RIDGE: Region-Informed Derivative-Guided Evidence Selection for Long Video Understanding

Shanqing Xu, Meng Luo, Mengchen Qian, Yuhui Gao, Siyue Peng, Xiaohan Zhong, Xiaojin Zhang, Zhongyu Wei, Wei Chen, Xiang Bai


Abstract
Long videos contain far more visual content than Large Vision-Language Models (LVLMs) can process under a fixed visual-token budget, making frame selection essential. Existing query-aware selectors usually estimate frame-query relevance and build a compact subset from high-scoring frames. Although their mechanisms differ, the similarity sequence is still often treated primarily as values to rank or sample from, rather than as an ordered signal whose shape reflects how query-relevant evidence emerges, peaks, and fades over time. This can obscure frames that explain, contextualize, or follow an event, because such evidence may lie on the rising or falling sides of a nearby relevance peak and receive lower absolute scores. We propose RIDGE, a frame selection framework that reads the frame-query similarity curve as a temporal signal. By using local changes and curvature, RIDGE partitions the timeline into structural regions and applies region-specific selection to preserve event cores, transitions, buildup, aftermath, and contextual frames under a fixed budget. It is a lightweight post-processing step on precomputed frame-query scores and requires neither training nor iterative LVLM calls. Across four long-video benchmarks and three backbones, RIDGE achieves the best performance in most settings and remains competitive in the others.
Anthology ID:
2026.findings-emnlp.1813
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
38717–38734
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URL:
https://aclanthology.org/2026.findings-emnlp.1813/
DOI:
Bibkey:
Cite (ACL):
Shanqing Xu, Meng Luo, Mengchen Qian, Yuhui Gao, Siyue Peng, Xiaohan Zhong, Xiaojin Zhang, Zhongyu Wei, Wei Chen, and Xiang Bai. 2026. RIDGE: Region-Informed Derivative-Guided Evidence Selection for Long Video Understanding. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 38717–38734, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
RIDGE: Region-Informed Derivative-Guided Evidence Selection for Long Video Understanding (Xu et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1813.pdf