Houdini 20.0 Nodes Geometry nodes

MotionClip Extract Key Poses geometry node

Identifies the key poses of an animation

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Since 18.5

This SOP takes as input a MotionClip and outputs a MotionClip with only the most important poses for defining the motion of the character.

This SOP lets the user specify a number of key poses to output, the maximum number of poses in between key poses, and what method to use to measure the quality of a sequence of key poses. It then uses these parameters to determine an optimal set of key poses for the animation which starts with the first pose and ends with the last pose.

State

This viewport state allows you to visualize a MotionClip or its evaluated poses over time using a color ramp, and it is available for every MotionClip SOP node that outputs a MotionClip.

MotionClip viewport state interaction

You can select individual joints from the current pose in the MotionClip viewport state. For the selected joints, you can then use the Evaluate Pose mode to view just the current pose, its selected joints, and the motion trails for those joints.

rFoot and lFoot joints selected, Mode = Evaluate Pose, Color = White to Red
MotionClip viewport state toolbar

Mode

Determines the MotionClip information that is displayed in the viewport.

MotionClip

Displays all the MotionClip’s poses.

Mode = MotionClip

Evaluate Pose

Displays a single MotionClip pose at the current time.

Mode = Evaluate Pose

Transparent MotionClip

When turned on, the MotionClip’s poses are displayed as fainter lines, making it easier to see the scene behind the MotionClip, as well as the evaluated pose.

Color

Applies the selected color ramp preset to the MotionClip’s visualization in the viewport. This color ramp helps to visualize changes to the MotionClip or individual poses over time.

Mode = Evaluate Pose, Color = White to Red

Extend Color

Determines how the poses outside of the MotionClip’s defined animation start and end range are visualized in the viewport.

Hold

Holds the color values at the ends of the range.

Mode = MotionClip, Color = Plasma, Extended Color = Hold

Gray

Poses outside the animation start and end range are colored gray.

Mode = MotionClip, Color = Plasma, Extended Color = Gray

Hide

Hides the poses outside the animation start and end range.

Mode = MotionClip, Color = Plasma, Extended Color = Hide

Parameters

Key Poses

Output Method

The method used to determine the output of the node.

Extract Key Poses

The output will be a MotionClip containing only the key poses of the input MotionClip.

Identify Key Poses

The output will be a copy of the input MotionClip with an additional 'keypose' primitive attribute. For each pose, this primitive attribute will have a value of 1 on each key pose and 0 on every other pose.

Repack Attributes

When enabled, the attributes defined by the Rest Attributes and Animated Attributes patterns will be evaluated from the input MotionClip and packed into the output MotionClip in the extracted key poses. This will result in all of these attributes becoming animated attributes on the output MotionClip.

For more details on what distinguishes an animated attribute from a rest attribute, see the Attributes folder on the MotionClip Evaluate SOP.

This parameter is only available when Output Method is set to Extract Key Poses.

Tip

To maintain the attributes which were previously animated without adding any additional attributes to the poses, toggle Repack Attributes on, clear Rest Attributes, and set Animated Attributes to *.

These are the default values for these parameters.

Rest Attributes

The attributes that should be unpacked from the rest pose of the input MotionClip. All attributes that match this pattern will become animated attributes on the output MotionClip.

This parameter is only available when Output Method is set to Extract Key Poses.

Animated Attributes

The attributes that should be evaluated from the animated poses of the input MotionClip. All attributes that match this pattern will remain animated on the output MotionClip.

This parameter is only available when Output Method is set to Extract Key Poses.

Optimization Method

The method used to determine the optimal set of key poses.

Minimize Worst Pose

The error in the worst pose of the interpolated animation will be minimized.

Minimize Worst Joint

The error in the worst joint of the interpolated animation will be minimized.

Minimize Average Pose

The error in the average pose of the animation will be minimized.

Target

How the node computes the number of key poses to extract: reduce to a percentage of the initial number of poses and reduce to a fixed number of poses.

Percent to Keep

When Target is “Percentage of Input Poses”, this specifies what percentage of the original poses to extract as key poses.

Key Poses

When Target is “Pose Count”, this specifies the number of key poses to extract.

Continue reducing within quality tolerance

When this is on, MotionClip Extract Key Poses will opportunistically reduce the number of key poses beyond the target as long as it can do so while matching the original shape within a certain quality tolerance. Turn this on if the target is your goal but you would be happy to get fewer key poses in the result.

Tolerance

When Continue reducing within quality tolerance is on, after MotionClip Extract Key Poses reaches the target, it will continue to remove poses as long as the difference in quality measurement is within this tolerance. The quality measurement is determined by Optimization Method.

Max Step

The maximum number of poses of the input animation between key poses of the output animation. Reducing this increases the efficiency of the node. If this is disabled, the maximum number of poses between key poses will not be limited.

Frame Range

Trim Poses Outside of the Clip Range

If enabled, the poses which are defined outside of the range defined by the clipinfo detail attribute will be trimmed with the exception of the first pose at or before the beginning of the range and the first pose at or after the end of the range.

Frame Range

The range of the input frames over which to extract key poses. Frames outside of this range will remain unaltered.

Inputs

MotionClip

The MotionClip from which the key poses are extracted.

Outputs

MotionClip

A MotionClip containing only the key poses of the input MotionClip.

See also

Geometry nodes