: -9
o Translate Z: 0
The arm is repositioned so that the cargo magnet is directly above the cargo box as shown below. Track,
tumble, or dolly the view if required so you can see the mechanical arm unobstructed.

5. In the Hypergraph, with ArmControl still selected, shift-select the CargoBox node.
The order of selection is important when you apply constraints. You must select the constraining
object first, and the item to be constrained second.

6. In the main menu, select Constrain > Parent > .

7. In the Parent Constraint Options window, do the following:
o Select Edit > Reset Settings to set the tool to its default settings.
o Click the Add button.
CargoBox is constrained to ControlArm. A new constraint node has been created below the
CargoBox node in the Hypergraph. If you reposition the mechanical arm, CargoBox moves with it
because of the constraint that is now applied.

8. In the Hypergraph, select only SwivelBase.

9. In the ChannelBox, set the Rotate Y value for SwivelBase as follows:
o Rotate Y: -100

The mechanical arm and the cargo box are positioned as shown below.

10. In the Hypergraph, select Platform and then shift-select the CargoBox node.

11.In the main menu, select Constrain > Parent.
CargoBox is constrained to Platform. This is the second constraint for the CargoBox.

12. In the Hypergraph, select only CargoBox.

13.In the ChannelBox, view the parent constraints for CargoBox.

CargoBox has two parent constraints applied to it: Arm Control and Platform. In the ChannelBox,
the numerical settings beside ArmControl W0 and Platform W1 represent the influence weight each
parent constraint has on CargoBox. At this point, each influence weight is set to a value of 1. If
you move the mechanical arm, the cargo box will move somewhere between its first and second
position. This occurs because each constraint has equal influence on the cargo box at this point.
Before you can animate the objects in the scene, you also need to reset the default weight values for
each constraint, so that one parent constraint has full influence on CargoBox when the other does not.

To set the weighting for the parent constraints
1. In the Hypergraph, select only CargoBox.
2. In the ChannelBox, set the following:
o Platform W1: 0
3. Select only SwivelBase.
4. In the ChannelBox, set the Rotate Y value to 0.
The mechanical arm and cargo box are rotated back.
5. In the Hypergraph, select only CargoBox.
6. In the main menu, select Constrain > Set Rest Position.
Setting a rest position for CargoBox sets a position for the cargo box when no constraints are
acting upon it. If the rest position is not set, CargoBox will be repositioned to the second
constraint position.
7. In the ChannelBox, set the following:

o ArmControl W0: 0
At this point, both parent constraints are set to have no influence on the cargo box because their
weight attributes are set to zero. When you animate the components in the scene, the weight
attributes for the parent constraints will be set and keyframed depending on which constraining
object (Arm or Platform) is required to have full influence.

In the next steps, you plan the action for animation of the IK system.

The mechanical arm moves with a limited range of motion.

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9. In the Channel Box, observe the numbers that display in the Translate Y and Z channels.
When the arm is articulated to a compressed pose, the translation values are roughly as follows:
o Translate Y: -13
o Translate Z: -13
These minimum and maximum values will be used in the steps that follow as the minimum and
maximum translation limits for the ArmControl.

To set translation limits for the Arm Control
1. In the Hypergraph, select the ArmControl node.
2. Open the Attribute Editor (Window > Attribute Editor or click on the Show/Hide Attribute Editor
icon on the Status Line).

The Attribute Editor displays the nodes associated with Arm Control.
3. In the Attribute Editor, click the ArmControl tab.
If the ArmControl tab is not visible, use the left and right scrolls arrows to scroll the view sideways
to view it.

4. In the Attribute Editor, expand the Limit Information attributes, and then the Translate
attributes.

5. In the Translate attributes, click the Trans Limit Y and Z check boxes to undim the numerical

boxes and then set the following values:
o Trans Limit Y (Min): -13
o Trans Limit Y (Max): 7.5
o Trans Limit Z (Min): -13
o Trans Limit Z (Max): 1

6. Hide the Attribute Editor.
7. Select ArmControl.
8. In the side view, move ArmControl to test the range of movement for the IK system.

