ArrowGEV: Grounding Events in Video via Learning the Arrow of Time

Fuente: arXiv
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Auteurs principaux: Yu, Fangxu, Lu, Ziyao, Niu, Liqiang, Meng, Fandong, Zhou, Jie
Format: Preprint
Publié: 2026
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author Yu, Fangxu
Lu, Ziyao
Niu, Liqiang
Meng, Fandong
Zhou, Jie
author_facet Yu, Fangxu
Lu, Ziyao
Niu, Liqiang
Meng, Fandong
Zhou, Jie
contents Grounding events in videos serves as a fundamental capability in video analysis. While Vision Language Models (VLMs) are increasingly employed for this task, existing approaches predominantly train models to associate events with timestamps in the forward video only. This paradigm hinders VLMs from capturing the inherent temporal structure and directionality of events, thereby limiting robustness and generalization. To address this limitation, inspired by the arrow of time in physics, which characterizes the intrinsic directionality of temporal processes, we propose ArrowGEV, a reinforcement learning framework that explicitly models temporal directionality in events to improve both event grounding and temporal directionality understanding in VLMs. Specifically, we categorize events into time-sensitive (e.g., putting down a bag) and time-insensitive (e.g., holding a towel in the left hand). The former denote events whose reversal substantially alters their meaning, while the latter remain semantically unchanged under reversal. For time-sensitive events, ArrowGEV introduces a reward that encourages VLMs to discriminate between forward and backward videos, whereas for time-insensitive events, it enforces consistent grounding across both directions. Extensive experiments demonstrate that ArrowGEV not only improves grounding precision and temporal directionality recognition, but also enhances general video understanding and reasoning ability.
format Preprint
id arxiv_https___arxiv_org_abs_2601_06559
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ArrowGEV: Grounding Events in Video via Learning the Arrow of Time
Yu, Fangxu
Lu, Ziyao
Niu, Liqiang
Meng, Fandong
Zhou, Jie
Computer Vision and Pattern Recognition
Grounding events in videos serves as a fundamental capability in video analysis. While Vision Language Models (VLMs) are increasingly employed for this task, existing approaches predominantly train models to associate events with timestamps in the forward video only. This paradigm hinders VLMs from capturing the inherent temporal structure and directionality of events, thereby limiting robustness and generalization. To address this limitation, inspired by the arrow of time in physics, which characterizes the intrinsic directionality of temporal processes, we propose ArrowGEV, a reinforcement learning framework that explicitly models temporal directionality in events to improve both event grounding and temporal directionality understanding in VLMs. Specifically, we categorize events into time-sensitive (e.g., putting down a bag) and time-insensitive (e.g., holding a towel in the left hand). The former denote events whose reversal substantially alters their meaning, while the latter remain semantically unchanged under reversal. For time-sensitive events, ArrowGEV introduces a reward that encourages VLMs to discriminate between forward and backward videos, whereas for time-insensitive events, it enforces consistent grounding across both directions. Extensive experiments demonstrate that ArrowGEV not only improves grounding precision and temporal directionality recognition, but also enhances general video understanding and reasoning ability.
title ArrowGEV: Grounding Events in Video via Learning the Arrow of Time
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2601.06559