Second-order Robust Iterative Pose Optimization for Fine-grained Cross-View Localization

Fine-grained cross-view localization seeks to estimate precise camera poses by matching ground images with GPS-tagged aerial imagery. Existing methods typically employ first-order iterative optimization to progressively update the camera pose based on cross-view feature correspondences. However, they rely on local features and neglect global and complementary contextual information, making them prone to local optima and slow convergence under large initial errors or strong disturbances. To overcome these limitations, we propose a second-order robust iterative pose estimation framework for fine-grained cross-view localization. Firstly, we devise a second-order deep iterative optimization module to capture complementary forward and backward motion cues, leading to a bidirectional correlation volume. A motion aggregator uses the volume to approximate the dynamics of second-order iterators, substantially facilitating convergence and robustness. In addition, a bidirectional motion-aware robust regularization module mitigates geometric distortions and outlier interference by leveraging bidirectional motion cues to generate fine-grained confidence maps, adaptively suppressing unreliable regions and enhancing the stability of iterative optimization and pose estimation accuracy. Extensive experiments demonstrate that the proposed framework achieves faster convergence and higher pose estimation accuracy than state-of-the-art methods, particularly under large initial errors and challenging conditions.