The mechanical arm moves with a limited range of motion.

ensure only the SwivelBase node is selected.

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1. In the Hypergraph, ensure only the SwivelBase node is selected.
2. In the view, select Panels > Orthographic > top.
3. In the view, select Shading > Smooth Shade All.
4. Dolly the top view so you can fully view the mechanical arm as shown below.

5. Using the ChannelBox, rotate SwivelBase by typing 45 in the Rotate Y channel and pressing Enter.

SwivelBase rotates in the view but the mechanical arm does not rotate. You first might think
something is wrong because SwivelBase and all of the arm's skeletons and surfaces are parented
into the same hierarchy.

Note

You may sometimes discover that something doesn't work in the manner you originally anticipated
when setting up an IK system. When this occurs, it's useful to stop and diagnose why something is
working the way it is (or not working the way it should). In that way you can retrace your actions to
determine where the problem resides.

ArmControl and IK Handle are not parented into the SwivelBase hierarchy. Because ArmControl and IK
Handle control the movements of the mechanical arm, they must be parented into the SwivelBase
hierarchy in order for the arm to rotate when SwivelBase is rotated.

To parent the IK Handle into the skeleton hierarchy

1. In the Hypergraph, select the SwivelBase node.
2. In the ChannelBox, reset the Rotate Y channel for SwivelBase to 0.
Setting any previous transformations to zero is necessary before parenting the IK Handle beneath
SwivelBase in the hierarchy.
3. Unselect the SwivelBase node before performing the following steps.
4. In the Hypergraph menu, select View > Frame All.
The Hypergraph displays all the nodes for the scene.
5. In the Hypergraph, shift-select the nodes named ikHandle1, ArmControl, and SwivelBase.
The order of selection is important. You want to shift-select the items that will be the child nodes
first, and then shift-select the item that will be the parent node last.

6. In the main menu, select Edit > Parent (Hotkey p).
In the Hypergraph, IKHandle and ArmControl are now child nodes for the SwivelBase node in the
skeleton hierarchy.

7. In the Hypergraph, select only SwivelBase.

8. Using the ChannelBox, set Rotate Y for SwivelBase to 45.

When SwivelBase is rotated, the mechanical arm rotates because of its relationship within the
hierarchy.
9. Reset the Rotate Y value for SwivelBase back to 0.
Finally, you want to limit how far Arm Control can translate away from the base of the model so the arm
does not extend to a fully straightened position.

To determine the settings for the translation limits you need to examine the position of the mechanical
arm in various positions while simultaneously viewing the translation values in the ChannelBox.

To determine translation limits for the Arm Control
1. In the Hypergraph, select ArmControl.
2. Ensure the Channel Box is open so you can view the translate channels for ArmControl.
3. In the view, select Panels > Orthographic > side.
4. Dolly the side view so you can fully view the mechanical arm.
5. Select the Move Tool.
6. In the side view, press the middle mouse button and drag the mouse diagonally until the
mechanical arm is fully extended as shown below.

7. In the Channel Box, observe the number that displays in the Translate Y and Z channels.
When the arm is diagonally articulated above the cargo box, it is almost fully extended when the
translation values are roughly as follows:
o Translate Y: 7.5
o Translate Z: 1
8. In the side view, press the middle mouse button and drag the mouse in a diagonally until the
mechanical arm is almost fully compressed as shown below.

possible to move ArmControl

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Limiting the range of motion of an IK system

It's possible to move ArmControl so that the mechanical arm fully extends to a straight position or orients
itself to other positions that you don't necessarily want.

You can limit the range of motion of the arm to ensure that the IK system poses in a predictable manner.
In the following section, you limit the motion for the IK system as follows:

Lock the translation of the control object (ArmControl) so that it can only move in Y and Z. By
locking the X channel so it cannot be selected or modified, the arm will not be able to move from
side to side.
Lock the rotations on the swiveling base for the arm so it only rotates about its Y axis, and not
about its X or Z axes.
Limit the translations for the Arm Control so the mechanical arm cannot fully extend to a
straightened position.

