Prevent rolling effects for aim constraints

User Guide > Rigging > Character Setup > Constraints > Edit constraints > Edit aim constraints >

In certain situations, a constrained object can rapidly roll about its aim vector. Rolling effects can happen when the aim vector approaches or points in the same direction or in the opposite direction as the up vector. For more information, see Rolling effects.

You can avoid rolling effects by keeping the target point clear of the world up vector’s direction. For example, if the world up vector points in the direction of the scene’s world space Y-axis (the default), you would try to avoid having the positive or negative Y-axis intersect the target point. You could move the target object(s) as needed, or perhaps change the target object weights so that the target point does not get to close to the Y-axis.

However, if your animation makes such avoidances impossible, you can prevent rolling by changing or animating the world up vector.

To change world up vector for aim constraints with the Attribute Editor

Edit the World Up Vector attribute as described in Edit aim constraint attributes. Note that you can also use the Channel Box to edit the World Up Vector.

To animate world up vector for aim constraints with the Channel Box

You can set keys on the World Up Vector attribute by using the Channel Box. To select the World Up Vector attribute, see Edit aim constraint channels. To set keys on the World Up Vector, select the World Up Vector attribute, -click it, and select Key Selected form the pop-up menu that appears.