Sigma: Siamese Mamba Network for Multi-Modal Semantic Segmentation

Zifu Wan, Pingping Zhang, Yuhao Wang, Silong Yong, Simon Stepputtis, Katia Sycara, Yaqi Xie; Proceedings of the Winter Conference on Applications of Computer Vision (WACV), 2025, pp. 1734-1744

Multi-modal semantic segmentation significantly enhances AI agents' perception and scene understanding especially under adverse conditions like low-light or overexposed environments. Leveraging additional modalities (X-modality) like thermal and depth alongside traditional RGB provides complementary information enabling more robust and reliable segmentation. In this work we introduce Sigma a Siamese Mamba network for multi-modal semantic segmentation utilizing the Selective Structured State Space Model Mamba. Unlike conventional methods that rely on CNNs with their limited local receptive fields or Vision Transformers (ViTs) which offer global receptive fields at the cost of quadratic complexity our model achieves global receptive fields coverage with linear complexity. By employing a Siamese encoder and innovating a Mamba fusion mechanism we effectively select essential information from different modalities. A decoder is then developed to enhance the channel-wise modeling ability of the model. Our method Sigma is rigorously evaluated on both RGB-Thermal and RGB-Depth segmentation tasks demonstrating its superiority and marking the first successful application of State Space Models (SSMs) in multi-modal perception tasks. Code is available at https://github.com/zifuwan/Sigma.