To lock the Translate X channel for ArmControl
1. In the Hypergraph, select the ArmControl node.
2. Open the Channel Box to view the transform channels for ArmControl.
3. Set all Translate or Rotate channels to 0, if they are not already.
4. In the Channel Box, select the Translate X channel by clicking on its name.
5. Right click on the word Translate X.
A drop-down menu appears.
6. From the drop-down menu, choose Lock Selected.

The numerical field for Translate X is dimmed indicating that the channel is locked. If you try to
move ArmControl in X, it will not be possible unless you unlock the Translate X channel.

To lock the Rotate X and Z channels for SwivelBase
1. In the Hypergraph, select only the SwivelBase node.
2. Open the Channel Box to view the rotation channels for SwivelBase.
3. Set all Translate or Rotate channels to 0, if they are not already.
4. In the Channel Box, select the Rotate X and Rotate Z channels by control-clicking on their
names.

5. Right click on either of the selected names.
A drop-down menu appears.
6. From the drop-down menu, select Lock Selected.

To confirm that the Rotate X & Z channels are locked

1. In the Hypergraph, ensure only the SwivelBase node is selected.
2. In the view, select Panels > Orthographic > top.
3. In the view, select Shading > Smooth Shade All.
4. Dolly the top view so you can fully view the mechanical arm as shown below.
5. Using the ChannelBox, rotate SwivelBase by typing 45 in the Rotate Y channel and pressing Enter.

SwivelBase rotates in the view but the mechanical arm does not rotate. You first might think
something is wrong because SwivelBase and all of the arm's skeletons and surfaces are parented
into the same hierarchy.

NoteYou may sometimes discover that something doesn't work in the manner you originally anticipated
when setting up an IK system. When this occurs, it's useful to stop and diagnose why something is
working the way it is (or not working the way it should). In that way you can retrace your actions to
determine where the problem resides.

ArmControl and IK Handle are not parented into the SwivelBase hierarchy. Because ArmControl and IK
Handle control the movements of the mechanical arm, they must be parented into the SwivelBase
hierarchy in order for the arm to rotate when SwivelBase is rotated.

To parent the IK Handle into the skeleton hierarchy

1. In the Hypergraph, select the SwivelBase node.
2. In the ChannelBox, reset the Rotate Y channel for SwivelBase to 0.
Setting any previous transformations to zero is necessary before parenting the IK Handle beneath
SwivelBase in the hierarchy.
3. Unselect the SwivelBase node before performing the following steps.
4. In the Hypergraph menu, select View > Frame All.
The Hypergraph displays all the nodes for the scene.
5. In the Hypergraph, shift-select the nodes named ikHandle1, ArmControl, and SwivelBase.
The order of selection is important. You want to shift-select the items that will be the child nodes
first, and then shift-select the item that will be the parent node last.
6. In the main menu, select Edit > Parent (Hotkey p).
In the Hypergraph, IKHandle and ArmControl are now child nodes for the SwivelBase node in the
skeleton hierarchy.

Select Edit > Reset Settings to set the tool

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Constraining an IK system
You can constrain the IK Handle to the control object (ArmControl) using a point constraint. A point
constraint allows the transformation attributes of one object to be controlled by the transformations of
another object. For example, you select and position ArmControl without having to touch the IK Handle.
You also set the constraint so ArmControl maintains the current distance (offset) from the IK Handle. The
offset ensures that the constrained IK handle doesn't move to the same position as the control object.

To constrain the IK Handle to the control object

1. In the Hypergraph, select the ArmControl node and then shift select the ikHandle1 node.
The order of selection when applying a constraint is important: you must select the constraining
object first, and the item to be constrained second.

2. In the main menu, select Constrain > Point > .
The Point Constraint Options window appears.

3. In the Point Constraint Options window, do the following:
o Select Edit > Reset Settings to set the tool to its default settings.
o Turn on the Maintain Offset setting.
o Click the Add button.

The IK handle is constrained to the control object. In the Hypergraph, a constraint node is
created beneath the ikHandle1 node.

4. In the Hypergraph, select only the ArmControl node.

5. In the Toolbox, select the Move Tool.

6. In the side view, drag the manipulator to reposition the control object. (Experiment with a few
different positions in the side view only.)

