MotionScript: Natural Language Descriptions for Expressive 3D Human Motions

Payam Jome Yazdian1Eric Liu1Rachel Lagasse1Hamid Mohammadi2Li Cheng2Angelica Lim1

1School of Computing Science, Simon Fraser University, Burnaby, BC, Canada
2Dept. of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada

Original Caption

A person goes from a standing position to a bended knee while gesturing.


MotionScript Enhanced Caption

His left elbow and his left knee are at right angle. From this stance, the left knee extends, and not long after, it bends. Just moments before, both hands are further down than his hips, near to the left ankle. With that pose, his right hand spreads significantly apart from the left ankle and right after, gets closer to the right foot. In the second right before, he moves upwards and in the meantime, moves towards the front. A second later, he shifts far to the left. Simultaneously, both hands spread away from the left foot. Meanwhile, his left hand spreads significantly apart from his left ankle. Shortly after, he shifts downwards and a moment later, he shifts downwards briskly. The right knee is unbent and from that pose, the right knee bends significantly.

teaser image showing an avatar dancing

Paper Code Video Gallery

Abstract


This paper proposes MotionScript, a motion-to-text conversion algorithm and natural language representation for human body motions. MotionScript aims to describe movements in greater detail and with more accuracy than previous natural language approaches. Many motion datasets describe relatively objective and simple actions with little variation on the way they are expressed (e.g. sitting, walking, dribbling a ball). But for expressive actions that contain a diversity of movements in the class (e.g. being sad, dancing), or for actions outside the domain of standard motion capture datasets (e.g. stylistic walking, sign-language, interactions with animals), more specific and granular natural language descriptions are needed. Our proposed MotionScript descriptions differ from existing natural language representations in that it provides direct descriptions in natural language instead of simple action labels or high-level human captions. To the best of our knowledge, this is the first attempt at translating 3D motions to natural language descriptions without requiring training data. Our experiments show that when MotionScript representations are used in a text-to-motion neural task, large language models can be used to generate unseen complex motions.

Video


Approach


image showing framework of how MotionScript works

The process of generating textual representation of human motions is synthesized directly from 3D skeleton sequences. First posecodes, a quantifiable representation of static pose attributes, are extracted. Next, temporal changes are evaluated in posecodes over time to capture the dynamic aspect of motions in a categorical form. Finally, a methodology that identifies motioncodes, a novel representation of movement patterns, is applied. Afterwards, a selection process is applied on the detected motioncodes to filter out redundant information and aggregate them to convert the motioncodes into concise and coherent natural language sentences.

Results



Dancing



Original Caption

The body is in a dancing action while doing a performance.


MotionScript Enhanced Caption

The left elbow advances from behind the right one to in front of the right one. At the same time, she moves a great distance to the right. Meanwhile, she moves a bit downwards. At the same time, the right hand moves from behind the left one to a position in front of the left one and comes significantly closer to the left knee. She moves slightly downwards speedily. Simultaneously, she shifts forward.

teaser image showing an avatar dancing

Original Caption

The person is performing while in a dancing action.


MotionScript Enhanced Caption

She shifts a great distance backward rapidly. The left hand lifts from below the neck ascending to above the neck. She shifts slightly downwards and a second later, she shifts to the right just a little bit. In the second right before, both knees are bent slightly and from this position, her right knee bends and speedily. Meanwhile, her left elbow is almost completely bent and from this stance, her left elbow extends.

teaser image showing an avatar dancing

Original Caption

This person is going backwards and is dancing.


MotionScript Enhanced Caption

The right hand moves nearer to the right foot. Immediately after, he moves a great distance backward quickly. Right after, the left hand raises from below his neck to above his neck.

teaser image showing an avatar dancing

Original Caption

The subject is performing while making a dance pose.


MotionScript Enhanced Caption

He moves forward and not long after, moves backward.

teaser image showing an avatar dancing

Original Caption

Someone is in a dancing action while doing a performance.


MotionScript Enhanced Caption

He shifts backward just a little bit.

teaser image showing an avatar dancing

Exercise



Original Caption

A person is doing hand exercises while making a dance pose.


MotionScript Enhanced Caption

The right hand moves from the left side of the right shoulder to the right side of the right shoulder, and not long after, it moves from the right side of the right shoulder to the left side of the right shoulder. In the second right before, the right elbow is ahead of his left elbow and is partly bent, and from this stance, his right elbow extends.

teaser image showing an avatar dancing

Original Caption

The subject is lowering a body part and is making hand exercises.


MotionScript Enhanced Caption

The elbows are a bit bent, and from that pose, both elbows bend.

teaser image showing an avatar dancing

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