The commonly adopted detect-then-match approach to registration finds difficulties in the cross-modality cases due to the incompatible keypoint detection and inconsistent feature description. We propose, 2D3D-MATR, a detection-free method for accurate and robust registration between images and point clouds. Our method adopts a coarse-to-fine pipeline where it first computes coarse correspondences between downsampled patches of the input image and the point cloud and then extends them to form dense correspondences between pixels and points within the patch region. The coarse-level patch matching is based on transformer which jointly learns global contextual constraints with self-attention and cross-modality correlations with cross-attention. To resolve the scale ambiguity in patch matching, we construct a multi-scale pyramid for each image patch and learn to find for each point patch the best matching image patch at a proper resolution level. Extensive experiments on two public benchmarks demonstrate that 2D3D-MATR outperforms the previous state-of-the-art P2-Net by around $20$ percentage points on inlier ratio and over $10$ points on registration recall. Our code and models are available at \url{https://github.com/minhaolee/2D3DMATR}.

采用2D3D-MATR方法，我们提出了一种无需检测的方法，用于图像和点云之间的准确且鲁棒的配准。该方法在粗匹配的基础上，通过学习全局上下文约束和跨模态相关性，通过transformer实现多尺度金字塔和图像块焦点学习，解决了尺度不确定性问题，从而获得了比之前的最优模型P2-Net更高的配准率和稳定度。

2D3D-MATR: 图像与点云之间基于2D-3D匹配变换器的无检测配准