When you drag the manipulator, the control object moves, which in turn moves the IKHandle.
Because the IK handle controls the skeleton and the mechanical arm model, they also move. The
offset between the control object and the IK Handle is maintained.

The Cargo Magnet does not continuously point downwards when rotated. Its orientation is based on the
original rotation it had in its original position.

The mechanical arm will be easier to pose if you set Cargo Magnet to be oriented downwards towards
the floor of the scene regardless of the orientation of the other components of the arm.

You make CargoMagnet point downwards using an orient constraint. An orient constraint constrains the
orientation (rotation) of the X, Y, and Z axes of one object to match those of the constraining (target)
object.
In the next steps, you reset the position of the mechanical arm to its default position, and then apply an
orient constraint to the last joint in the IK system so that its orientation matches the control object. The
effect is that CargoMagnet points downwards regardless of any other movement in the scene.

To set the IK system to its default position

1. In the Hypergraph, select the ArmControl node.
2. Open the Channel Box by clicking the Show/Hide Channel Box icon.

3. In the Channel Box, set the X, Y, and Z transformations for ArmControl to 0.
Zeroing the transformations on ArmControl resets the mechanical arm to its home position because
of the freeze transformations step you performed in the previous section.
4. Close the Channel Box by clicking the Show/Hide Channel Box icon.

To apply an orient constraint for the IK system

1. In the Hypergraph menu, select View > Frame All.
The Hypergraph displays all the nodes in the scene.

2. In the Hypergraph, select ArmControl and then shift-select the node named joint4. (You may
need to dolly and track the Hypergraph view to view these nodes.)

3. In the Main Menu bar, select Constrain > Orient > .

4. In the Orient Constraint Options window, do the following:
o Select Edit > Reset Settings to set the tool to the default settings.
o Click the Add button.
Joint4 is constrained to have the same orientation as the control object. In the Hypergraph, the
constraint node is created below the joint4 node in the hierarchy.

5. With only the ArmControl node selected, use the Move Tool to reposition ArmControl in the side view.

CargoMagnet maintains an orientation facing the floor of the scene regardless of how the
mechanical arm is positioned in the side view.

In the next section, you learn how to limit the range of movement for the IK system.

To simplify the display of the Arm Control node

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To freeze the transformations for the control object

1. In the Hypergraph, select the node named ArmControl.
The control object is selected in the scene view.
2. In the main menu, select Modify > Freeze Transformations > .
3. In the Freeze Transformation Options window do the following:
o Select Edit > Reset Settings to set the tool to its default settings.
o Click the Freeze Transform button.

The transformations for ArmControl are set to zero. From this point onwards, you can reset its
position to this location by zeroing its translations in the Channel Box.

To easily identify the locator as the control object in the scene view, label the control object using an
annotation. An annotation is a text label that can be set to point at the labeled item. Annotations are
useful because they always face the viewer, regardless of the orientation of the model in the scene view.

To label the control object in the scene view

1. In the Hypergraph, select the ArmControl node.
2. In the main menu, select Create > Annotation.
A input window appears.
3. Type ArmControl and click OK.
In the scene view, the word ArmControl appears near the locator/control object. In the
Hypergraph, two new nodes appear in a hierarchy beneath ArmControl.

4. With the annotation still selected, select the Move Tool.
5. In the side view, drag only the annotation so it appears slightly offset from the locator object as
shown below.

The annotation displays in any scene view so you can easily identify the control object for
selection.

To simplify the display of the Arm Control node

1. In the Hypergraph, right-click the ArmControl node. Choose Collapse from the pop-up menu. (You
can also double-click a node to collapse or expand the hierarchy below it.)

The ArmControl node appears as a single node instead of the previous three node hierarchy. The
small arrowhead on the lower left-hand corner of the node indicates that the node is collapsed.

The control object must be linked to the IK Handle to control the IK Handle.

IK Handle to pose an IK chain is generally not a good practice

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Creating a control object for an IK system

Using the IK Handle to pose an IK chain is generally not a good practice. The IK Handle can be
challenging to select in the scene view, especially when it's grouped into a hierarchy that includes a
skeleton and other surface components. A better practice is to create a control object.

