Preferred Postures

Useability of Preferred Postures

Preferred Postures are special type of constraints for our inverse kinematics system. Preferred Posture allows repeatability of the IK solver. The IK solution can vary given the same position and orientation of the IK Effectors as seen in the following figure.

A Preferred Posture minimizes this variation in the solution by pulling the solution as close to a given Preferred Posture as possible. The following figure shows the results of using IK with and without a Preferred Posture applied.

The Preferred Posture can be seen as a faint Red Skeleton in the viewport. As can be seen with a Preferred Posture applied the knees never bend backwards. This is because the IK is trying to pull the solution to the given Preferred Posture. If the Preferred Posture was set with the knees bent backwards then the keens would not bend forwards. In this way a Preferred Posture can be very helpful tool when the user wants the IK to be reliable and behave as per his / her requirements.

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Creating a Preferred Posture

Preferred Postures can be created using the ToolBox. The user can create a Preferred Posture at the current time frame in the Timeline, a Preferred Posture Icon will appear in the Timeline where the Preferred Posture was created. Preferred Posture Icons can be dragged to another time frame if needed. The user can create as many Preferred Postures as he needs in the Timeline. Each Preferred Posture will store the state of all the Skeletons in the scene. Properties of a Preferred Posture can be changed by selecting the Preferred Posture Icon and modifying it in the Settings panel.

Important Note: Preferred Posture will only become visible in the viewport if there exits a Preferred Posture Icon at the current time frame. Only the current Preferred Posture will be used by the IK. If the user wants to use a Preferred Posture which is not the current one then simply select the specific Preferred Posture Icon in the Timeline. The selected Preferred Posture will then override the current Preferred Posture in the viewport and will be used by the IK.

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Types of Preferred Postures

Preferred Postures can be one of two types : static or updating. A static Preferred Posture does not update until the user specifically updates it. An updating Preferred Posture automatically updates to the new posture whenever the user interacts with the skeleton. This is especially useful if the user wants to keep the IK solution as close to the current state of the skeleton. The type of Preferred Posture can be set from the ToolBox or the Preferred Posture Settings panel.