Animation Retargeting Squash Stretch Angular Configuration

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Solution Overview

Problem

Existing animation retargeting systems for virtual actors suffer from artifacts when mapping animation from one model to another with different sizes or topologies, leading to unnatural animations with 'popping' articulations and loss of angular configuration.

Innovation Solution

A system that incorporates a squash and stretch module to retarget animation by scaling bones of the destination virtual actor to match the angular configuration of the source, using inverse kinematics goals and adjustable parameters like Stretch Start, Squash Start, Maximum Stretch, and Maximum Squash to control scaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If animation is retargeted from source to destination characters with different sizes or topologies, then animation reuse is enabled, but artifacts and loss of angular configuration occur

Engineering Contradiction:

Improveanimation reuse capabilityVSAvoidangular configuration preservation

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system dynamically changes the scale parameter of destination character bones based on the source character's angular configuration. By computing scale factors from the ratio of bone lengths and adjusting bone scales iteratively, the system adapts the animation to preserve angular relationships while accommodating size differences between characters.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The retargeting system employs dynamic iteration to compute and apply scale factors. Instead of using a fixed scale, the system iteratively adjusts bone scales based on current angular configurations, allowing the transformation to adapt dynamically throughout the animation sequence to maintain natural motion.

Inventive Principle:

Principle #15Dynamics

2Loss of time

If conventional retargeting is used to map animation between different models, then development time is reduced, but artifacts with popping articulations appear

Engineering Contradiction:

Improveanimation development timeVSAvoidanimation quality

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The system implements feedback by computing scale factors based on the actual angular configuration of source character bones and applying these scales to destination bones. This feedback loop continuously adjusts the retargeting transformation to minimize artifacts and maintain natural articulation throughout the animation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary computation of scale factors based on bone length ratios before applying the retargeting transformation. By pre-calculating appropriate scale adjustments, the system prepares the transformation parameters in advance, enabling smooth retargeting without runtime artifacts.

Inventive Principle:

Principle #10Preliminary action

3Length of stationary object

If bone scaling is applied to match character sizes, then size difference is compensated, but angular configuration may be distorted

Engineering Contradiction:

Improvecharacter size matchingVSAvoidangular configuration

Core Design Contradiction:

Length of stationary objectVSShape

Solution Approach 1:

The system changes the scale parameter of destination bones dynamically based on the source character's angular configuration. By computing scale factors from bone length ratios and applying them iteratively, the system achieves size matching while preserving the angular relationships that define the character's pose and motion.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10083536B2System for mapping animation from a source character to a destination character while conserving angular configuration

Publication Date: 2018.09.25 AUTODESK INC

AI summary

A system is discussed herein that that stretches or squashes the target body parts based on a relative size difference between a source and the target. The angular configuration of the source is matched exactly in the destination. The system allows a squash or stretch of a part to be determined from a goal determined by the source actor.