Transformer fusion for indoor RGB-D semantic segmentation

Fusing geometric cues with visual appearance is an imperative theme for RGB-D indoor semantic segmentation. Existing methods commonly adopt convolutional modules to aggregate multi-modal features, paying little attention to explicitly leveraging the long-range dependencies in feature fusion. Therefore, it is challenging for existing methods to accurately segment objects with large-scale variations. In this paper, we propose a novel transformer-based fusion scheme, named TransD-Fusion, to better model contextualized awareness. Specifically, TransD-Fusion consists of a self-refinement module, a calibration scheme with cross-interaction, and a depth-guided fusion. The objective is to first improve modality-specific features with self- and cross-attention, and then explore the geometric cues to better segment objects sharing a similar visual appearance. Additionally, our transformer fusion benefits from a semantic-aware position encoding which spatially constrains the attention to neighboring pixels. Extensive experiments on RGB-D benchmarks demonstrate that the proposed method performs well over the state-of-the-art methods by large margins.