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Main Authors: Zhu, Fangrui, Xi, Yunfeng, Ni, Jianmo, Cai, Mu, Gong, Boqing, Zhao, Long, Qu, Chen, Miao, Ian, Li, Yi, Zhong, Cheng, Jiang, Huaizu, Patel, Shwetak
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.06561
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author Zhu, Fangrui
Xi, Yunfeng
Ni, Jianmo
Cai, Mu
Gong, Boqing
Zhao, Long
Qu, Chen
Miao, Ian
Li, Yi
Zhong, Cheng
Jiang, Huaizu
Patel, Shwetak
author_facet Zhu, Fangrui
Xi, Yunfeng
Ni, Jianmo
Cai, Mu
Gong, Boqing
Zhao, Long
Qu, Chen
Miao, Ian
Li, Yi
Zhong, Cheng
Jiang, Huaizu
Patel, Shwetak
contents Egocentric video understanding is inherently complex due to the dynamic 4D nature of the environment, where camera motion and object displacements necessitate a continuous re-evaluation of spatial relations. In this work, we target a suite of under-explored egocentric 4D reasoning tasks, including fixture interaction counting, viewpoint-relative fixture location, object movement itinerary tracking, and stationary object localization, that require fundamentally different cognitive operations: spatial anchoring, temporal tracking, and duration reasoning. We observe that these structural differences make task-agnostic approaches insufficient: generic Chain-of-Thought methods lack task-appropriate reasoning primitives, and uniform reinforcement learning actively destabilizes performance on spatial tasks. To address this, we propose EgoReasoner, a two-stage framework that aligns both the reasoning scaffold and the reward signal to each task's cognitive structure. In the first stage, Task-Adaptive Thinking Templates guide the synthesis of structured CoT traces that teach the model to reason adaptively across task types via supervised fine-tuning. In the second stage, task-aware reward functions verify entity grounding, temporal alignment, and task-adaptive logical consistency, selectively strengthening each reasoning pathway via reinforcement fine-tuning with GRPO. Our 3B-parameter model, trained on only 16K samples, achieves 37.5% average accuracy on the challenging HD-EPIC benchmark, surpassing Qwen2.5-VL-7B (25.7%) by over 10 points.
format Preprint
id arxiv_https___arxiv_org_abs_2603_06561
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle EgoReasoner: Learning Egocentric 4D Reasoning via Task-Adaptive Structured Thinking
Zhu, Fangrui
Xi, Yunfeng
Ni, Jianmo
Cai, Mu
Gong, Boqing
Zhao, Long
Qu, Chen
Miao, Ian
Li, Yi
Zhong, Cheng
Jiang, Huaizu
Patel, Shwetak
Computer Vision and Pattern Recognition
Egocentric video understanding is inherently complex due to the dynamic 4D nature of the environment, where camera motion and object displacements necessitate a continuous re-evaluation of spatial relations. In this work, we target a suite of under-explored egocentric 4D reasoning tasks, including fixture interaction counting, viewpoint-relative fixture location, object movement itinerary tracking, and stationary object localization, that require fundamentally different cognitive operations: spatial anchoring, temporal tracking, and duration reasoning. We observe that these structural differences make task-agnostic approaches insufficient: generic Chain-of-Thought methods lack task-appropriate reasoning primitives, and uniform reinforcement learning actively destabilizes performance on spatial tasks. To address this, we propose EgoReasoner, a two-stage framework that aligns both the reasoning scaffold and the reward signal to each task's cognitive structure. In the first stage, Task-Adaptive Thinking Templates guide the synthesis of structured CoT traces that teach the model to reason adaptively across task types via supervised fine-tuning. In the second stage, task-aware reward functions verify entity grounding, temporal alignment, and task-adaptive logical consistency, selectively strengthening each reasoning pathway via reinforcement fine-tuning with GRPO. Our 3B-parameter model, trained on only 16K samples, achieves 37.5% average accuracy on the challenging HD-EPIC benchmark, surpassing Qwen2.5-VL-7B (25.7%) by over 10 points.
title EgoReasoner: Learning Egocentric 4D Reasoning via Task-Adaptive Structured Thinking
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.06561