From Scenes to Elements: Multi-Granularity Evidence Retrieval for Verifiable Multimodal RAG

Fuente: arXiv
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Autores principales: Chen, Guanhua, Huang, Chuyue, Yao, Yutong, Liu, Shudong, Song, Xueqing, Chao, Lidia S., Wong, Derek F.
Formato: Preprint
Publicado: 2026
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author Chen, Guanhua
Huang, Chuyue
Yao, Yutong
Liu, Shudong
Song, Xueqing
Chao, Lidia S.
Wong, Derek F.
author_facet Chen, Guanhua
Huang, Chuyue
Yao, Yutong
Liu, Shudong
Song, Xueqing
Chao, Lidia S.
Wong, Derek F.
contents Multimodal Retrieval-Augmented Generation (RAG) systems retrieve evidence at coarse granularities (entire images or scenes), creating a mismatch with fine-grained user queries and making failures unverifiable. We introduce GranuVistaVQA, a multimodal benchmark featuring real-world landmarks with element-level annotations across multiple viewpoints, capturing the partial observation challenge where individual images contain only subsets of entities. We further propose GranuRAG, a multi-granularity framework that treats visual elements as first-class retrieval units through three stages: element-level detection and classification, multi-granularity cross-modal alignment for evidence retrieval, and attribution-constrained generation. By grounding retrieval at the element level rather than relying on implicit attention, our approach enables transparent error diagnosis. Experiments demonstrate that GranuRAG achieves up to 29.2% improvement over six strong baselines for this task.
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id arxiv_https___arxiv_org_abs_2605_15019
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle From Scenes to Elements: Multi-Granularity Evidence Retrieval for Verifiable Multimodal RAG
Chen, Guanhua
Huang, Chuyue
Yao, Yutong
Liu, Shudong
Song, Xueqing
Chao, Lidia S.
Wong, Derek F.
Computation and Language
Multimodal Retrieval-Augmented Generation (RAG) systems retrieve evidence at coarse granularities (entire images or scenes), creating a mismatch with fine-grained user queries and making failures unverifiable. We introduce GranuVistaVQA, a multimodal benchmark featuring real-world landmarks with element-level annotations across multiple viewpoints, capturing the partial observation challenge where individual images contain only subsets of entities. We further propose GranuRAG, a multi-granularity framework that treats visual elements as first-class retrieval units through three stages: element-level detection and classification, multi-granularity cross-modal alignment for evidence retrieval, and attribution-constrained generation. By grounding retrieval at the element level rather than relying on implicit attention, our approach enables transparent error diagnosis. Experiments demonstrate that GranuRAG achieves up to 29.2% improvement over six strong baselines for this task.
title From Scenes to Elements: Multi-Granularity Evidence Retrieval for Verifiable Multimodal RAG
topic Computation and Language
url https://arxiv.org/abs/2605.15019