CCF: Complementary Collaborative Fusion for Domain Generalized Multi-Modal 3D Object Detection

Fuente: arXiv
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Main Authors: Wu, Yuchen, Wang, Kun, Pan, Yining, Zhao, Na
Format: Preprint
Published: 2026
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author Wu, Yuchen
Wang, Kun
Pan, Yining
Zhao, Na
author_facet Wu, Yuchen
Wang, Kun
Pan, Yining
Zhao, Na
contents Multi-modal fusion has emerged as a promising paradigm for accurate 3D object detection. However, performance degrades substantially when deployed in target domains different from training. In this work, focusing on dual-branch proposal-level detectors, we identify two factors that limit robust cross-domain generalization: 1) in challenging domains such as rain or nighttime, one modality may undergo severe degradation; 2) the LiDAR branch often dominates the detection process, leading to systematic underutilization of visual cues and vulnerability when point clouds are compromised. To address these challenges, we propose three components. First, Query-Decoupled Loss provides independent supervision for 2D-only, 3D-only, and fused queries, rebalancing gradient flow across modalities. Second, LiDAR-Guided Depth Prior augments 2D queries with instance-aware geometric priors through probabilistic fusion of image-predicted and LiDAR-derived depth distributions, improving their spatial initialization. Third, Complementary Cross-Modal Masking applies complementary spatial masks to the image and point cloud, encouraging queries from both modalities to compete within the fused decoder and thereby promoting adaptive fusion. Extensive experiments demonstrate substantial gains over state-of-the-art baselines while preserving source-domain performance. Code and models are publicly available at https://github.com/IMPL-Lab/CCF.
format Preprint
id arxiv_https___arxiv_org_abs_2603_23276
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle CCF: Complementary Collaborative Fusion for Domain Generalized Multi-Modal 3D Object Detection
Wu, Yuchen
Wang, Kun
Pan, Yining
Zhao, Na
Computer Vision and Pattern Recognition
Multi-modal fusion has emerged as a promising paradigm for accurate 3D object detection. However, performance degrades substantially when deployed in target domains different from training. In this work, focusing on dual-branch proposal-level detectors, we identify two factors that limit robust cross-domain generalization: 1) in challenging domains such as rain or nighttime, one modality may undergo severe degradation; 2) the LiDAR branch often dominates the detection process, leading to systematic underutilization of visual cues and vulnerability when point clouds are compromised. To address these challenges, we propose three components. First, Query-Decoupled Loss provides independent supervision for 2D-only, 3D-only, and fused queries, rebalancing gradient flow across modalities. Second, LiDAR-Guided Depth Prior augments 2D queries with instance-aware geometric priors through probabilistic fusion of image-predicted and LiDAR-derived depth distributions, improving their spatial initialization. Third, Complementary Cross-Modal Masking applies complementary spatial masks to the image and point cloud, encouraging queries from both modalities to compete within the fused decoder and thereby promoting adaptive fusion. Extensive experiments demonstrate substantial gains over state-of-the-art baselines while preserving source-domain performance. Code and models are publicly available at https://github.com/IMPL-Lab/CCF.
title CCF: Complementary Collaborative Fusion for Domain Generalized Multi-Modal 3D Object Detection
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.23276