MMGraphRAG: Bridging Vision and Language with Interpretable Multimodal Knowledge Graphs

Abstract

Large Language Models (LLMs) often suffer from hallucinations, which Retrieval-Augmented Generation (RAG) and GraphRAG mitigate by incorporating external knowledge and knowledge graphs (KGs). However, GraphRAG remains text-centric due to the difficulty of constructing fine-grained Multimodal KGs (MMKGs). Existing fusion methods, such as shared embeddings or captioning, require task-specific training and fail to preserve visual structural knowledge or cross-modal reasoning paths. To bridge this gap, we propose MMGraphRAG, which integrates visual scene graphs with text KGs via a novel cross-modal fusion approach. It introduces SpecLink, a method leveraging spectral clustering for accurate cross-modal entity linking and path-based retrieval to guide generation. We also release the CMEL dataset, specifically designed for fine-grained multi-entity alignment in complex multimodal scenarios. Evaluations on CMEL, DocBench, and MMLongBench demonstrate that MMGraphRAG achieves state-of-the-art performance, showing robust domain adaptability and superior multimodal information processing capabilities.