This manuscript presents a new CNN-based visual localization method that seeks a camera location of an input RGB image with respect to a pre-collected RGB-D images database. To determine an accurate camera pose, we employ a coarse-to-fine localization manner that firstly finds coarse location candidates via image retrieval, then refines them using local 3D structure represented by each retrieved RGB-D image. We use a CNN feature extractor and a relative pose estimator for coarse prediction that do not sufficiently require a scene-specific training. Furthermore, we propose a new pose refinement-verification module that simultaneously evaluates and refines camera poses using differentiable renderer. Experimental results on public datasets show that our proposed pipeline achieves accurate localization on both trained and unknown scenes.
Chanchang Tsai, Hajime Taira, Masatoshi Okutomi, "Learned visual localization with camera pose refinement and verification based on differentiable renderer" in Electronic Imaging, 2023, pp 102-1 - 102-6, https://doi.org/10.2352/EI.2023.35.17.3DIA-102