You create a control object to select and manipulate an IK system instead of directly using the IK
Handle. You can create a control object with a curve or a locator, which are often used because they
don't appear in the rendered image.

The control object controls the movement of the IK Handle using a constraint. You can constrain the
position, orientation, or scale of an object to other objects using constraints.

To create a control object:

Create and position the control object in the scene view.
Name the node for the control object in the Hypergraph.
Freeze transformations for the control object.
Label the control object in the scene view.
Constrain the IK Handle to the control object.

To create a control object using a locator

1. From the main menu, select Create > Locator.
A three-dimensional cross is created at the origin in the scene view.

2. Select the Move Tool from the Toolbox.

3. In the side view, reposition the locator slightly above and in front of the end of the mechanical
arm as shown in the image below.

To easily identify the locator as a control object in the Hypergraph, rename the locator.

To rename the control object using the Hypergraph

1. In the Hypergraph, right-click the node named locator1. Choose Rename from the pop-up menu
that appears.
The locator1 name is highlighted on the node.

2. Type the name ArmControl and press Enter to save the name for the locator.

Before you constrain the IK handle to the control object, you need to freeze the transformations for the
control object. Freeze Transformations zeros the transformations for an object without changing the
position of the object. This is another good practice; If it becomes necessary to reset the arm to its
default position, you can set the transformation on the control object to zero, and the arm will return to
this default pose.

used by the IK solver to calculate the rotation of the joints in the IK chain

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Applying IK to a skeleton hierarchy

IK allows you to control the joint rotations in a skeleton using an IK handle. You pose the skeleton by
positioning the IK handle (usually located at the end extremity of the skeleton) and having the rotations
for the other joints calculated automatically by the IK solver. In the steps that follow, you apply IK to
the skeletal hierarchy.

To create an IK handle for the mechanical arm

1. From the main menu, select Skeleton > IK Handle Tool > .
The IK Handle Tool Settings window for the Joint Tool appears. When the mouse pointer is in the
orthographic view its appearance changes to the tool's cross hair cursor.

2. In the IK Handle Tool settings window, do the following:

o Click Reset Tool to set the tool to its default settings.
o Set the IK Handle Settings: Current Solver - ikSCsolver.

o Hide the Tool Settings window by clicking the right-pointing arrow that is located in the upper
left corner of the Tool Settings window.

The ikSCsolver setting selects the IK Single Chain Solver. This solver ensures that the joints in the
skeleton will lie along a single plane. This solver is well suited for the mechanical arm, because the
arm doesn't need to twist unlike a real arm.

 Working in the side view, starting from the base of the mechanical arm, do the following:
o Click on the skeleton joint at the base of the mechanical arm.

o Click on the skeleton joint at the tip of the mechanical arm. (The IK Tool is designed to attach
to the joints closest to your selection point.)

In the side view, the IK handle is drawn as a line from the start and end joints of the IK chain.

4. In the Hypergraph menu, select View > Frame All.

In the Hypergraph, two new nodes appear in the hierarchy that represent the IK chain: an IK
Handle node and an end effector node.

5. In the Hypergraph, select the node named ikHandle1.

The IK Handle (in combination with the end effector) is used by the IK solver to calculate the
rotation of the joints in the IK chain. By default, the IK Handle is located at the last joint of the IK
chain in the scene view.

6. Select the Move Tool from the Toolbox, and drag the Move Tool's X axis manipulator (blue arrow)
to reposition the mechanical arm.

When you drag the manipulator, the skeleton and mechanical arm model are repositioned.

7. Reset the mechanical arm to its previous position by selecting Edit > Undo until the mechanical
arm is positioned into its previous orientation.

Note

When using the Undo feature, do not undo so many times you inadvertently undo the IK handle you've
just created.

The next steps describe how to manipulate the IK Handle using a control object.

the Hypergraph view as required to view the new hierarchy

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Parenting a model into a skeleton hierarchy

Parenting is the term used when placing a node beneath another in a hierarchy so it becomes the child
of the node above it (its parent) in the hierarchy.

