IGReg: Image-Geometry-Assisted Point Cloud Registration via Selective Correlation Fusion

Point cloud registration suffers from repeated patterns and low geometric structures in indoor scenes. The recent transformer utilises attention mechanism to capture the global correlations in feature space and improves the registration performance. However, for indoor scenarios, global correlation loses its advantages as it cannot distinguish real useful features and noise. To address this problem, we propose an image-geometry-assisted point cloud registration method by integrating image information into point features and selectively fusing the geometric consistency with respect to reliable salient areas. Firstly, an Intra-Image-Geometry fusion module is proposed to integrate the texture and structure information into the point feature space by the cross-attention mechanism. Initial corresponding superpoints are acquired as salient anchors in the source and target. Then, a selective correlation fusion module is designed to embed the correlations between the salient anchors and points. During training, the saliency location and selective correlation fusion modules exchange information iteratively to identify the most reliable salient anchors and achieve effective feature fusion. The obtained distinctive point cloud features allow for accurate correspondence matching, leading to the success of indoor point cloud registration. Extensive experiments are conducted on 3DMatch and 3DLoMatch datasets to demonstrate the outstanding performance of the proposed approach compared to the state-of-the-art, particularly in those geometrically challenging cases such as repetitive patterns and low-geometry regions.