🦴Retargeting

With Kinetix's proprietary retargeting algorithm, emotes created using the User-Generated Emote feature can be played on any humanoid avatar.

What is retargeting?

Emote retargeting is a powerful technique in the world of 3D animation. It allows you to transfer an animation from one avatar to another, regardless of their size, proportions, or skeletal structure. Instead of creating a unique animation for each character, emote retargeting streamlines the process by adapting a single emote to fit various avatars.

Kinetix's Proprietary Retargeting Algorithm

Each character in a 3D animation typically has a skeletal structure with bones and joints. All the Emotes from the Kinetix Emote Library and User-Generated Emotes are created for a specific and standard character with a standard skeleton.

Kinetix's proprietary algorithm is able to transfer the motion from Kinetix's standard avatar to the target's avatar, almost fully automatically. The algorithm will proactively identify the correspondence between the bones of the target skeleton and those of the source skeleton, and the user will then need to confirm and correct errors if necessary. Once the Bone Mapping is done, Kinetix's Retargeting Algorithm will adapt the motion to the target avatar's bones proportions to ensure that the movement is smooth and great.

Here is what the Kinetix Standard Skeleton looks like:

Mandatory bones:

Kinetix's skeleton main bones.

Additional Bones

Kinetix's skeleton "additional bones".

Hand bones

Kinetix's hand bones. Bone 0 is the closest to the palm, while bone 2 is always at the extremity of the finger.

Bone Mapping

Bone Mapping is a crucial, semi-automated part of the retargeting process. It allows our AI to understand the target's skeletal structure and adapt the motion from the Kinetix Standard Avatar to the target avatar.

When a user imports an avatar, Kinetix's Bone Mapping algorithm will analyze the skeleton of the character and identify his bones and joints. Our AI will try to figure out which bone from the uploaded skeleton matches the original bone from the source skeleton, and repeat this identification process for the whole skeleton.

In a matter of seconds, our algorithm presents the results of this mapping, allowing the user to review and fine-tune the automatic bone mapping. This empowers users to correct any incorrectly assigned bones and map any unassigned bones, resulting in precise skeletal adaptation for animation, thereby saving time and ensuring animation accuracy.

Kinetix's Bone Mapping on the Developer Portal

Contact-Aware Retargeting

When target avatars feature intricate designs, such as unusual bone structures, very particular bone lengths, complex morphologies, or incorporate wearables, it can potentially lead to issues like inter-penetrations that diminish the overall output quality.

To address this concern, Kinetix has devised a unique retargeting method that factors in the character's mesh, proactively anticipating and mitigating contact errors. In this process, the algorithm strategically positions 45 key points among the character's vertices, effectively capturing the character's comprehensive morphology.

Example of vertex key points

Key points help us compute the different morphologies

After correctly positioning the key points, our algorithm takes charge of the retargeting process. As usual, it seamlessly transfers the motion from the source's joints and bones to the target's skeletal structure, but this time, the motion is optimized while adhering to the constraints set by the key points.

Here is an output sample that highlights the value of the Contact-Aware retargeting:

Our algorithm makes sure the character's belly and arms do not go under the ground.