In the following steps, you add the surfaces of the mechanical arm model into the skeleton hierarchy.
This process links the models' surfaces to the skeleton hierarchy making it possible to pose and animate
the model like a real mechanical arm. Using the Hypergraph to select the nodes allows you to better
visualize the process and the hierarchical relationships that result.

Note

The following parenting procedure works well for the mechanical arm (no organic bending or
deformation occurs) and provides one technique for adding modeled objects to a skeletal hierarchy.
A more common technique for combining a character model into a skeleton hierarchy is referred to as
skinning or binding. The Bind Skin tool combines the surface components and joints together into a
hierarchy and also takes into account any deformations that may occur when a character bends or
flexes (knees, waist, neck, elbows etc.). Maya provides a few methods for skinning. For more
information see Skeletons and skinning in the Maya Help. For a tutorial on skinning see Smooth skinning.

To parent the mechanical arm into the skeleton

1. In the Hypergraph menu, select View > Frame All.

The Hypergraph displays all the nodes for the scene.

2. In the Hypergraph, select the node named ArmEnd and then shift-select the node named joint4.
The order of selection is important. You want to select the child node first, and then shift-select
the item that will become the parent node second.

3. In the main menu, select Edit > Parent (Hotkey p).
In the Hypergraph, joint4 is now the parent node for the Arm_end node in the skeleton hierarchy.

4. Repeat the parenting process for the following items:

o pin3 is parented under joint3
o pin2 is parented under joint2
o pin1 is parented under joint1

Your new hierarchy should appear as shown in the diagram below.
.

In the next steps, SwivelBase becomes the parent node for the new hierarchy so that the entire
arm assembly swivels about the center of the base component.

5. In the Hypergraph, select the node named joint1 and then shift-select the node named
SwivelBase.

6. In the main menu, select Edit > Parent (Hotkey p).
Change the panel display to a layout that allows you to view the hierarchy in the Hypergraph.

7. In the side view menu, select Panels > Layouts > Two panes side by side.
The panels display in a side by side configuration.

8. Dolly the Hypergraph view as required to view the new hierarchy.

9. In the Hypergraph, select the node named Swivel_base.
In the side view, observe that both the mechanical arm model and the skeleton are selected.
Swivel_base is the parent or root node for the hierarchy. If you rotate SwivelBase, everything else
below that node (the entire arm with skeleton) rotates.

10. Select the node named joint3.
Observe that the last two components of the mechanical arm are selected. If you rotate joint3,
only the components below that node in the hierarchy will be affected.

11. Select the node named pin2.
Observe that only one isolated segment of the model is selected. No other components or joints
are selected when pin2 node is selected. If you rotate the model at pin2, only the component at
pin2 will rotate in isolation from the rest of the hierarchy because it is located lower in the
hierarchy.

It is now possible to select and rotate the skeleton joints to pose the mechanical arm as a unit, and
then set keyframes to animate it. Posing a character using joint rotations is referred to as Forward
Kinematics (FK). FK allows for precise control when setting up a pose, but it can be a time consuming
process to select and rotate each joint into the desired position.

When an animation is more focused on the goal of placing the end joint in a hierarchy in a particular
position, (for example, a hand or a foot), it is more efficient to use Inverse Kinematics to pose the
skeleton. For more information on forward and inverse kinematics, see Posing skeletons in the Maya Help.

Note
It's not a simple matter to state that one technique or another is the only approach to achieving a
desired result when animating in Maya. You must decide whether a particular technique works for a
particular scenario based on the options it provides. A combination of animation techniques can be
creatively used in a variety of ways.

an item using the Hypergraph

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Viewing hierarchies using the Hypergraph

In the following steps, you use the Hypergraph to view the hierarchy for the mechanical arm. The

Hypergraph is a scene management editor that presents a graphical view of the scene hierarchy. It allows

you to more easily create, understand, and manage the hierarchy of objects and nodes in your scene.

To view hierarchies using the Hypergraph

1. From the perspective view's panel menu, select Panel > Layouts > Two Panes Stacked.

The workspace displays two panels stacked on top of each other with an identical perspective

view of the scene.

