InsActor: Instruction-driven Physics-based Characters
(2312.17135)Abstract
Generating animation of physics-based characters with intuitive control has long been a desirable task with numerous applications. However, generating physically simulated animations that reflect high-level human instructions remains a difficult problem due to the complexity of physical environments and the richness of human language. In this paper, we present InsActor, a principled generative framework that leverages recent advancements in diffusion-based human motion models to produce instruction-driven animations of physics-based characters. Our framework empowers InsActor to capture complex relationships between high-level human instructions and character motions by employing diffusion policies for flexibly conditioned motion planning. To overcome invalid states and infeasible state transitions in planned motions, InsActor discovers low-level skills and maps plans to latent skill sequences in a compact latent space. Extensive experiments demonstrate that InsActor achieves state-of-the-art results on various tasks, including instruction-driven motion generation and instruction-driven waypoint heading. Notably, the ability of InsActor to generate physically simulated animations using high-level human instructions makes it a valuable tool, particularly in executing long-horizon tasks with a rich set of instructions.
Overview
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InsActor introduces a new approach to creating physics-based character animations from high-level human instructions using a hierarchical framework.
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The framework combines language-conditioned diffusion models for motion planning with skill discovery mechanisms for smooth state transitions.
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Experimentation shows that InsActor achieves state-of-the-art results in interpreting instructions and in its robustness to environmental perturbations.
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The applications for InsActor span video game design, virtual reality, and robotics, showcasing its adaptability and potential for creating visual instruction representations.
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Future developments could focus on scalability, diversity in human morphology representation, and ethical considerations of technology use.
Introduction to Instruction-driven Animation
In recent years, there has been significant interest in creating animations that are not only visually realistic but can also be controlled intuitively through human instructions. This area of animation seeks to bridge the gap between high-level human commands and the generation of fluid physics-based character movements. Conventional approaches, like motion tracking, often face challenges in mapping these commands and struggle with complex instructions. On the other hand, conditional generative models might lack the finesse for precise control. A new approach called InsActor proposes to mitigate these issues with a hierarchical framework that uses diffusion models and skill discovery techniques.
The InsActor Framework
The InsActor framework combines high-level motion planning with low-level skill execution to produce animations that can be directed by human language instructions. Using the language-conditioned diffusion model, it initially generates a series of states (actions) based on the given commands. However, while this model captures the essence of the command-to-motion relationship, it might not guarantee feasible transitions between states, which is critical for smooth animations.
To combat this, InsActor employs a skill discovery mechanism. By encoding state transitions into a compact latent space, it maps these transition pairs to skill embeddings, translating them into appropriate animations. With this approach, InsActor breaks down the complex problem into manageable tasks across two different levels, offering adaptability and scalability.
Performance and Applications of InsActor
The real test for the InsActor framework is not only how well it can turn instructions into animations but also its robustness in different conditions and the visual plausibility of its output. Through extensive experimentation, it has been shown to achieve state-of-the-art results on a variety of tasks, which include interpreting human instructions and guiding characters through waypoints to specified targets. Importantly, the model can also withstand environmental perturbations, confirming its robustness and real-world applicability.
InsActor's ability to adapt to additional conditions, such as dealing with multiple waypoints and generating animations that comply with both historical and future objectives, demonstrates its broad potential for applications in video game design, virtual reality, and even in fields like robotics where visual representations of instructions are beneficial.
Looking to the Future
Despite InsActor demonstrating a strong capability in generating intuitive physics-based animations, there's always room for advancement. Improving the computational efficiency of the diffusion model itself is one aspect that could see the system scaling up to more complex environments or data sets. Moreover, broadening the scope to accommodate different human body shapes and morphologies presents another avenue for development.
Finally, as technologies like InsActor grow, they also bring forward ethical considerations about their potential misuse. Therefore, users and creators alike must remain vigilant about responsible applications of these advanced systems.
InsActor stands as a groundbreaking tool in the evolution of physics-based character animation. It achieves a delicate balance between user-input instructions and the generation of visually plausible animations, effectively pushing the boundaries of what can be achieved in this dynamic and evolving field.
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