The N-Body Problem: Parallel Execution from Single-Person Egocentric Video

Fuente: arXiv
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Main Authors: Zhu, Zhifan, Huang, Yifei, Sato, Yoichi, Damen, Dima
Format: Preprint
Published: 2025
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author Zhu, Zhifan
Huang, Yifei
Sato, Yoichi
Damen, Dima
author_facet Zhu, Zhifan
Huang, Yifei
Sato, Yoichi
Damen, Dima
contents Humans can intuitively parallelise complex activities, but can a model learn this from observing a single person? Given one egocentric video, we introduce the N-Body Problem: how N individuals, can hypothetically perform the same set of tasks observed in this video. The goal is to maximise speed-up, but naive assignment of video segments to individuals often violates real-world constraints, leading to physically impossible scenarios like two people using the same object or occupying the same space. To address this, we formalise the N-Body Problem and propose a suite of metrics to evaluate both performance (speed-up, task coverage) and feasibility (spatial collisions, object conflicts and causal constraints). We then introduce a structured prompting strategy that guides a Vision-Language Model (VLM) to reason about the 3D environment, object usage, and temporal dependencies to produce a viable parallel execution. On 100 videos from EPIC-Kitchens and HD-EPIC, our method for N = 2 boosts action coverage by 45% over a baseline prompt for Gemini 2.5 Pro, while simultaneously slashing collision rates, object and causal conflicts by 55%, 45% and 55% respectively.
format Preprint
id arxiv_https___arxiv_org_abs_2512_11393
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The N-Body Problem: Parallel Execution from Single-Person Egocentric Video
Zhu, Zhifan
Huang, Yifei
Sato, Yoichi
Damen, Dima
Computer Vision and Pattern Recognition
Humans can intuitively parallelise complex activities, but can a model learn this from observing a single person? Given one egocentric video, we introduce the N-Body Problem: how N individuals, can hypothetically perform the same set of tasks observed in this video. The goal is to maximise speed-up, but naive assignment of video segments to individuals often violates real-world constraints, leading to physically impossible scenarios like two people using the same object or occupying the same space. To address this, we formalise the N-Body Problem and propose a suite of metrics to evaluate both performance (speed-up, task coverage) and feasibility (spatial collisions, object conflicts and causal constraints). We then introduce a structured prompting strategy that guides a Vision-Language Model (VLM) to reason about the 3D environment, object usage, and temporal dependencies to produce a viable parallel execution. On 100 videos from EPIC-Kitchens and HD-EPIC, our method for N = 2 boosts action coverage by 45% over a baseline prompt for Gemini 2.5 Pro, while simultaneously slashing collision rates, object and causal conflicts by 55%, 45% and 55% respectively.
title The N-Body Problem: Parallel Execution from Single-Person Egocentric Video
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2512.11393