2. In the lower panel, select Panel > Panel > Hypergraph.

The lower panel displays the Hypergraph.

3. In the Hypergraph menu, select Graph > Scene Hierarchy.

If the menu item appears dimmed, it indicates that the Hypergraph is already displaying the scene

hierarchy

The Hypergraph displays with a black background by default. In order to see the relationships

between the items, the background has been modified for the images in this lesson.

4. In the Hypergraph menu, select View > Frame All to see all the components of your scene.

The boxes represent the nodes for the various items in the scene. Some items in the scene have already

been parented into a hierarchy. This is indicated by the lines connecting some of the nodes. Selecting

the nodes in the Hypergraph also selects the item in the scene view.

To select an item using the Hypergraph

 In the Hypergraph, click each of the separate items in the hierarchy at the parent level to select

them. At the same time, observe which objects become highlighted on the model in the

perspective view.

Hierarchies combine the various objects into discrete components for the mechanical arm, that is, the

base, lower arm, middle arm, upper arm, etc. If you select and rotate any of the parent nodes in the

hierarchies, none of the other arm components follow because they are not combined into one unified

hierarchy.

Creating a skeleton hierarchy

To link the various components of the mechanical arm into a hierarchy that can be posed, you need to
create a skeleton. A skeleton is a hierarchy of joints that are connected together with bones.
In the scene, a joint represents a special type of node that gets created in a skeleton hierarchy. A joint
acts as the parent node for any other joints that occur in the hierarchy below it. Each joint has a
rotational pivot point associated with it. A bone is the visual representation used in the scene view to
connect the joints and help visualize the joint chain.

A skeleton is similar to a skeleton in the real world in that it acts as the underlying structure for the
surfaces to be attached. While you can view the skeleton with its bones and joints in the scene view, it
does not appear in your rendered images. Its purpose is to assist you in setting up and posing your
models and characters and to visualize the motion you want to achieve.

Skeletons are integral to the animation of any character or hierarchical model. Examples of characters
that use skeletons are two and four legged animals. Skeletons are also useful for animating other organic
components such as the tail of an animal, a tentacle of an octopus, or a snake.

In the following steps, you create a simple skeleton consisting of four joints that you combine with the
mechanical arm model into a skeleton hierarchy, allowing you to pose and animate the model.

To create a skeleton for the mechanical arm

1. In the perspective view menu, select Panels > Orthographic > side.
The view updates to display the side view.

You need to view the components of the mechanical arm fully in the side view so you can draw
the joints for the skeleton.

2. Resize the side view to a larger size by dragging the border between the side and Hypergraph
panel views downwards.

3. In the side view menu, select Shading > Wireframe (Hotkey 4).

4. From the main menu, select Skeleton > Joint Tool > .
The Tool Settings window for the Joint Tool appears. The Joint Tool is used to create the joints
and bones for a skeleton.

5. In the Joint Tool settings window, do the following:

o Click Reset Tool to set the tool to its default settings.

o Hide the Tool Settings window by clicking the right-pointing arrow that is located in the upper
left corner of the Tool Settings window.

 In the side view, starting from the base of the mechanical arm, do the following:

o Click in the center of each pivot pin on the mechanical arm to place four joints as shown in the
image below.

Try to click as close to the center of each pivot pin as you can, as the rotation of the joints on
the model will be based on the location of the joints on the skeleton. As you place the joints, a
bone appears, connecting each joint. (Because the model lies along the YZ plane, the joints are
created close to the center of each corresponding joint on the mechanical arm model.)

o After you place the fourth joint, press Enter to indicate that the last joint has been placed.

7. In the Hypergraph, dolly the view to see the skeleton node hierarchy you just created. (It appears
at the right side of the view.)

8. In the Hypergraph, select the joint1 node.

The entire skeleton becomes selected. Any rotations on this node also affect anything lower down
the hierarchy.

9. Select joint2 (You can also press the down arrow on your keyboard to select further down the
hierarchy).

The skeleton is selected from joint2 downwards in the hierarchy. Any rotations that you make on
this node affect only joint2 and nodes below joint2.

Once a skeletal hierarchy is created, the various surface components can be added to the hierarchy.