Parenting and Grouping
Maya 2012 Tutorial
How to Groups and Parent Objects in Maya
Parenting and grouping are used to establish a hierarchy between objects. For instance, you may want to rotate several objects around a single point. By grouping the objects, you would only need to rotate the group object and the others would follow.
The main difference between parenting and grouping is that grouped objects are connected to a single null object and parented objects connect to a single parent object. To select a group you would select the null group object. A parent and all it's children are selected by clicking the parent object in the workspace.
Add a NURBs sphere to the workspace by choosing Create > NURBs Primitives > Sphere.
Select the sphere, open the Channel Box and change the TranslateX value to 10.
In the top view, select the object, then select the Move tool (w key).
Press and hold the d key to access the object's pivot point. Drag the pivot point to the workspace origin.
Choose Edit > Duplicate Special (include options).
Enter 72 for the y rotation and 4 in the Number of Copies box, then click Duplicate Special.
Select all five of the spheres and choose Edit > Group (Command/g (PC - Ctrl/g)).
Choose Window > Outliner. Notice that the spheres are now located inside the group. Click the group name in the Outliner to select the entire group.
Select the Rotate tool (e key) and rotate the group in the workspace. As you rotate the group, all it's members rotate as well.
You can also select a group of objects by deselecting the group and then activate the Select by Hierarchy and Combinations feature. Once you click the icon, click any of the group members and the entire group is selected.
To demonstrate parenting, let's open a new scene and add three cubes by choosing Create > Polygon Primitives > Cube.
Using the Move tool (w key), distribute the objects in the scene.
Select the third cube, then shift-select the second cube. Choose Edit > Parent (p key). The middle cube is now the parent of the third cube.
Choose Window > Outliner and notice hierarchy between the second and third cubes.
To make the second cube a child of the first cube, middle-mouse drag pCube2 to pCube1.
Select the Move tool (w key) and move the cubes in the workspace. Moving pCube1 affects all three cubes, pCube2 moves itself and pCube3 and pCube3 has no children.
Order is Important
Whenever you establish a parent/child relationship the order that the objects are selected is very important. The last object you select will be the parent.
Setting the Children Free
To remove a child from a parent/child relationship, select the child and choose Edit > Unparent (Shift/p).
To ungroup a set of objects, select the group in the Outliner and choose Edit > Ungroup.